Common Problems in Neurology

Common Problems in Neurology

Questions

1. A 65-year-old man presents to the emergency room with 2 hours of vertigo. He has a history of hypertension and hypercholesterolemia. His examination shows spontaneous left beating nystagmus while sitting at rest, and he is unsteady on standing. Head impulse testing is normal with no corrective saccade. What is the most likely diagnosis?

A. BPPV

B. Ménière

C. Migraine

D. Stroke

E. Vestibular neuritis

1. Answer D. (MN-5) Stroke. The patient has vascular risk factors, and head impulse testing is normal. In BPPV, nystagmus is brought on by positioning (Dix-Hallpike maneuver, Figure 2.1.1) and not spontaneous, and head impulse testing should demonstrate a unilateral delayed corrective saccade. Head impulse testing is abnormal in those with vestibular neuritis. A migraine is not likely given there is no history reported of headache and spontaneous nystagmus would not be seen. A diagnosis of Ménière syndrome would be entertained in those with repeated attacks of vertigo associated with hearing loss and tinnitus.

For further review, Ménière syndrome and BPPV are covered in Merritt’s Neurology 14th edition, Chapter 62.

FIGURE 2.1.1 (Reprinted with permission from Fife TD, Iverson DJ, Lempert T, et al. Practice parameter: therapies for benign paroxysmal positional vertigo (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2008;70(22):2067-2074.)

2. A 35-year-old woman describes vertigo occurring after moving her head in a certain way such as getting out of bed. It lasts 20 to 30 seconds and is improved if she stays still. She has no other medical problems. On examination, cranial nerves, strength, sensation, coordination, and gait all test normal. What is the next best step?

A. Brain MRI

B. Comprehensive audiologic examination

C. Performance of the Dix-Hallpike maneuver

D. Referral to otorhinolaryngology

E. Video nystagmography

2. Answer C. (MN-5) Performance of the Dix-Hallpike maneuver. Vertigo brought on by characteristic head movements and improved when still is strongly suggestive of BPPV. The most common form, posterior canal BPPV, is often precipitated by rolling and getting in or out of bed. It can be diagnosed by the Dix-Hallpike maneuver, which if positive will recapitulate the vertigo syndrome with evident and characteristic upbeat and torsional nystagmus on examination. This test is easily done and diagnostic without the need for MRI, CAE, VNG, or referral. If positive, the condition can then be treated by repositioning exercises such as the Epley maneuver, the first step of which is the Dix-Hallpike maneuver.

The Dix-Hallpike maneuver is demonstrated in Figure 4.15, and the Epley maneuver is demonstrated in Figure 62.1.

BPPV is covered in Chapter 62.

3. A 55-year-old man complains of a sound in his left ear. He describes it as pulsatile. On examination, a pulsatile bruit can be heard when listening around the left ear. What test is likely to be most helpful?

A. Comprehensive audiologic examination

B. CT angiography of the head and neck

C. CT of the temporal bones

D. Dix-Hallpike maneuver

E. Video nystagmography

3. Answer B. (MN-5) CT angiography of the head and neck. The presence of pulsatile tinnitus raises the question of a vascular anomaly such as an arteriovenous malformation or fistula or carotid stenosis with turbulent flow. A comprehensive audiologic examination is important in the diagnosis of nonpulsatile tinnitus as hearing loss is a common association. VNG and the Dix-Hallpike maneuver are helpful in the diagnosis of vertigo. And CT of the temporal bones is useful in trauma and in looking for superior canal dehiscence, which can present with pulsatile tinnitus among other symptoms but would not have a bruit on examination.

Computed tomography including angiography is covered in Chapter 25. Cerebral vascular malformations are reviewed in Chapter 42.

4. A healthy 14-year-old young woman presents to the emergency room after an event in a high school classroom witnessed by her teacher. She is lying comfortably on a gurney. Her EKG demonstrates a normal sinus rhythm with normal intervals. She states that someone in her classroom had accidentally cut their arm and at the sight of it she developed lightheadedness, blackening of her vision, and loss of consciousness. What is the most appropriate next step?

A. Ask the patient and witnesses about her postevent recovery

B. Check orthostatic blood pressure

C. Order an echocardiogram

D. Order an EEG

E. Order CBC

4. Answer A. (MN-6) The most likely diagnosis is vasovagal syncope. The event appeared to be triggered by the sight of blood, a common trigger, and was associated with presyncopal symptoms. Other precipitating factors in adolescents may include a hot environment, hyperventilation, and standing quickly from a seated or squatting position. It is important to confirm that after the event she regained awareness quickly and did not experience prolonged confusion or amnesia, which would be inconsistent with vasovagal syncope. Further testing is unlikely to clarify the diagnosis.

Syncope is covered in Chapter 6.

5. An 82-year-old woman presents to the clinic after an episode of falling in the bathroom at night. She describes lightheadedness after rising from the toilet followed by finding herself on the floor of the bathroom. She has a past medical history of hypertension and insomnia and was recently started on amitriptyline at bedtime. What is the most likely diagnosis?

A. Cardiogenic syncope

B. Focal seizure

C. Generalized tonic-clinic seizure

D. Micturition syncope

E. Vasovagal syncope

5. Answer D. (MN-6) Micturition syncope, a type of situational syncope, which itself is considered a form of vasovagal syncope. Her symptoms are strongly associated with micturition and changes in posture and are likely exacerbated by the anticholinergic properties of amitriptyline. Vasovagal syncope is a broad diagnostic category describing syncope due to inappropriate neural modulation of heart rate and blood pressure and is less specific to this scenario. The circumstances and prodrome of lightheadedness are less suggestive of seizures.

Syncope is covered in Chapter 6; seizures and epilepsy are covered in Chapter 7 and in Section IX (Epilepsy and Paroxysmal Disorders).

6. A 68-year-old man presents to the clinic with two recent episodes of sudden falls at home resulting in minor facial injuries. Both times, he found himself on the floor amnestic to what had occurred. There were no witnesses. His past medical history is significant for a history of a myocardial infarction and congestive heart disease. He takes metoprolol and lisinopril. An EKG performed in your office shows left bundle branch block. His vital signs are the following: When standing, BP was 155/90, HR 85 and lying down BP was 165/92, HR 82. What is the most appropriate next step?

A. Admit the patient for video/EEG monitoring

B. Order outpatient ambulatory cardiac telemetry

C. Referral to cardiology

D. Start an anticonvulsant

E. Stop lisinopril

6. Answer C. (MN-6) This history of sudden loss of consciousness without prodromal symptoms in an older patient with a significant cardiac history is highly concerning for a diagnosis of cardiogenic syncope, which is associated with a high risk of morbidity and mortality. While ordering a wearable electrocardiographic telemetry is appropriate, cardiac arrhythmia is only one possible mechanism and a thorough cardiac evaluation should be undertaken by the appropriate subspecialty provider.

An evaluation and differential for syncope is covered in Chapter 6.

7. A 52-year-old woman with no past medical history is referred by her primary care provider for episodes of loss of consciousness. She describes sudden anxiety, palpitations, and tachycardia, followed by confusion and amnesia that lasts many minutes. Her sister, who came with her to the visit, has witnessed several events and said that all of the events have been similar and that the patient stares, is unresponsive while seated, and appears to be panting. What is the most likely diagnosis?

A. Cardiogenic syncope

B. Focal seizures

C. Generalized anxiety disorder

D. Panic attacks

E. Psychogenic nonepileptic seizures

7. Answer B. (MN-6) The stereotyped nature of the events, the unresponsiveness with eyes open, and the prolonged confusion are hallmarks of seizures. Focal seizures can have a broad variety of symptoms that can mimic behavioral or psychiatric conditions and require a high index of suspicion. Panic attacks and generalized anxiety disorders do not cause altered awareness. These events are not consistent with syncope because there is no loss of postural tone with the impaired awareness. Psychogenic nonepileptic seizures are also less likely because the events are stereotyped.

Seizures and epilepsy are covered in Chapter 7 and in Section IX (Epilepsy and Paroxysmal Disorders). Anxiety disorders are covered in Chapter 155. The treatment of psychogenic nonepileptic seizures is covered in Chapter 61.

8. A 19-year-old man is referred because of a concern for seizure. He describes getting up in the morning and suddenly feeling dizzy and passing out. His mother heard a thump from another room and found him shaking for several seconds. He quickly regained awareness and told his mother that he was fine. What is the most likely diagnosis?

A. Clonic seizures

B. Convulsive syncope

C. Generalized tonic-clinic seizures

D. Psychogenic nonepileptic seizures

E. Tonic seizures

8. Answer B. (MN-6) The prodrome and rapid return to baseline are more consistent with convulsive syncope. Convulsive movements may be seen in many forms of syncope, including vasovagal etiology. The shaking associated with generalized tonic-clonic and clonic seizures is typically longer (30-60 seconds). Tonic seizures do not typically occur in individuals with normal intellect.

Clinical features of other spells potentially mistaken for syncope are covered in Chapter 6.

9. A 35-year-old man presents with a generalized seizure lasting 1 minute in the context of drug-induced hyponatremia of 119. What is the next best step in management?

A. Correct hyponatremia and do not start an antiepileptic

B. Obtain brain MRI

C. Obtain electroencephalogram

D. Start a long-term antiepileptic

E. Start an antiepileptic until sodium level has normalized

9. Answer A. (MN-7) Provoked seizures due to metabolic disturbance are not thought to portend an increased risk of short-term or long-term seizure once the metabolic disturbance is corrected, assuming it did not cause any permanent cerebral damage. It is therefore not necessary to start an antiepileptic drug or proceed with further diagnostic workup.

Seizures are covered in Chapter 7. The management of epilepsy is covered in Chapter 61.

10. A 23-year-old woman presents to the ER with the first seizure of her life and then returns to baseline. The seizure appears to be unprovoked. What is the next step in management?

A. No additional management steps are required unless seizure recurs

B. Obtain an EEG

C. Obtain both brain imaging and an EEG

D. Obtain brain imaging

E. Start an antiepileptic medication

10. Answer C. (MN-7) The likelihood of recurrent seizure after a first unprovoked seizure is about 20% to 40%. The general practice is to not start an antiepileptic immediately after a first lifetime seizure but rather to obtain both an EEG and brain imaging. If the EEG shows epileptiform discharges or the MRI shows an abnormality that can presumably be the focus of a seizure, then the likelihood of a recurrent seizure increases to 50% to 70%, facilitating the diagnosis of epilepsy. Antiepileptic treatment is initiated after the diagnosis of epilepsy.

