12 Neurology for Neurosurgeons



10.1055/b-0039-171774

12 Neurology for Neurosurgeons



12.1 Electromyography and Nerve Conduction Studies (Nerve Conduction Velocity) (Table 12.1)










































Electromyography (EMG)


Normal


Abnormal


No electrical activity with muscle at rest




  1. Muscle at rest:


Spontaneous electrical activity with may be a sign of:




  • Denervation: fibrillation potentials and positive sharp waves (fibrillations may not be present in first 3 wk)



  • Myotonic disorders: waxing/waning frequency and amplitude and “dive bomber” sound on audio



  • Amyotrophic lateral sclerosis and progressive motor neuron disorders: fasciculations


Remember: Complex repetitive discharges are nonspecific (seen in both neuropathic and myopathic disorders)




  • B. Muscle in minimal (to identify recruitment pattern) and maximal contraction (interference pattern analysis):


    Motor unit action potentials reflect the number of motor units activated in contraction:




    1. Myopathy presents with decreased (amplitude/duration) motor unit action potential. Also, in myopathy, there is early/increased recruitment of motor units (the opposite happens in neurogenic conditions)



    2. Lower motor neuron disorder presents with increased (amplitude/duration) motor unit action potential


Nerve conduction velocity


Nerve


Conduction velocity 1


Distal latency


Median nerve


Sensory: ≥ 49 m/s


Motor: ≥ 49 m/s

4.5 ms


Ulnar nerve


Sensory: ≥ 49m/s


Motor: ≥ 43 m/s

3.7 ms


Peroneal nerve


Motor: ≥ 37 m/s

6.5 ms


NCV includes not only the study of the velocity of electrical stimulation but also the latency (time needed from stimulation to recording site in milliseconds) and the amplitude (the intensity of response measured in millivolts)



  • i. EMG and nerve conduction studies facilitate differential diagnosis between nerve dysfunction, muscle dysfunction, or dysfunction of neuromuscular transmission.



  • ii. Preganglionic vs. postgaglionic brachial plexus lesions: Sensory nerve action potential is normal in preganglionic lesions and reduced in postganglionic lesions. Consequently, it helps in diagnosing plexus disorders (reduced sensory potential with no fibrillations in paraspinal muscles) and root avulsion (typically normal sensory potential)



  • iii. Cervical roots can ONLY be evaluated C5 and below



12.2 Weakness (Table 12.2 )












































Disease

Presentation

Diagnostics

Treatment

Guillain–Barre 2




  • Weakness is:




    • symmetrical



    • primarily proximal



  • Usually occurs days weeks after respiratory/gastrointestinal infection (Campylobacter jejuni)


  1. Lumbar puncture: increased protein in CSF



  2. NCV: decreased


  1. Plasmapheresis



  2. Immunoglobulin therapy


Myasthenia




  • Weakness is worse at the end of the day



  • Commonly affects eyes (ophthalmoplegia/ptosis/diplopia), face, and swallowing ability


  1. Chest X-ray: rule out thymoma



  2. Tensilon test (edrophonium: no longer popular as it may cause life-threatening bradycardia): positive if muscles get stronger with Tensilon



  3. Nerve conduction study/EMG




  1. Acetylcholinesterase inhibitors (pyridostigmine/neostigmine)



  2. Immunosuppressants



  3. Removal of thymus



  4. Plasmapheresis



  5. IV immunoglobulin (in crisis)


Lambert–Eaton




  • Weakness:




    • improves with activity



    • primarily proximal



  • Dysfunction of autonomic system (dry mouth/constipation/blurred vision)



  • Usually occurs in the setting of paraneoplastic syndrome (frequently small cell lung cancer) 3




  1. EMG/NCV (compound motor action potentials and single-fiber examination)



  2. Antibodies against pre-synaptic voltage-gated calcium channels



  3. CT to find the cancer (small cell lung). If negative, it may have to be repeated within a few months. Consider bronchoscopy and PET


  1. Treat cancer



  2. Steroids



  3. Immunosuppressants


Polymyositis




  • Weakness is primarily proximal (shoulders and hips usually affected first)