The initial diagnostic evaluation of epilepsy is covered in Chapter 61. Seizures are covered in Chapter 7.

11. A 26-year-old woman with a history of depression, childhood abuse, traumatic brain injury, and posttraumatic stress disorder presents after a cluster of episodic whole-body shaking. When you evaluate her in the emergency room, she is back to baseline. Her partner recorded one of the episodes on his phone and shows it to you for your review. Which features would be most consistent with a psychogenic nonepileptic episode as opposed to an epileptic seizure?

A. Forced eye closure

B. Gaze deviation

C. Head turning

D. Slow return to cognitive baseline after the episode

E. Synchronous limb movements

11. Answer A. (MN-7) Core features of nonepileptic episodes include horizontal head movements, asynchronous limb movements, eye opening, and waxing and waning of the abnormal movements during a given episode. Epileptic seizures tend to have a period of diminished function after the seizure (eg, confusion, weakness, numbness).

Clinical features and treatment of psychogenic nonepileptic seizures are covered in Chapter 61.

12. A 50-year-old woman with a history of epilepsy has a convulsive seizure at home. When EMS arrives at the patient’s home 15 minutes later, she is still seizing. EMS decides to administer a medication to abort the seizure. The patient weighs approximately 70 kg. Which of these options is an appropriate choice?

A. Intramuscular midazolam 10 mg

B. Intravenous levetiracetam 60 mg/kg

C. Intravenous lorazepam 2 mg

D. Intravenous phenobarbital 20 mg/kg

E. Intravenous phenytoin 20 mg/kg

12. Answer A. (MN-7) Benzodiazepines are the first-line agent for aborting a prolonged seizure. Traditionally, IV lorazepam was used at a dose of 0.1 mg/kg in two divided doses; however, the RAMPART study showed that IM midazolam at a dose of 10 mg is equally as effective, as it can be administered quickly without needing to obtain IV access. For this reason, choice A is correct. Choice C is incorrect because the dose is higher than recommended (Table 2.12.1). Phenytoin, phenobarbital, and levetiracetam are second-line therapies for status epilepticus and are given after the benzodiazepines.

The diagnosis and treatment of status epilepticus is covered in Chapter 7 (Figure 7.2) with medication titration approaches explored further in Chapter 34.

TABLE 2.12.1 Emergent First-Line Therapy Benzodiazepine Agents and Dosing

Benzodiazepine	Route	Dosing
Lorazepam	IV	0.1 mg/kg IV (max 4 mg/dose) and can repeat at 5-10 min
Diazepam	IV	0.15 mg/kg IV (max 10 mg/dose) and can repeat in 5 min
	PR	0.2 mg/kg PR for >12 y
		0.3 mg/kg PR for 6-11 y
		0.5 mg/kg PR for 2-5 y
Midazolam	IM	0.2 mg/kg IM (max 10 mg)
	Intranasal	0.2 mg/kg intranasal
	Buccal	0.5 mg/kg buccal
IM, intramuscular; IV, intravenous; max, maximum; PR, per rectum.
Adapted by permission from Springer: Brophy GM, Bell R, Claassen J, et al; for Neurocritical Care Society Status Epilepticus Guideline Writing Committee. Guidelines for the evaluation and management of status epilepticus. Neurocrit Care. 2012;17(1):3-23. Copyright © 2012 Springer Science Business Media, LLC.

13. A 41-year-old man presented to the hospital with refractory status epilepticus. He has been receiving continuous anesthetic intravenous (IV) medications to control the seizures. He develops circulatory collapse, lactic acidosis, hypertriglyceridemia, and rhabdomyolysis. Which IV anesthetic agent is likely responsible for this constellation of symptoms?

A. Dexmedetomidine

B. Midazolam

C. Pentobarbital

D. Phenytoin

E. Propofol

13. Answer E. (MN-7) Propofol infusion syndrome is characterized by circulatory collapse, lactic acidosis, hypertriglyceridemia, and rhabdomyolysis (Table 2.13.1). The side effects associated with pentobarbital are respiratory/cardiac depression, ileus, and hypotension. The side effects associated with IV midazolam are hypotension, respiratory depression, and tachyphylaxis. The side effects associated with dexmedetomidine are bradycardia, hypotension, and dry mouth. Phenytoin is not administered by continuous IV infusion.

The diagnosis and treatment of status epilepticus is covered in Chapter 7, with medication titration approaches explored further in Chapter 34.

TABLE 2.13.1 Continuous Intravenous Anesthetic Agents for Refractory Status Epilepticus

Drug	Bolus Dose	Maintenance Dose	Side Effects
Midazolam	0.2 mg/kg (rate of 2 mg/min)	0.05-2.9 mg/kg/h	Respiratory depression
Propofol	1-2 mg/kg over 3-5 min Repeat bolus every 3-5 min until seizures stop (maximum 10 mg/kg)	30-100 µg/kg/min	Hypotension Propofol infusion syndrome (particularly at >80 µg/kg/min for >48 h)
Ketamine	1.5-4.5 mg/kg IV	2.75-5 mg/kg/h	Hypertension and tachycardia
Pentobarbital	5-15 mg/kg (up to 50 mg/min)	1-10 mg/kg/h	Hypotension Ileus
IV, intravenous.
Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

14. A 45-year-old man presents to the emergency department with 4 days of numbness in his feet, which has now began to involve his calves. On examination, reflexes are absent throughout. What is the next appropriate step?

A. Call a neurosurgery consultation for a nerve biopsy

B. Discharge home with instructions for an outpatient EMG/NCS

C. Empirically start IV steroid treatment

D. Obtain an urgent MRI of the brain

E. Perform a lumbar puncture

14. Answer E. (MN-8) Ascending numbness occurring over the course of days with associated hyporeflexia suggests this could be Guillain-Barré syndrome (GBS). The next appropriate step in diagnosis is to perform a lumbar puncture to look for cytoalbuminologic dissociation in cerebrospinal fluid analyses. Given that this localizes to the peripheral nervous system, an MRI of the brain is not indicated. As GBS can rapidly progress to involve respiratory muscles and dysautonomia, admission and monitoring in a stepdown unit or ICU is appropriate and the patient should not be discharged home. A nerve biopsy is not necessary to make the diagnosis of GBS. Plasmapheresis or IVIG (and not steroids) are considered first-line treatment for GBS, as steroids may worsen outcomes.

The diagnostic approach to peripheral neuropathic syndromes including Guillain-Barré syndrome (GBS) is covered in Chapter 8. Lumbar puncture and cerebrospinal fluid analysis are covered in Chapter 32. GBS is covered further in Chapter 91.

15. A 22-year-old woman presents to your office with complaints of diffuse burning and paresthesias throughout her extremities, which have been constant for 2 years and associated with intermittent palpitations. Her neurological examination is normal. What is the next appropriate step?

A. Obtain an MRI of the cervical spine

B. Order serum studies including TSH, B₁₂, ANA, Lyme Ab, SPEP and HbA1c

C. Refer for an urgent EMG/NCS

D. Refer to psychiatry for an evaluation of an underlying mood disorder

E. Start IVIG infusions

15. Answer B. (MN-8) This patient has clinical signs and symptoms suggestive of a small fiber neuropathy with autonomic involvement (See Table 2.15.1); therefore, initial steps in management would include screening for any possible underlying condition that would be causal. Given that this is a peripheral process, MRI of the cervical spine is not indicated (and furthermore, the symptoms involve her face as well so do not localize to the cervical spine). An EMG/NCS can be helpful to exclude large fiber involvement but is not urgent. IVIG is not indicated for treatment of small fiber neuropathy. Referral for a psychiatrist not appropriate, as one should never attribute symptoms to a psychiatric diagnosis until a complete medical workup is performed.

Acquired peripheral neuropathies are covered further in Chapter 91.

TABLE 2.15.1 Patterns of Sensory Loss

Localization	Sensory Pattern	Associated Findings
Cortical	Contralateral sensory loss	Cortical sensory loss (ie, neglect, astereognosis, agraphesthesia) Visuospatial deficits
Brain stem	Contralateral sensory loss of arm and leg with ipsilateral loss in face	Cranial neuropathies (ie, ophthalmoparesis, facial weakness) Ataxia Contralateral weakness Hyperreflexia
Spinal cord	Complete transverse lesion: loss of all sensory modalities below the level of the lesion Central cord lesion (ie, syrinx): loss of pain and temperature at and/or below the level of the lesion Anterior cord lesion: contralateral loss of pain and temperature sensation below the level of the lesion Cord hemisection (Brown-Séquard syndrome): ipsilateral loss of vibration and joint position below the level of the lesion and contralateral loss of pain and temperature two or three segments below the level of the lesion Cauda equina syndrome or conus medullaris syndrome: saddle anesthesia	Contralateral or complete paralysis below the level of the lesion Change in bladder or bowel control Areflexia/hyporeflexia at the level of the lesion with hyperreflexia below the lesion Dissociation between sensory modalities
Brachial plexus	Ipsilateral sensory loss in the distribution of more than one peripheral nerve or nerve root	Weakness in the distribution of the involved peripheral nerves or nerve roots Areflexia Neuropathic pain
Dorsal root ganglion	Complete loss of sensation of all modalities in the affected dermatome	Neuropathic pain No weakness
Nerve root	Loss or diminution of all sensory modalities in the affected dermatome	Radicular pain Weakness in the corresponding myotome Areflexia or hyporeflexia
Peripheral nerve (also see Figure 8.1)	Mononeuropathy: loss or diminution of all sensory modalities in the distribution of the nerve Polyneuropathy: distal and symmetric loss of sensation (vibration and joint position in cases of large fiber neuropathy and pain and temperature in cases of small fiber neuropathy) Mononeuritis multiplex: loss of sensation in various peripheral nerves in an asymmetric fashion	Weakness involving muscles of the corresponding peripheral nerve Distal and symmetric weakness in cases of large fiber polyneuropathy Autonomic findings Neuropathic pain Areflexia or hyporeflexia
Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

16. An 80-year-old woman complains of pain and paresthesias in the shoulders and right greater than left arm several weeks after a fall. On examination, there is sensory loss over both shoulders and extending down the right arm in a C5 distribution. Which element of the history would suggest neuroanatomic localization to the spinal cord rather than the nerve root?

A. Changes in bowel and/or bladder habits

B. Exacerbation of symptoms with Spurling sign

C. Hyporeflexia

D. Presence of neck pain

E. Weakness in the proximal right arm

16. Answer A. (MN-8) This history and examination is suggestive of syringomyelia, which localizes to the spinal cord. Spinal cord involvement may also be associated with changes in bladder or bowel habits such as urinary incontinence or frequency; these symptoms would not be expected with isolated cervical nerve root injury (Table 2.15.1). Nerve root injuries are usually associated with unilateral neurologic symptoms. Hyporeflexia suggests a lesion in the peripheral nervous system, and weakness in the proximal right arm is not specific to pathology in the spinal cord as it can be seen in various lesions in the nervous system. Spurling sign is a test for cervical radiculopathy, which would localize to the peripheral nervous system. Neck pain is a nonspecific complaint without localizing value to either the central or peripheral nervous system.

Syringomyelia is covered in Chapter 115 (Acquired and Hereditary Myelopathies). Intervertebral disk disease and radiculopathy are covered in Chapter 113.

17. Which of the following is most consistent with a diagnosis of migraine?

A. Bilateral location

B. Duration 2 minutes

C. Worsened by rest or lying down

D. Burning quality of headache

E. Pulsatile quality of headache

17. Answer A. (MN-9) The POUND mnemonic is a useful tool to identify migraine: Pulsatile quality of headache, One-day duration (4-72 h), Unilateral location, Nausea or vomiting, and Disabling intensity that is typically improved with rest or lying down (Table 2.17.1). While migraine can present bilaterally, this is often a feature associated with tension headache.

The evaluation of headache and facial pain is covered in Chapter 9. Migraine and tension-type headaches are covered further in Primary and Secondary Headache Disorders (Chapter 56).

TABLE 2.17.1 POUND Mnemonic for Identifying Migraine Headache

Pulsatile quality of headache

One-day duration (4-72 h)

Unilateral location

Nausea and vomiting

Disabling intensity

Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

18. Which, if present, most warrants further testing in a patient presenting with headache?

A. Onset at age 20 years

B. Presence of nausea

C. Severe pain intensity

D. Triggered by coughing or sneezing

E. Unilateral location

18. Answer D. (MN-9) Headache that occurs with exertional maneuvers raises concern for a disorder of CSF flow, such as an obstructive space-occupying lesion or a Chiari I malformation. The other answer choices are features typical of migraine. The SNOOP mnemonic (Systemic, Neurologic symptoms/signs, Older, Onset, Pattern Change) can help identify potential “red flags,” such as headaches induced by coughing, sneezing, or Valsalva maneuvers (Table 2.18.1).

The evaluation of headache and facial pain is covered in Chapter 9. Focal intracranial mass lesions are covered in Chapter 18. Chiari malformations are covered in Chapter 115.

TABLE 2.18.1 “Red Flags” When Evaluating Headache Symptoms

Systemic	Systemic signs/symptoms: fever, night sweats, weight loss; new headache during pregnancy or postpartum; and comorbid systemic disease (eg, HIV, malignancy)
Neurologic symptoms/signs	Change in mental status; alteration of consciousness; seizure; papilledema, ataxia, focal examination findings sensation; headache induced by Valsalva maneuvers (bending, lifting, cough, sneezing)
Older	Onset after age 50 y
Onset	Abrupt, sudden, “thunderclap”
Pattern change	Change in frequency, severity, or clinical features of the attack from previous headache history; subacute worsening over days/weeks or accelerating pattern
HIV, human immunodeficiency virus.
Adapted with permission of Oxford University Press – Books (US & UK) from Silberstein SD, Lipton RB, Dodick DW, eds. Wolff’s Headache and Other Head Pain. 8th ed. Oxford University Press; 2008; permission conveyed through Copyright Clearance Center, Inc.

19. “Thunderclap headache” is a common initial presentation in which of following clinical conditions:

A. carotid artery stenosis

B. pituitary adenoma

C. reversible cerebrovascular constriction syndrome (RCVS)

D. lightning strike injury

E. subdural hematoma

19. Answer E. (MN-9) Thunderclap headache, or a severe headache of abrupt onset that reaches maximal intensity within the first 60 seconds, is a rare but concerning presentation of headache. RCVS, pituitary apoplexy, cervical artery dissection, and spontaneous subarachnoid hemorrhage are all potential causes of thunderclap headache. Subdural hematoma typically presents with an insidious onset.

Subdural hematoma and other forms of traumatic brain injury are covered further in Chapter 47.

20. In which of the following conditions should clinicians proceed with caution in performing a lumbar puncture?

A. Bacterial meningitis

B. Idiopathic intracranial hypertension

C. Posterior fossa tumor

D. Reversible cerebrovascular constriction syndrome (RCVS)

E. Subarachnoid hemorrhage

20. Answer C. (MN-9) Lumbar puncture is a useful tool for the evaluation of cerebrospinal fluid pressure and content. CSF pressures above 25 cm H₂O, in the setting of normal fluid analysis, is suggestive of idiopathic intracranial hypertension in the right clinical setting. Lumbar puncture is also indicated in imaging-negative presentations concerning for subarachnoid hemorrhage and should be pursued. Similarly, in patients presenting with RCVS, lumbar puncture can help rule out other causes such as subarachnoid hemorrhage and primary angiitis of the central nervous system. Bacterial meningitis is life-threating if not treated emergently. CSF analysis, which includes testing for pleocytosis and microbial cultures, is necessary for diagnosis and treatment guidance. However, in cases of posterior fossa tumors, particularly large tumors, caution should be taken as a lumbar puncture may create a pressure gradient, thereby forcing contents into the foramen magnum, resulting in herniation. Diagnosis typically does not require CSF analysis, but rather tissue biopsy or resection.

Focal intracranial mass lesions are covered in Chapter 18. Lumbar puncture is covered in Chapter 32. Reversible cerebrovascular constriction syndrome (RCVS) is covered further primarily in Chapter 44 as well as in Chapters 9 and 43.

21. Which of the following is most likely to be associated with cranial neuralgia?

A. Absence of a trigger

B. Mild pain intensity

C. Multiple simultaneous cranial nerve involvement

D. No refractory period

E. Paroxysms of pain

21. Answer E. (MN-9) Cranial neuralgias are painful entities that present with paroxysmal, electric shock–like pain in the distribution of a particular nerve. Compression (via ectatic vascular loops or tight cervical paraspinal musculature) and demyelination are possible etiologies. Triggers may include cutaneous stimulation, deep palpation, and swallowing. Typically, there is a refractory period in between triggered attacks of pain.

Facial pain disorders and painful cranial neuralgias are covered further in Chapters 9 and 57.

22. A 46-year-old woman with history of hyperlipidemia, migraines, coronary artery disease, cervical artery disease, and prior ischemic stroke presents with refractory status migrainosus. Which of the following treatments for migraine is the safest for this patient?

A. Dihydroergotamine

B. Ketorolac

C. Lidocaine

D. Prochlorperazine

E. Sumatriptan

22. Answer D. (MN-9) All of the listed treatments are effective in the management of intractable migraines; however, this patient has significant cardiovascular risk factors. Potent NSAIDs and lidocaine should be used with caution in patients with increased risk for cardiovascular events (eg, myocardial ischemia, ischemic stroke, arrhythmias). Ergot derivatives are contraindicated in patients with vaso-occlusive disease.

Treatment of migraine is covered in Chapters 9 and 56, with special focus during pregnancy covered in Chapter 129.

23. Following right ophthalmic aneurysm artery clipping, a patient notices decreased vision in the right eye. The dilated ophthalmoscopic examination is normal, and an MRI orbits does not show visual pathway pathology. There is a relative afferent papillary defect. The most likely etiology of vision loss is:

A. cerebral infarct

B. dry eyes

C. elevated intracranial pressure

D. ischemic optic neuropathy

E. somatoform disorder

23. Answer D. (MN-10) The afferent papillary defect indicates injury either in the ipsilateral optic nerve or contralateral optic tract. Since the visual disturbance occurred in the right eye following right ophthalmic artery manipulation, the injury must be to the ipsilateral optic nerve (Table 2.23.1). Acute retrobulbar optic nerve injury may not be associated with immediate changes in the anterior optic nerve appearance. Cerebral infarct or elevated intracranial injury would be unlikely to cause these specific isolated symptoms.

The afferent visual pathway, with common locations and causes of injury, is covered in Chapter 10. Acute ischemic stroke is covered further in Chapter 36. Intracranial pressure and neurocritical care monitoring are covered in Chapter 34 and further in Chapter 111.

TABLE 2.23.1 Signs and Symptoms That Suggest Location in the Visual Pathway

Location of Lesion Along Visual Pathway	Signs and Symptoms
Anterior segment of the eye	Blurred vision Glare or halos Foreign body sense in eye Correction with squinting, pinhole, or glasses Response to blinking Visible opacities on examination
Retina	Distortion (metamorphopsia) Regional flashes of light in one eye Circumscribed vision loss in one eye Prolonged recovery from light exposure Floaters Night blindness Purple, yellow, or green vision Visible abnormality on retina examination
Optic nerve	Regional vision loss in one eye Decreased brightness Decreased color saturation Relative afferent pupillary defect Optic nerve head abnormality on examination (cupping, pallor, or swelling)
Chiasm	Bitemporal hemianopia Pallor of both optic discs
Optic tract	Homonymous hemianopia Optic atrophy Relative afferent pupillary defect in contralateral eye
Lateral geniculate nucleus (thalamus)	Incongruent partial homonymous hemianopia or full homonymous hemianopia Optic atrophy
Optic radiations	Homonymous hemianopia “Pie-in-the-sky” hemianopia, temporal lobe “Pie-on-the-floor” hemianopia, parietal lobe Optokinetic defect ipsilateral to parietal lobe lesion Hemiparesis, aphasia, alexia, agnosia, somatosensory disturbance
Occipital lobe	Homonymous quadrantanopia or hemianopia Sparing central vision Central hemianopia (scotomatous) Preserved temporal crescent of hemianopic visual field
Oculomotor/vestibular system	Oscillopsia Diplopia
Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

24. A 25-year-old soldier is seen 2 months after a closed head injury. Neuroimaging is normal. He has vertical diplopia due to a left fourth nerve palsy. Which will make his double vision worse?