  • Spares eyes



  • Muscle pain



  • Dysphagia



  • Increased risk of malignancy, heart failure, interstitiallung disease


  1. Increased creatine phosphokinase (CPK)



  2. EMG



  3. Positive muscle biopsy




  1. Steroids



  2. Immunosuppressants



  3. Physical therapy


Steroid myopathy




  1. Weakness is primarily proximal



  2. Associated with chronic use of steroids (ICU/asthma/chronic obstructive pulmonary disease/connective tissue disorders)



  3. In addition to chronic form, there is also an acute form (generalized weakness) associated with rhabdomyolysis

Vs


Epidural lipomatosis:




  • commonly associated with:




    • long-term steroid use



    • endogenous overproduction



    • obesity



  • Treatment:




    • Discontinue steroids



    • Weight loss



    • Surgery


  1. Discontinue or reduce steroids



  2. Physical therapy (not high intensity)

Note: When myopathy is suspected, investigate ability to stand up from chair/climb stairs.



12.3 Parkinson’s Disease and Parkinson Plus Syndromes (Table 12.3)






















































Disease

Presentation

Diagnostic

Other

Treatment


Symptoms common to all Parkinsonian syndromes:




  • Resting tremor



  • Rigidity (lead pipe or cogwheel)



  • Bradykinesia



  • Postural instability





Disease-specific symptoms


Parkinson’s disease




  • Starts out asymmetrical



  • Progressively:




    • Hypophonia



    • Dementia



    • Depression



    • Frequently alteration of smell


Degeneration of compacta substantia nigra + Lewy bodies (alpha-synuclein) 4




  1. L-Dopa (long-term use leads to dyskinesias)



  2. L-Dopa + Carbidopa (Sinemet: peripheral dopa decarboxylase inhibitor with less side effects) used primarily for freezing episodes



  3. Dopamine agonists (bromocriptine, pergolide, cabergoline): less effective than L-Dopa but with delayed risk of dyskinesias



  4. MAO-B inhibitors (selegiline)



  5. Surgery (deep brain stimulation): Patients with neuropsychiatric disorders are CONTRAINDICATED


Prognosis: Usually very good with treatment Often near-normal life expectancy


Progressive supranuclear palsy (Steele–Richardson–Olszewski syndrome)


  • Symmetrical



  • Reduced voluntary saccades (especially vertical and downward)



  • Poor response to L-DOPA

“Hummingbird” sign on MRI (atrophy of midbrain with preservation of pons)

Tauopathy


  1. No treatment



  2. Prognosis: death in 7 y (from pneumonia + swallowing difficulties)


Multiple system atrophy or Shy–Drager syndrome or olivopontocerebellar atrophy or striatonigral degeneration




  • Autonomic dysfunction (orthostatic hypotension/sphincter disturbances/erectile dysfunction)



  • Ataxia



  • There are two types: Parkinsonian and cerebellar


Accumulation of alpha-synuclein in glial cells


  1. L-DOPA typically does not work. (droxidopa/fludrocortisone)



  2. For systolic blood pressure: increase salt intake/compression stockings



  3. For bladder dysfunction: anticholinergics (oxybutynin/tolterodine)


Prognosis: average survival 6 y


Corticobasal degeneration




  1. Asymmetrical 5



  2. Alien hand syndrome



  3. Apraxia/aphasia

Involves cerebral cortex and basal ganglia

Tauopathy


  1. Poor response to L-DOPA



  2. Prognosis: death within 8 y

Note: Parkinson plus syndromes: progressive supranuclear palsy, multiple system atrophy, corticobasal degeneration.