A. Primary gaze

B. Right gaze

C. Right tilt

D. Upgaze

24. Answer B. (MN-10) The fourth nerve supplies the superior oblique, which moves the ipsilateral eye superiorly in adduction, while internally rotating or “intorting” the eye. Therefore, the imbalance is most symptomatic in contralateral gaze, downgaze, and ipsilateral tilt. This latter effect is due to the torsional action of the superior oblique.

Traumatic cranial neuropathies, including trochlear neuropathy, are covered further in Chapter 49.

25. A 22-year-old man is brought to the ED after a car accident in which he changed lanes and hit an adjacent car. He did not hit his head or lose consciousness. He reports that he has had some problems with vision in his right eye for several months, but he has not had the time to see a doctor. On examination, his visual acuity is 20/100 in the right eye and 20/20 in the left eye. He has a right relative afferent pupillary defect (APD). The funduscopic examination is normal in both eyes. Automated perimetry reveals a superior temporal field defect in the left eye and a cecocentral scotoma in the right eye. Which of the following is the most likely diagnosis?

A. Occipital lobe infarction due to vertebral artery dissection

B. Optic nerve glioma

C. Orbital apex meningioma

D. Pituitary adenoma

E. Traumatic optic neuropathy

25. Answer D. (MN-10) He has an ipsilateral (right, in this case) optic neuropathy and contralateral superior temporal field defect, known as a junctional scotoma. This is most consistent with an injury to the anterior/inferior section of the ipsilateral optic chiasm, known as Wilbrand knee. A lesion to this area injures both the ipsilateral optic nerve as it enters the chiasm and the crossing inferonasal fibers from the contralateral optic nerve that cross briefly into the ipsilateral optic nerve before arching back into the ipsilateral optic tract. Lesions to the optic chiasm are common complications of pituitary tumors. An orbital apex tumor or optic nerve glioma would present with monocular vision loss in addition to ipsilateral cranial nerve III, IV, V₁, and VI deficits, without a contralateral visual field deficit. Traumatic chiasmal neuropathies are rare, and this patient’s symptoms preceded his accident. An occipital lobe infarction would cause a contralateral homonymous hemianopia without an APD.

An optic nerve glioma is demonstrated further in Figure 145.3. Acute ischemic stroke of the posterior cerebral artery is covered further in Chapter 36.

26. A patient has anisocoria immediately following a surgical procedure. The left pupil is smaller, and the difference is more pronounced in a dark environment. The patient cannot be suitably aroused to assess for ptosis. The most likely surgery was:

A. craniotomy to decompress left hemisphere subdural hematoma

B. decompression of a right cerebellopontine angle tumor

C. left carotid tumor resection

D. physiological anisocoria

E. right PCOM aneurysm clipping

26. Answer C. (MN-10) Anisocoria more pronounced in dark indicates poor dilation of the small pupil due to sympathetic injury, ie, Horner syndrome. Of the answer choices, carotid manipulation is the only one to cause injury to the sympathetic pathway, as the sympathetic chain runs along the carotid artery from the level of the superior cervical ganglion until the entry of the fibers through skull foramina. Anisocoria more pronounced in light indicates failure of pupillary constriction in the larger pupil due ipsilateral cranial nerve III injury, which may be secondary to mechanical compression of this nerve.

Traumatic arterial dissection and vascular injuries are covered further in Chapters 9 and 36.

27. A patient complains of vertical diplopia. The eyes appear aligned by light reflection. You ask the patient to fixate on a distant object. When you cover the right eye the left eye moves inferiorly. When you switch the cover to the left eye, the right eye moves superiorly. This is consistent with:

A. exotropia

B. esotropia

C. left hypertropia

D. right hypertropia

27. Answer C. (MN-10) Cover testing is a useful way to measure ocular misalignment in an awake patient. The covered eye drifts in the direction of misalignment. Exposing that eye results in a compensatory saccade that is easily observed. In this case the left eye saccades down, indicating that it was high.

The examination of extraocular movements is covered further in Chapter 4.

28. A 40-year-old woman presents with right eye pain for 3 days with diplopia and decreased right eye vision starting that morning. Her vision is 20/60 with the right eye and 20/20 with the left. She has partial III, IV, and VI nerve palsies on the right. There is decreased forehead sensation on the right. Cheek and chin sensation are symmetric. This is concerning for a lesion in which of the following?

A. Brainstem

B. Cavernous sinus

C. Neuromuscular junction

D. Orbital apex

E. Superior orbital fissure

28. Answer D. (MN-10) Ipsilateral vision loss (suggesting cranial nerve II involvment) in addition to cranial nerve III, IV, V₁, and VI palsy localizes to the orbital apex. Cranial nerve II does not localize to the cavernous sinus or superior orbital fissure; thus, one would not expect vision loss from a lesion in these areas. Cavernous sinus lesions may classically impact cranial nerves III, IV, VI, V₁, and V₂. Lesions in the superior orbital fissure will impact III, IV, VI, and V₁ only.

The cavernous sinus syndrome is covered further in Chapter 10, with cavernous sinus thrombosis covered in Chapter 9.

29. A patient has bilateral posterior cerebral artery infarcts. What would you expect the visual field to look like?

A. Constricted with preserved central acuity

B. Diffusely decreased with decreased central acuity

C. Inferior greater than superior constriction in both eyes

D. Normal

29. Answer A. (MN-10) PCA strokes spare the occipital pole and central vision. Bilateral strokes will therefore spare central visual fields on both sides while compromising peripheral vision in both hemifields (Figure 2.29.1).

Acute ischemic stroke is covered further in Chapter 36.

FIGURE 2.29.1 (Adapted with permission of Elsevier Science & Technology Journals from Marshall RS, Mayer SA. On Call Neurology. 3rd ed. Saunders; 2007; permission conveyed through Copyright Clearance Center, Inc.)

30. A 50-year-old woman presents with bilateral ptosis and abduction deficits. Pupils are equal and reactive. When you ask her to maintain upgaze the ptosis worsens. The most likely etiology is:

A. bilateral cavernous sinus disease

B. bilateral partial third and complete VI nerve palsies

C. myasthenia gravis

D. pontine infarct

E. thyroid orbitopathy

30. Answer C. (MN-10) The presence of multiple extraocular movement palsies that worsen with sustained effort in the setting of normal pupillary reactivity is one of the hallmarks of myasthenia gravis. The fluctuation of the patient’s ptosis and preserved eye adduction is more suggestive of a neuromuscular junction problem as opposed to a complete third nerve palsy. Furthermore, there is no single anatomic localization for bilateral ptosis and bilateral abducens palsies. A pontine infarct cannot explain this pattern of deficits in isolation.

Myasthenia gravis and other disorders of the neuromuscular junction are covered in Chapter 93. Acute ischemic stroke is covered further in Chapter 36.

31. A 75-year-old man has been admitted for altered mental status. He otherwise has a past medical history of hypertension, depression, coronary artery disease, and type 2 diabetes mellitus. He is agitated, disoriented, and pulling at his intravenous lines. What is the first step in managing his agitation?

A. Make sure the patient, family, and staff are safe, and if not, apply restraints (chemical or physical) as needed

B. Order a CBC, BMP, liver enzymes, UA to rule out other causes of altered mental status

C. Order midazolam for delirium treatment

D. Request a psychiatry consult to assist in management of altered mental status

E. Start a detailed history and physical examination; review medication administration

31. Answer A. (MN-11) The patient should first be assessed for safety before any other diagnostics or treatments are begun (Table 2.31.1). Once the patient and staff are safe, then the workup for altered mental status can continue. Choices B and E are appropriate for further workup after the patient is safe. Choice C is incorrect as midazolam is not a treatment for delirium and is associated with worse outcomes in this population. Choice D may be appropriate but should occur as an adjunct, if needed, to initial diagnostic testing and medical management.

Aside from the approach to diagnosing delirium (Chapter 11), the topic is covered in multiple places in the text book including sepsis-associated encephalopathy (Chapter 120), in association with organ transplantation (Chapter 130), in alcohol withdrawal (Chapter 131), and in the context of psychosis and psychiatric disease (Chapter 153).

TABLE 2.31.1 Management Strategies for Delirium

Ensure patient and staff safety. Pharmacologic management may be required in patients whose agitation may harm themselves or others.

Rule out emergent causes of mental status change such as hypoxia, hypercarbia, drug withdrawal, seizures, cerebral edema, and new/worsening stroke.

Perform focused history and physical examination including assessment of arousal level.

Assess delirium with tools such as the confusion assessment method or confusion assessment method for the intensive care unit.

Removal of catheters/restraints; promote sleep; perform early mobilization; glasses and hearing aids; eliminate unnecessary alarms and stimuli; medication review.

Light sedation strategies with avoidance of benzodiazepines

Establish a calm, reassuring environment and promote human contact, especially with loved ones.

Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

32. The patient above is safely restrained. His neurological workup, including brain imaging, is unremarkable, and he is found to have a urinary tract infection and started on antibiotics. What is the most appropriate next step in treatment of his delirium?

A. Make patient NPO to avoid aspiration

B. Request a psychiatry consult

C. Start an antipsychotic medication such as haloperidol

D. Start intravenous dexmedetomidine for rapid control of delirium

E. Try nonpharmacological interventions such as reorienting strategies, promoting a regular sleep-wake cycle, providing hearing aids and glasses as needed, and encouraging visits of familiar persons

32. Answer E. (MN-11) In addition to maintaining patient safety, nonpharmacological interventions should be the first-line treatment in all patients with delirium while the underlying cause is treated. Choices C and D may provide rapid symptomatic relief, but no randomized study has found pharmacological interventions to be superior to nonpharmacological interventions. Choice B is reasonable, although it should not come before institution of universal measures to treat delirium. Although a patient may need to be placed NPO for their safety, this intervention would not treat their delirium (Table 2.31.1).

In the context of psychosis related to primary psychiatric disease the use of antipsychotic medications is covered in Chapter 153.

33. A 56-year-old woman is admitted with concern for stroke. She has a history of diabetes mellitus type 2, obesity, sleep apnea, and hypertension. On hospital day 3 she is found to be oriented to self only, anxious, although redirectable without cranial nerve deficit or focal weakness. She has a Foley catheter in place and has been placed in soft wrist restraints, and her television is on, although the patient is not watching it. What is the next best step?

A. A dexmedetomidine drip

B. Intravenous haloperidol

C. Remove Foley catheter and restraints, turn off the television, open shades to establish a day/night cycle, and reorient the patient as needed

D. Repeat brain imaging

E. Sedation with a benzodiazepine

33. Answer C. (MN-11) The patient is delirious but calm, redirectable, and not an immediate danger to herself or others; therefore, neither restraints nor emergent pharmacological therapy are needed. Nonpharmacological interventions, such as removal of excess tubes and lines, as well as turning off unnecessary environmental stimulation, frequent reorientation, and establishing good day/night hygiene should be first line in the management of delirium. Repeat brain imaging is not needed given the examination is more consistent with encephalopathy than focal neurological deficit. Benzodiazepines should be avoided in delirium.

Cerebrovascular diseases are covered in detail throughout Section V.

34. A patient on day 12 of hospitalization currently has delirium. The family wants to know what if any are the implications of this condition. Which of the following outcomes is most associated with delirium?

A. Increased risk of stroke

B. Increased mortality

C. Increased risk of epilepsy

D. Increased risk of frontotemporal dementia

E. All of the above

34. Answer B. (MN-11) Delirium has been shown to increase hospital length of stay, morbidity, mortality, and cognitive impairment, at least in the immediate period following delirium. Various causes of delirium, particularly acute and chronic infections, have been demonstrated to increase the risk of subsequent dementia, possibly specifically the expression of Alzheimer disease. While delirium can be seen in persons with frontotemporal dementia, epilepsy, or stroke, it is not known to be a risk factor for increasing the incident risk of these diseases.

Alzheimer disease and other dementias are covered in Section VII.

35. A 65-year-old man is admitted to the ICU after a ischemic stroke. He is intubated and sedated with fentanyl and midazolam drips. He appears to have adequate pain control, is calm, and has a score on the Richmond Agitation and Sedation Scale (RASS) of −2 (reflecting light sedation, with brief awakening to voice with eye opening and eye contact lasting less than 10 seconds). Which statements below are true in regards to this patient’s care?

A. Fentanyl drip should be discontinued

B. Midazolam should be reduced or discontinued in favor of a different sedative such as propofol or dexmedetomidine

C. The CAM-ICU (Confusion Assessment Method for the intensive care unit) screening tool cannot be used on this patient because he is intubated

D. The patient has a satisfactory level of sedation

E. The patient’s RASS score is adequate, and no change in sedation or analgesia is needed

35. Answer B. (MN-11) Midazolam is an independent risk factor for delirium and should be discontinued if a more appropriate agent is available. Propofol and dexmedetomidine are reasonable alternatives given their short half-lives and less propensity to exacerbate delirium. While opiates can exacerbate delirium, fentanyl drip is reasonable for initial management of analgesia in a patient who was recently intubated. Moreover, the patient’s pain control is adequate; thus, the fentanyl drip should not be abruptly discontinued. The patient is a RASS-2 Table 2.35.1, which means he is sedated deeper than the ideal RASS of 0. Thus sedation should be lightened in this patient to reduce the risk of delirium. The CAM-ICU is a validated scale for assessing delirium in intubated patients (Table 2.35.2).

Cerebrovascular diseases are covered in detail throughout Section V.

TABLE 2.35.1 Richmond Agitation-Sedation Scale

Score	Term	Description
+4	Combative	Overly combative, violent, immediate danger to staff
+3	Very agitated	Pulls or removes tube(s) or catheter(s); aggressive
+2	Agitated	Frequent or nonpurposeful movements, fights ventilator
+1	Restless	Anxious but movements not aggressive/vigorous
0	Alert and calm
−1	Drowsy	Not fully alert but has sustained awakening (eye opening/eye contact) to voice >10 s
−2	Light sedation	Briefly awakens with eye contact to voice (<10 s)
−3	Moderate sedation	Movement or eye opening to voice (but no eye contact)
−4	Deep sedation	No response to voice but movement or eye opening to physical stimulation
−5	Unarousable	No response to voice or physical stimulation
Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

TABLE 2.35.2 Confusion Assessment Method for the Intensive Care Unit (CAM-ICU)

Feature A plus B and either C or D present = CAM-ICU positive
A. Acute onset of fluctuating course	• Is the patient different than their baseline? or • Has the patient had any fluctuation in mental status in the past 24 h?
B. Inattention	• Letters attention test: Say to the patient, “I am going to read to you a series of 10 letters. Whenever you hear the letter ‘A,’ indicate by squeezing my hand.” SAVEAHAART or CASABLANCA or ABADABADAAY Errors are counted when patient fails to squeeze on the letter “A” and when patient squeezes on any letter other than “A.” If greater than two errors, patient has inattention.
C. Altered level of consciousness	• Present if the RASS score is anything other than alert and calm or RASS 0.
D. Disorganized thinking	• Ask patient yes/no questions:
		1. Will a stone float on water? 2. Are there fish in the sea? 3. Does 1 lb weigh more than 2 lb?
	Errors are counted when the patient incorrectly answers a question • Have the patient follow commands: Say to patient “Hold this many fingers up.” (Show two fingers to patient.) Have them repeat with the other hand using a different number of fingers. An error is counted if patient is unable to complete the entire command. If patient makes greater than one error, then they are positive for this feature.
RASS, Richmond Agitation-Sedation Scale.
Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

36. Over the past year, a 74-year-old man has become irritable with his wife and generally dissatisfied with getting older including his retirement, which he had looked forward to for many years. Six months ago he began losing control of his urine, without a urological explanation including normal prostatic function. Over the same period his family has noticed that his pace has slowed, often asking others to wait for him to catch up with them. On examination, he is somewhat irascible, is consistently slow in his responses during the interview, and has difficulty with serial subtractions. His gait is noticeable for consistently small steps, appearing stuck to the floor, but not changing as he passes through doorways. He has no other evidence of parkinsonism on examination, including no retropulsion, stooping, tremor, or rigidity. An MRI suggests ventricular enlargement.

What is the most appropriate next diagnostic test?

A. Amyloid positron emission tomography scan (Amyloid-PET)

B. Apolipoprotein E (APOE) genotyping

C. Dopamine imaging ioflupane ¹²³I (DaTscan)

D. Fluorodeoxyglucose positron emission tomography scan (FDG-PET)

E. Large-volume lumbar puncture with stride length/gait speed measured before and after the procedure

36. Answer E. (MN-12) The development of clinical-biological definitions of dementia has aided in more specific diagnoses, but patients may have clinical features suggesting several diagnoses, often reflecting an increasing frequency of multiple biological changes when complex overlapping features are present. The patient’s clinical history and examination are most supportive of normal pressure hydrocephalus (NPH). Assessment of gait before and after large-volume lumbar puncture is the most direct means of establishing a diagnosis. A DaTscan may be considered in the workup of a patient with dementia with parkinsonism (including PDD, DLB, or PSP in which it may be positive). Recognizing that a degenerative copathology is frequently present with NPH, additional biomarker-based assessments, including nuclear medicine and biofluid assessments, at present can most often help in determining the probability that AD or related neurodegenerative dementias (FTD or DLB) are present. Anticipating the workup for NPH includes cerebrospinal fluid sampling, assays for beta-amyloid, phosphorylated and total tau, and alpha-synuclein may be advisable. These are becoming part of a growing list of CSF biomarkers in dementia. Amyloid-PET is most often positive in AD or CAA. APOE genotyping is not indicated in the workup of NPH but may have a role in determining the risk of complications of emerging antiamyloid infusion therapies.

Dementia is covered throughout Section VII. NPH is covered further in Chapters 87 and 110. Brain nuclear medicine imaging is covered in Chapter 23.

37. A 74-year-old man working as an executive in a family real estate firm gradually becomes clumsy when writing with his right hand, often making letter transposition errors. Over the past year his children have gradually taken over his job responsibilities given his inability to complete tasks and recall pertinent details of his business. His family thinks he has become depressed over the past few months, content to be idle at home rather than run his business. His manner of dress has become a bit askew after being known lifelong to be meticulous in his composure. He has a minor car accident after failing to see a car approaching from his right. On examination, he is somewhat emotionally vacant, with poor short-term memory and recall, right hemineglect, and right hand dyspraxia without evidence of alien limb.

What is the most likely diagnosis?

A. B₁₂ deficiency

B. Corticobasal ganglionic degeneration

C. Corticobasal syndrome due to Alzheimer disease

D. FTD-ALS

E. Parkinson disease dementia

37. Answer C. (MN-12) The patient has a clinical history most supportive of corticobasal syndrome (CBS) due to Alzheimer disease (AD). AD presents with a range of cognitive and behavioral symptoms beyond the classic amnestic syndrome (Table 2.37.1), and the majority of patients with CBS have underlying AD pathology. Patients with this disease, in addition to progressive asymmetric rigidity, apraxia, and cortical sensory loss, display prominent memory and visual spatial impairment due to medial temporal and parietal lobe degeneration. Corticobasal ganglionic degeneration (CBD) placed in the spectrum of frontotemporal dementia (FTD, Figure 2.37.1) is far less common than corticobasal syndrome seen in persons with pathological or biomarker evidence of Alzheimer disease. Like other forms of FTD, CBD tends to present at younger age and may co-occur with other FTD features including behavioral changes and aphasia. Parkinson disease dementia, B₁₂ deficiency, and FTD-ALS are not otherwise supported by the history.

Alzheimer disease is covered further in Chapter 51, and frontotemporal dementia is covered further in Chapter 52.

TABLE 2.37.1 Ten Warning Signs of Alzheimer Disease

1. Memory loss that affects job skills

2. Difficulty performing familiar tasks

3. Problems with language

4. Disorientation to time and place

5. Poor or decreased judgment

6. Problems with abstract thinking

7. Misplacing things

8. Changes in mood or personality

9. Problems with directions or spatial relations

10. Loss of initiative

Adapted from the Alzheimer’s Association. 10 early signs and symptoms of Alzheimer’s. Alzheimer’s Association Web site. Accessed October 15, 2020. https://www.alz.org/alzheimersdementia/10_signs

FIGURE 2.37.1 (Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.)