12.4 Side Effects of Antipsychotics (Table 12.4)

























Disease

Presentation

Treatment

Tardivedyskinesia




  • Stereotyped movements:




    • Face and tongue



    • Lip smacking



    • Extremities: chorea



  • Caused by postsynaptic dopamine hypersensitivity induced by medication


  1. Stop antipsychotics



  2. Valbenazine (reduces the available dopamine in synapses)



  3. Benzodiazepines (clonazepam): tolerance is progressively developed



  4. Symptoms may start after first dose and may be irreversible even with treatment


Drug-induced Parkinsonism




  1. History of antipsychotics use (but may also be caused by antiemetics, antiepileptics, calcium-channel blockers) 6



  2. Parkinson-like symptoms (classically symmetric but not always)


  1. Reduce dose or stop the responsible drug



  2. Anticholinergics in the young



  3. Amantadine in the elderly

Note: Antipsychotics are dopamine antagonists as is metoclopramide (antiemetic). Risk is less with atypical antipsychotics (olanzapine) than typical (haloperidol).



12.5 Various Movement Disorders (Table 12.5)






















Disease

Presentation

Treatment

Essential tremor or familial tremor or idiopathic tremor 7




  • The most common movement disorder



  • Tremor ONLY with movement (usually action or postural)



  • Usually upper extremities/head/neck and oropharynx



  • Present only when awake




  1. Beta-blockers (propranolol, nadolol, timolol)



  2. Antiepileptics (topiramate, gabapentin, levetiracetam)/benzodiazepines, alcohol



  3. Avoid stress/caffeine



  4. Deep brain stimulation (ventral intermediate nucleus thalamus [VIM])


Dystonia




  • Slow sustained repetitive posture



  • Several forms (generalized, focal, multifocal, segmental with involvement of adjacent body parts, hemidystonia)



  • Cervical dystonia (spasmodic torticollis) and blepharospasm are the most common forms of focal dystonia


  1. Botulinum injection 8 (in affected muscles) with subsequent relief for 3–6 mo; then repeat



  2. Medications: anticholinergics/benzodiazepines/carbidopa or levodopa



  3. Selective neurotomy (sternocleidomastoid denervation for cervical dystonia)



  4. Deep brain stimulation: globus pallidus for early/childhood-onset variant and generalized form



12.6 Dorsal Colum sfunction (Table 12.6)


































Disease

Presentation

Other

Treatment

B12 deficiency (subacute combined degeneration of spinal cord)


  • Affects dorsal column + corticospinal tract + peripheral nerves, causing significant ataxia along with upper and lower motor neuron weakness



  • Also causes:




    • megaloblastic anemia



    • gastrointestinal symptoms



    • dementia



    • depression

High levels of methylmalonic acid (MMA) → damages myelin

B12 injections or oral administration


Friedreich’s ataxia




  • Affects dorsal column > cerebellar tract > corticospinal tract leading to:




    • ataxia



    • nystagmus



    • speech disturbance



    • minimal weakness



  • Associated with scoliosis, heart disease, diabetes

Autosomal recessive (expansion of GAA triplet reduces expression of mitochondrial protein frataxin) 9




  1. No truly effective treatment



  2. Speech therapy/physical therapy



  3. Treat the associated symptoms and diseases


Tabes dorsalis or syphilitic myelopathy




  • Dorsal column dysfunction (typical gait) + peripheral nerves



  • Weakness/paresthesias (often painful)/degeneration of the joints



  • Argyll Robertson pupil and visual disturbances



  • Personality changes/dementia/deafness/Loss of bladder control


  • The clinical manifestations may be delayed for many years.



  • There is demyelination caused by untreated Treponema pallidum infection (tertiary syphilis)


  1. IV penicillin



  2. Treat the pain (opiates and carbamazepine)



  3. Physical therapy

Note: Dorsal column: proprioception, vibration, discriminative touch.



12.7 Dementia (Table 12.7)




















































Disease

Presentation

Diagnostics

Other

Treatment

Wernicke’s encephalopathy




  • Acute dementia



  • Horizontal gaze palsy



  • Ataxia

MRI fluid-attenuated inversion recovery (FLAIR): signal is increased in:




  • Mammillary bodies



  • Dorsomedial thalamus



  • Tectal plate



  • Periaqueductal area in proximity of the 3rd ventricle

Deficiency of thiamine (vitamin B1) 10 as in:




  • chronic alcoholism



  • malnutrition



  • chemotherapy

100-mg thiamine (B1) IV + daily oral administration


Korsakoff’s syndrome




  • Chronic dementia



  • Amnesia



  • Confabulation 11



Creutzfeldt–Jacob disease (CJD)