38. A 48-year-old man working as a high school math teacher becomes disinhibited in his classroom in the new year, verbally lashing out at students when becoming impatient. He has become content to arrive to work late after being highly reliable and running his local faculty union from which he unexpectedly resigned at the end of the prior school year. His family has found him increasingly difficult to be around at home, and his wife is considering divorce after perceiving an impenetrable emotional distance has developed between them. His 54-year-old sister died last year of amyotrophic lateral sclerosis, and many have presumed his changes are reflective of that grief. On presentation to a neurologist, he is disinhibited and easily angered by his family’s concern of cognitive impairment. He struggles to answer simple calculation tasks despite his profession and threatens to leave the office when he perceives cognitive testing has endured too long. An MRI is performed and reveals frontal and temporal atrophy, along with parietal atrophy.

Which genetic test is likely positive?

A. Amyloid precursor protein (APP)

B. APOE epsilon 4/4 haplotype

C. Chromosome 9 Open Reading Frame 72 (C9ORF72) hexanucleotide repeat expansion

D. Glucocerebrosidase (GBA)

E. Presenilin 1 (PSEN1)

F. Triggering Receptor Expressed on Myeloid Cells 2 (TREM2)

38. Answer C. (MN-12) This patient and family are most likely affected by a gene causing FTD and ALS, with the most common one being C9ORF72 (Figure 2.38.1). Choice D is identified in family members of those with Parkinson disease dementia (PDD) or Dementia with Lewy bodies (DLB). TREM2 is an incompletely penetrant Alzheimer disease gene, as is APOE. APP and PSEN1 are highly penetrant autosomal dominant Alzheimer disease genes. The diagnostic approach to persons with dementia is shown in Table 2.38.1, typically beginning with history and examination, moving to exclusion of reversible causes, and then to biomarker-based characterization of disease. Biological characterization has become increasingly important to determine potential candidacy for the growing list of disease-modifying treatments for neurodegenerative dementias.

Alzheimer disease is covered further in Chapter 51, and frontotemporal dementia is covered further in Chapter 52. Genetic testing in neurological disorders is covered further in Chapter 35.

FIGURE 2.38.1 (Adapted from Ling SC, Polymenidou M, Cleveland DW. Converging mechanisms in ALS and FTD: disrupted RNA and protein homeostasis. Neuron. 2013;79(3):416-438. Copyright © 2013 Elsevier. With permission.)

TABLE 2.38.1 Practice Parameters for Diagnosis of Dementia

Clinical Evaluation

History from patient and an informant

Cognitive assessment—mental status examination

Neuropsychological testing (when above is insufficient for confident diagnosis)

Routine Testing

Complete blood cell count

Serum chemistry—electrolytes, glucose

Serum BUN, creatinine, liver function tests

Serum TSH and B₁₂ levels

Serologic tests for syphilis and HIV (optional—depending on risk)

Biomarkers

Measures of brain atrophy, infarction, and structural changes

Brain MRI

Measures of neurodegeneration or neuronal injury

CSF total tau measurement

FDG-PET

MRI regional volumes and gray matter thickness

Measures of β-amyloid

CSF β-amyloid measurement

PET amyloid imaging

Measures of neurofibrillary tangles

CSF phospho-tau measurement

PET tau imaging

Measure of dopaminergic dysfunction

Ioflupane SPECT scan

Genetic tests (depending on age, family history, and clinical presentation)

AD mutations: PS1, PS2, APP

FTD mutations: tau, C9orf, progranulin

Prion protein mutations

Other mutations

AD, Alzheimer disease; APP, amyloid precursor protein; BUN, blood urea nitrogen; C9orf, chromosome 9 open reading frame; CSF, cerebrospinal fluid; FDG, 18F-fluorodeoxyglucose; FTD, frontotemporal dementia; HIV, human immunodeficiency virus; MRI, magnetic resonance imaging; PET, positron emission tomography; PS1, presenilin 1; PS2, presenilin 2; SPECT, single photon emission computed tomography; TSH, thyroid stimulating hormone.

This table is based on first practice guidelines published by the American Academy of Neurology (2001), more recent National Institute on Aging-Alzheimer’s Association Workgroup recommendations (2011), and other practice guidelines.

39. A 74-year-old man, retired 10 years from being a professional opera singer, develops forgetfulness over the course of the past year. His wife has noticed that he has substantially slowed down his pace of walking and lost animation in his previously expressive face over the past few months. Curiously, he has begun acting out some of his well-known performances in his sleep. Last week he became convinced that their knotty pine floors were covered with cockroaches and spent an hour unsuccessfully cleaning the floor. Quite striking is also the case that some days his cognition is remarkably clear and stands in stark contrast to his more profoundly affected, impaired days. A workup for reversible causes of dementia is unremarkable and MRI brain is normal.

What diagnostic test is indicated at this time?

A. Apolipoprotein E (APOE) genotyping

B. CSF study for amyloid and tau

C. Dopamine transporter (DAT) scan

D. No further workup is indicated

E. Polysomnography

39. Answer D. (MN-12) This patient’s clinical symptoms are consistent with Lewy body dementia (DLB). The clinical features for DLB include dementia, hallucinations, fluctuations in level of consciousness, and REM sleep disorder. No further workup is necessary. Although a DaTscan may be positive, it would not change the diagnosis. Profiling CSF beta-amyloid and tau is most useful in confirming a diagnosis of Alzheimer disease. In DLB this assay may be normal, or amyloid may be slightly low in such patients. Amyloid PET may be considered in some patients with a clinical history supportive of Alzheimer disease. Polysomnography may demonstrate REM sleep behavior disorder, but this was already apparent in the history.

Sleep studies are covered further in Chapter 30. Lewy body dementias are covered in Chapter 53.

40. A 54-year-old executive director of a small company has some concerns about her memory, which only emerges on rare occasion on days when she is multitasking or preparing for a major event. She has sought a comprehensive evaluation at a preventative health center, which has included an assessment of coronary artery calcium and an amyloid-PET scan among other tests. Her amyloid-PET is questionably positive and neuropsychological testing done thereafter revealed no deficits, and if anything she did better than expected. How do you interpret the amyloid PET?

A. A positive FDG-PET would confirm the diagnosis of AD

B. For clinical purposes, the amyloid-PET cannot be interpreted in this context

C. Her diagnosis is likely amnestic MCI

D. She definitely has Alzheimer disease based on the amyloid-PET

40. Answer B. (MN-12) This patient is cognitively normal. A positive amyloid-PET scan is not definitive for Alzheimer disease; this test is a diagnostic tool to detect the presence of amyloid plaques in the brain as a biomarker to aid in the clinical diagnosis in a patient with cognitive decline. There is no evidence provided in the vignette to support other biological features of Alzheimer disease such as tau or neurodegeneration. Although the field of dementia is evolving toward establishing a clinicobiological definition on as many patients as possible, there are no disease-modifying pharmacotherapies available for persons without clinical symptoms and at present amyloid screening is not advisable.

Nuclear medicine imaging is covered in Chapter 23.

41. A 61-year-old man has developed concerns about his declining memory over the past year, impacting his ability to teach his class as well as he did in the past. In particular, he has trouble remembering the names of his new students each semester and has some difficulty responding to questions asked of him in class if they are bundled together. However, he is still highly regarded for his teaching skills. Otherwise, he remains able to manage all of his affairs independently without error or difficulty. Nonetheless, his memory loss has become so substantial that he seeks your help. Workup has revealed impaired delayed recall on cognitive testing and slight cortical atrophy without distinct pattern. CSF reveals low amyloid beta, with elevated phospho-tau and total tau, along with negative prion RT-QuIC and 14-3-3.

What is your interpretation of the results?

A. Creutzfeldt-Jakob disease (CJD)

B. Dementia with Lewy bodies (DLB)

C. Frontotemporal dementia (FTD)

D. MCI due to Alzheimer disease

E. Mild cognitive impairment (MCI) with depression

41. Answer D. (MN-12) This patient has MCI, based on both subjective and objective evidence of cognitive impairment. His overall cognitive function and ability to perform activities of daily living are preserved. His biomarker profile and low amyloid beta, with elevated phospho-tau and total tau, are all strongly supportive of Alzheimer disease. Based on this he may be a candidate for an emerging biological disease-modifying therapy for Alzheimer disease. FTD may have normal CSF biomarkers or slightly elevated tau or phospho-tau. DLB may have normal CSF biomarkers or slightly low amyloid. CJD is not consistent with the clinical history, and its biomarker is typically very high CSF tau and positive RT-QuIC and 14-3-3 protein.

Mild cognitive impairment is covered in Chapter 50, Alzheimer disease is covered in Chapter 51, and Creutzfeldt-Jakob disease (CJD) is covered in Chapter 55.

42. A 73-year-old woman has had progressive memory loss and impaired language fluency over the past 3 years leading to her family to take over the responsibility of bill payment. A workup has suggested Alzheimer disease. What MRI abnormalities are most likely to be seen in this patient?

A. Bilateral basal ganglia hyperintensities on T2-weighted imaging

B. Bilateral frontal lobe atrophy

C. Bilateral parietal and medial temporal atrophy along with bilateral parietal subcortical white matter hyperintensities

D. Cortical ribboning on DWI

E. Left inferior division middle cerebral artery infarction

42. Answer C. (MN-12) This pattern is most consistent with Alzheimer disease, with or without the white matter changes. Some patients with Alzheimer disease may have normal structural brain imaging but with functional changes on FDG-PET or related imaging. DWI ribbon pattern is seen in Creutzfeldt-Jakob disease. The patient does not have evidence of a stroke or rapidly progressive dementia. Bilateral frontal atrophy is typical of frontal temporal dementia, although it can be seen rarely as a variant of Alzheimer disease, but is not supported by the clinical history. In the frontal variant of Alzheimer disease, patients classically display prominent personality and changes with frontal lobe atrophy on imaging subsequent to initial memory dysfunction. Bilateral basal ganglia lesions are likely reflective of an acute toxic metabolic insult as opposed to chronic neurodegenerative process.

43. A 48-year-old man presents for evaluation of low-amplitude continuous movements of his arms, which have developed and progressively worsened over the last 2 years. They are smooth, follow an irregular path, and involve the entire arm, and the patient is unable to significantly suppress them voluntarily. They occur at unpredictable times including at rest and with action. He denies any specific urge to move his arm, it happens involuntarily; however, they are bothersome. His friend has observed these movements and describes them as fidgeting. Which type of movement best describes what he is experiencing?

A. Action tremor

B. Akathisia

C. Chorea

D. Hyperekplexia

E. Myoclonus

43. Answer C. (MN-13) The features listed all describe choreiform movements. Myoclonus involves abrupt muscle contractions. Action tremor is not continuous, as it subsides at rest. Akathisia requires an underlying subjective urge to trigger the movement. Hyperekplexia describes abrupt movements that are specifically triggered by an external stimulus, in the context of an underlying disorder of inhibitory neurotransmission mediated by impaired glycine receptors.

44. Which tool is the most sensitive and specific when attempting to make a diagnosis of acute dystonic reaction to a medication?

A. Careful history and neurologic examination

B. Lumbar puncture/CSF analysis

C. MRI of the brain with contrast

D. Serum dopamine levels

E. Urine toxicology screening

44. Answer A. (MN-13) Diagnosis of most abnormal movements is made on the basis of a detailed history and examination, although other testing may be supportive in understanding an underlying etiology.

45. Which of the following clinical features best differentiates choreoathetosis from ballism?

A. Amplitude

B. Anatomic area involved

C. Rhythmicity

D. Velocity

E. Voluntary suppressibility

45. Answer D. (MN-13) Velocity. Of all the choices, only velocity uniquely distinguishes ballism from chorea. Typical features of ballism are high-velocity movements and typically rapid large amplitude involving proximal muscles. Choreiform movements are decidedly slower and can range from small- to large-amplitude movements involving proximal or distal muscles. Predictable rhythmicity is a feature of tremor. Anatomic areas vary from patient to patient. Voluntary suppressibility is primarily a feature of tics, although some individuals living with Parkinson disease in early stages may be able to briefly suppress rest tremor.

46. A 34-year-old woman presents to the ED with complaints of bilateral proximal leg weakness and fatigue without any changes in bowel or bladder function. Which of the following findings on examination would prompt a more urgent inpatient workup and evaluation?

A. Bilateral ptosis

B. Diplopia with prolonged upgaze

C. Hyperreflexia

D. Neck flexor and extensor weakness

E. Time course of 1 month

46. Answer D. (MN-14) Neck flexor and extensor muscles (sternocleidomastoid, scalenes, longus colli) are innervated by the cervical spinal nerve roots and serve as a surrogate for diaphragmatic strength (Table 2.46.1). Thus, weakness in these muscle groups signal respiratory insufficiency and immediate inpatient workup and observation. New bulbar deficits, ie, difficulty swallowing and talking, should also raise immediate concern in the evaluation of new neurological symptoms.

Common causes of weakness are reviewed in Table 14.6. Neuromuscular disorders are covered in detail in Section XIII.

TABLE 2.46.1 Common Muscle Groups, Actions, and Innervation^a

Muscle	Peripheral Nerve	Nerve Root	Action
A. Muscles of the Back, Shoulder, and Neck
Sternocleidomastoid	Spinal accessory	CN, XI, C2, C3	Contralateral rotation of the head
Trapezius	Spinal accessory	CN, XI, C3, C4	Shoulder elevation
Diaphragm	Phrenic	C3, C4, C5	Inspiration
Serratus anterior	Long thoracic	C5, C6, C7	Protraction and stabilization of scapula
Rhomboid	Dorsal scapular	C4, C5	Abduction and elevation of scapula
Levator scapulae	Dorsal scapular	C4, C5	Elevation of scapula
Supraspinatus	Suprascapular	C5, C6	Abduction of arm to 90°
Infraspinatus	Suprascapular	C5, C6	Lateral arm rotation
Deltoid	Axillary	C5, C6	Abduction of arm past 30°
Teres minor	Axillary	C4, C5	Medial arm rotation
Teres major	Subscapular	C5, C6, C7	Medial rotation and adduction of arm
Latissimus dorsi	Thoracodorsal	C6, C7, C8	Adduction of arm
B. Muscles of the Arm and Hand
Biceps brachii	Musculocutaneous	C5, C6	Forearm flexion with arm supinated
Brachialis	Musculocutaneous	C5, C6	Forearm flexion with arm pronated
Triceps brachii	Radial	C6, C7, C8	Forearm extension
Brachioradialis	Radial	C6, C7	Forearm flexion with arm supinated to 90°
Extensor carpi radialis	Radial	C6, C7	Hand extension
Supinator	Radial	C6, C7	Forearm supination
Extensor digitorum	Radial (PIN)	C7, C8	Extension of hand and digits two to five
Extensor carpi ulnaris	Radial (PIN)	C7, C8	Hand extension toward ulna
Abductor pollicis longus	Radial (PIN)	C7, C8	Thumb abduction
Extensor pollicis longus and brevis	Radial (PIN)	C7, C8	Thumb extension
Extensor indicis	Radial (PIN)	C7, C8	Index finger extension
Flexor carpi ulnaris	Ulnar	C7, C8, T1	Ulnar hand flexion
Flexor digitorum profundus	Ulnar	C8, T1	Flexion of distal phalanx of digits four and five
Adductor pollicis	Ulnar	C8, T1	Thumb adduction
Abductor digiti minimi	Ulnar	C8, T1	Abduction of fifth digit
Interossei	Ulnar	C8, T1	Finger abduction or adduction
Lumbricals three and four	Ulnar	C8	Flexion of proximal phalanx and extension of distal phalanx of digits four and five
Flexor carpi radialis	Median	C6, C7	Radial hand flexion
Pronator teres	Median	C6, C7	Forearm pronation
Flexor digitorum superficialis	Median	C7, C8, T1	Flexion of the middle phalanx of digits two to five
Abductor pollicis brevis	Median	C8, T1	Abduction of thumb at the metacarpal joint
Flexor pollicis brevis	Median	C8, T1	Flexion of thumb at the metacarpal joint
Opponens pollicis	Median	C8, T1	Thumb opposition
Lumbricals one and two	Median	C8, T1	Flexion of proximal phalanx and extension of distal phalanx of digits two and three
Flexor digitorum profundus	Median (AIN)	C7, C8	Flexion of distal phalanx of digits two and three
Flexor pollicis longus	Median (AIN)	C7, C8	Flexion of distal phalanx of the thumb
Pronator quadratus	Median (AIN)	C8, T1	Forearm pronation
C. Muscles of the Hip, Leg, and Foot
Iliopsoas	Femoral and nerve roots	L1, L2, L3	Hip flexion
Sartorius	Femoral	L2, L3	Hip flexion and lateral thigh rotation
Quadriceps femoris	Femoral	L2, L3, L4	Knee extension
Adductor longus, brevis, magnus	Obturator	L2, L3, L4	Thigh adduction
Gracilis	Obturator	L2, L3, L4	Thigh adduction
Obturator externus	Obturator	L3, L4	Thigh adduction and lateral rotation
Gluteus medius and minimus	Superior gluteal	L4, L5, S1	Thigh abduction and medial rotation
Tensor fasciae latae	Superior gluteal	L4, L5	Thigh abduction
Gluteus maximus	Inferior gluteal	L5, S1, S2	Hip extension
Biceps femoris (long head)	Sciatic	L5, S1, S2	Knee flexion
Biceps femoris (short head)	Sciatic (fibular)	L5, S1, S2	Knee flexion
Semitendinosus	Sciatic	L5, S1, S2	Knee flexion
Semimembranosus	Sciatic	L5, S1, S2	Knee flexion
Tibialis anterior	Fibular	L4, L5	Foot dorsiflexion
Extensor digitorum longus	Fibular	L5, S1	Extension of toes two to five
Extensor hallucis longus	Fibular	L5, S1	Great toe extension
Extensor digitorum brevis	Fibular	L5, S1	Toe extension
Fibularis longus and brevis	Fibular	L5, S1	Foot eversion
Tibialis posterior	Tibial	L5, S1	Foot inversion and plantarflexion
Flexor digitorum longus	Tibial	S2, S3	Flexion of toes two to four
Flexor hallucis longus	Tibial	S1, S2	Flexion of great toe
Gastrocnemius	Tibial	S1, S2	Foot plantarflexion
Soleus	Tibial	S1	Foot plantarflexion
Muscles of perineum	Pudendal	S2, S3, S4	Contraction of pelvic floor muscles
AIN, anterior interosseous nerve; CN, cranial nerve; PIN, posterior interosseous nerve.
^aThe nerve roots in boldface are the dominant roots involved in that particular muscle’s innervation.
Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

47. A 45-year-old man presents as an outpatient with complaints of right arm pain and numbness. On examination, there is weakness of the right deltoid, infraspinatus, supraspinatus, and biceps muscle. There is numbness along the distribution of the right lateral antebrachial cutaneous nerve. What would be the most likely localization?

A. Brainstem

B. C5 nerve root

C. Medial cord of the brachial plexus

D. Musculocutaneous nerve

E. Upper trunk of the brachial plexus

47. Answer E. (MN-14) The patient’s examination localizes to the upper trunk of the brachial plexus (C5-C6 nerve roots, Table 2.47.1, Figure 2.47.1) given involvement of the infraspinatus and supraspinatus muscles, which are innervated by the suprascapular nerve (C5-C6), and biceps brachii, which is innervated by the musculocutaneous nerve (C5-C7), and involvement of the lateral antebrachial cutaneous nerve, an extension of the musculocutaneous nerve. A C5 root lesion would not explain the patient’s symptoms, as there is no dorsal scapular nerve involvement, which would cause winging of the patient’s scapula. A brainstem injury would likely result in a more complex examination and may include cranial nerve deficits, hemibody weakness, and sensory loss and may involve signs that are crossed or contralateral to one another; sensory loss would also not be restricted to a single dermatome. The medial cord of the brachial plexus supplies the ulnar and median nerves and innervates the intrinsic muscles of the hand (Figure 2.47.1). The musculocutaneous nerve controls elbow flexion; thus, the injury cannot be localized to this nerve based on the patient’s motor deficits (Table 2.46.1)

Brachial plexus injuries are covered further in Chapter 49.

TABLE 2.47.1 Brachial Plexus Injuries, Mechanisms, and Presentation

Injury Classification	Mechanism of Injury	Clinical Presentation
Supraclavicular: roots, trunks	High-velocity injuries (eg, MVAs)	Motor and sensory loss in associated myotomes and dermatomes
Infraclavicular: trunks, terminal nerves	Penetrating injuries	Terminal branch deficits
Upper: C5-C6	Closed traction (shoulder is forcibly separated from head) Contact sports Prolonged operational positioning with contralateral rotation of head or upper extremity abduction greater than 90° Excessive traction to plexus during delivery	Erb palsy Weakness/paralysis of deltoid, biceps, brachioradialis, pectoralis major, supraspinatus, infraspinatus, subscapularis, teres major Loss of biceps reflex Hypesthesia in lateral arm and forearm “Waiter’s tip” position: Internal rotation of arm Extension and pronation of forearm Flexion of wrist and fingers
Lower: C8-T1	Thoracic surgery requiring median sternotomy Cervical rib and band syndrome Obstetrical trauma Pancoast tumor	Klumpke palsy Isolated hand paralysis Ipsilateral Horner syndrome Hypesthesia in medial arm and forearm and ulnar side of hand Atrophy of intrinsic hand muscles Loss of triceps reflex
MVA, motor vehicle accident.
Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

FIGURE 2.47.1 (Adapted with permission of Elsevier Science & Technology Journals from Marshall RS, Mayer SA. On Call Neurology. 3rd ed. Saunders; 2007; permission conveyed through Copyright Clearance Center, Inc.)

48. A 68-year-old man presents to your office with complaints of difficulty getting out of bed in the morning and changes in his gait. He feels his legs have become weaker over the past several months. In the presence of normal strength to confrontation, what finding on examination is most suggestive of corticospinal tract involvement?

A. A third cranial nerve palsy

B. Crossed adductors on testing the patellar reflex

C. En block turning with reduced arm swing when walking

D. Fatigable weakness

E. Reduced pinprick sensation in the entire right leg

48. Answer B. (MN-14) Upper motor neurons that form the corticospinal tract start in the primary motor cortex and synapse with interneurons and lower motor neurons within the anterior horn of the spinal cord. The majority of the upper motor neuron input is inhibitory; thus, patients with upper motor neuron injury classily have increased muscle tone, spasticity, and brisk reflexes with pathologic spread (ie, crossed adduction). The neurons of the corticospinal tract control motor activity and are not involved in sensation; thus, a lesion to the corticospinal tract in isolation would not explain the presence of sensory loss. Turning en block with reduced arm swing is suggestive of a basal ganglia pathology, such as Parkinson disease. Fatigable weakness is a key finding of neuromuscular junction disorders, particularly myasthenia gravis. A cranial nerve III lesion may be secondary to descending corticospinal/corticobulbar fibers in the midbrain.

Parkinson disease is covered in Chapter 86, and myasthenia gravis and other disorders of the neuromuscular junction are covered in Chapter 93.

49. A 72-year-old man presents with dysarthria and spasticity in muscles of the left upper and lower limbs. During walking, he is unable to initiate gait, and demonstrates poor guidance of his walking path. Where is the likely location of his lesion?

A. Anterior horn cell

B. Cerebellum

C. Motor tracts in the cerebral cortex

D. Spinal cord

49. Answer C. (MN-15) Upper motor lesions produce spasticity (velocity-dependent increase in muscle tone). The presence of dysarthria, along with limb dysfunction, indicates corticobulbar as well as corticospinal involvement; thus, the lesion is suggested to be unilateral and above the level of the spinal cord. In addition, cortical areas are involved in the control of activation and visual guidance of gait (Table 2.49.1) and may be further implicated clinically in this case.

TABLE 2.49.1 Neural Control of Gait

Region	Area	Function
Cortex	Motor areas	Volitional activation
	Motor areas	Visual guidance
	Limbic system	Emotional activation
Subcortical	Basal ganglia	Inhibition of postural tone
	Basal ganglia	Regulate rhythmic aspects of gait
	Cerebellum	Balance
		Limb coordination
		Adaptation
Brainstem	MLR	Initiation of locomotor pattern
Brainstem	PPN	Postural muscle tone
Spinal cord	Interneurons	Control locomotor pattern
MLR, midbrain locomotor region; PPN, pedunculopontine nucleus.
Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

50. A 65-year-old man presents with muscle rigidity, tremor in his distal upper limbs, difficulty with gait initiation, and short shuffling steps with occasional freezing episodes. Which part of the brain is likely involved?

A. Basal ganglia

B. Cerebellum

C. Neural networks originating in the cerebral cortex

D. Spinal cord

50. Answer A. (MN-15) Both rigidity and poor motor control (initiation and cessation of movement) are classic features of basal ganglia dysfunction. Moreover, the combination of rigidity, tremor, and bradykinesia, with short stride length, and freezing of gait are characteristics of Parkinson disease (Table 2.50.1).

Parkinson disease is covered in Chapter 86, as part of movement disorders (Section XII).

TABLE 2.50.1 Disorders of Gait

Disorder	Continuous Phenomena (Speed, Support Base, Arm Swing, Symmetry, Path)	Episodic Phenomena (Freezing of Gait, Gait Initiation, Falls)
High-Level Gait Disorders
Alzheimer disease Gait disorder occurs late in the disease.	Slow gait speed Short step length Increased time in double support Increased variability, particularly when performing cognitive dual task	Increased risk for falls
Mild cognitive impairment (MCI)	Slow gait speed Short step length Increased time in double support Gait variability higher in amnestic MCI but not in nonamnestic MCI Poor limb coordination (foot tapping) compared with controls	Increased risk for falls and fear of falls
Vascular dementia Gait disorder occurs early in the disease.	Slow gait speed Short step length Wide support base Rigidity	Freezing of gait Imbalance and falls seen
Normal pressure hydrocephalus Gait disorder seen early in the disease in conjunction with cognitive impairment and urinary incontinence	Slow gait speed Short step length Wide support base and outward rotation of foot (may be compensation for poor balance) Asymmetric steps Low step height (shuffling steps)	Increased risk for falls
Dementia with Lewy bodies Gait impairments seen in conjunction with visual hallucinations	Slow gait speed Reduced arm swing Flexed trunk posture Rigidity	Increased risk for falls
Frontotemporal dementia Gait impairments seen in the presence of behavioral disturbances (impulsivity, disinhibition)	Slow gait speed Involuntary trunk movements Postural instability	Increased risk for falls
Psychogenic (functional) gait disorder Gait impairments seen in the presence of psychiatric disorders such as anxiety, depression, or personality disorder	Gait impairments not consistent from one assessment to the next, may have sudden onset, very severe impairments at onset, and spontaneous remissions. Astasia-abasia Knee buckling during stance Wide support base and short step length (waddling) Excessive retropulsion	Tremor and dystonia seen, although may not be observed when the patient is distracted
Midlevel Gait Disorders
Hemiparesis	Slow gait speed Asymmetric stepping Swing phase—impaired lower limb moves in circumduction; hip hiking seen (Trendelenburg sign) Ankle may be maintained in plantar flexion and inversion leading to loss of heel strike at the beginning of stance. Stance phase—knee joint may hyperextend. Reduced arm swing on impaired side and reduced trunk rotation During dual-task gait, impairments worsen.	Increased risk for falls
Head trauma	Slow gait speed in the acute phase; resolves with time Increased time in double support may be seen Increased imbalance during tandem stance and gait Impairments more prominent during dual-task gait	Increased fall risk in the acute phase
Paraparesis	Slow gait speed Low cadence Low step height Circumduction may be seen. Decreased support base (scissoring gait) seen in patients with spasticity	Increased risk for falls due to weakness and imbalance
Parkinson disease Gait impairments seen in the presence of tremor, rigidity, and postural instability	Slow gait speed Very short step length Poor foot clearance during swing (which leads to shuffling gait) Increased temporal variability Postural instability and impaired balance seen (missteps during tandem gait) Stooped posture Limited or no arm swing During dual-task gait, patients with Parkinson disease pay greater attention to secondary cognitive task as opposed to gait leading to greater gait impairments (posture second strategy).	Freezing of gait Difficulty initiating gait Increased fear of falls and increased risk for falls as disease progresses
Multiple system atrophy Gait impairments seen in the presence of autonomic dysfunction and urinary incontinence	May present like Parkinson disease (slow speed, short step length) May present like cerebellar ataxia (gait ataxia—increased support base, path deviation, postural instability, impaired balance—missteps during tandem gait)	Increased risk for falls as disease progresses
Progressive supranuclear palsy	Postural instability Wide support base Rigid support base and low vertical displacement of the pelvis during gait Slow gait speed Difficulty turning (turn en bloc)	High risk for falls, increased fear of falls
Huntington disease	Slow gait speed Decreased step length Reduced cadence Increased time in double support Asymmetric step length Inconsistent step time Gait impairments worsen during secondary dual task. Chorea of limbs or trunk may increase instability. Dystonic posturing of ankle, trunk, neck, or arm during gait	Increased fear of falls and greater number of falls as disease progresses
Essential tremor	Slow gait speed Reduced cadence Increased time in double support Asymmetric step length Wide support base Increased temporal variability Prominent balance impairment (missteps during tandem gait)	Increased fear of falls and greater number of falls
Cerebellar ataxia	Inconsistent step time Asymmetric step length Short step length and low step height Wide support base Increased temporal variability Increased postural sway Greater missteps during tandem gait	High risk for falls, increased fear of falls
Low-Level Gait Disorders
1. Peripheral sensory disorders (peripheral neuropathy; posterior column disorder, vestibular and visual deficit)
Sensory ataxic gait	Wide support base Postural instability increased when standing with eyes closed Increased step height Short step length Foot slap at beginning of stance phase Patients tend to look at their feet while walking.	Increased risk for falls when not using vision
2. Peripheral *motor* disorders
Antalgic gait	Decreased weight bearing on painful limb leading to shorter stance phase Short stride length Reduced range of motion in affected joint(s) Trendelenburg sign may be seen due to pain at the hip joint.
Spinal muscular atrophy	Slow gait speed Decreased step length Reduced cadence Wide support base Trendelenburg sign Impairments worsen with fatigue during continuous walking.	Increased risk for falls
Duchenne muscular dystrophy	Lordotic posture and anterior pelvic tilt Waddling gait (short step length, wide support base) Knee hyperextension during stance Ankle plantar flexion during swing Gait pattern does not change with continuous walking.	Increased risk for falls
Reprinted with permission from Louis ED, Mayer SA, Noble JM, eds. Merritt’s Neurology. 14th ed. Wolters Kluwer; 2022.

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