  • Dementia



  • Myoclonus


  1. EEG: periodic spikes (periodic sharp wave complexes [PSWC])



  2. Lumbar puncture: normal or maybe increased protein. 14–3-3 protein has highest sensitivity and specificity for CJD



  3. MRI (FLAIR and diffusion weighted imaging [DWI]): abnormalities in cerebral cortex/striatum/thalamus




  • Treatment: NONE



  • Prognosis: death in less than 1 y


Alzheimer’s disease


The mostcommon cause of dementia

MRI: temporal and parietal atrophy

Neurofibrillary tangle (abnormally phosphorylated tau protein; may also be present in other diseases) + senile plaques (β-amyloid)


  1. Cholinesterase inhibitors/memantine (for cognitive symptoms)



  2. Selective serotonin reuptake inhibitors (for depression)



  3. Atypical antipsychotics (for agitation). CONCERNS: use of these medications may increase risk of mortality, cerebrovascular events, cardiovascular and metabolic complications, infections, falls



  4. Do not use benzodiazepines


Prognosis: death in 5 y: 70%


Pick’s disease




  • Dementia



  • Changes in behavior



  • Progressive nonfluent aphasia

MRI: frontal+ temporal atrophy

Tau proteins in neurons (silver staining: Pick’s bodies)

There is no therapy


Lewy body disease




  • Second most common cause of dementia 11



  • Sleep disturbance



  • May include Parkinsonian symptoms

MRI: temporal+ parietal + occipital atrophy

Lewy bodies: alpha-synuclein protein in neurons


  1. Cholinesterase inhibitors (for cognitive symptoms)



  2. Levodopa (in case of significant Parkinsonian symptoms)



  3. Melatonin and/or clonazepam for sleep disorders



  4. Use atypical antipsychotics if absolutely necessary. Avoid the typical ones



12.8 Multiple Sclerosis and Other Demyelinating Disorders (Table 12.8)










































Disease

Presentation

Diagnostics

Other

Treatment

Multiple sclerosis




  • Optic neuritis/sensory m otor symptoms/internuclear ophthalmoplegia



  • Two attacks in different places and different times



  • Females > males.



  • Three clinical types:




    • e. Relapsing remitting




      • Primary progressive



      • Secondary progressive (initially relapsing remitting)



  • Clinical signs




    • Uhthoff’s sign


      (symptoms worsen when temperature is higher)



    • Lhermitte’s sign


      (sense of current along the spine when bending the neck)


  1. MRI: white matter lesions:




    • Acute lesion is enhancing



    • Chronic lesion is a black hole in T2



    • Spares basal ganglia and thalamus



  2. CSF: increased protein + oligoclonal bands

Prevalence increases with distance from equator


  1. Acute phase:




    1. Steroids



    2. Plasmapheresis (if no response to steroids)



    3. IV immunoglobulins (if contraindication to steroids or plasmapheresis)



  2. Preventative:




    1. Interferon beta (may produce flulike symptoms and liver dysfunction)



    2. Daclizumab/ocrelizumab (for relapsing–remitting and primary progressive type)



    3. Mitoxantrone (for secondary progressive type)


Devic’s disease or neuromyelitis optica (NMO)




  • Acute bilateral painful decrease of vision (optic neuritis)



  • Spinal injury symptoms (myelitis)



  • Females > males



  • Monophasic or recurrent

Antibodies against astrocyte’s aquaporin-4 protein may be present (NMO-immunoglobulin G [IgG] test) 12


Neurologic sequelae tend to be more severe and permanent than multiple sclerosis

Similar to acute multiple sclerosis:




  1. IV steroids



  2. Plasmapheresis


Balo’s concentric sclerosis




  • Headache



  • Impaired cognition



  • Seizures

MRI: T2 sequence presents concentric layers of demyelination 13





  • Treatment: similar to acute multiple sclerosis



  • Prognosis: generally fatal


ADEM (acute disseminated/demyelinating encephalomyelitis)




  • Presents 2 wk after infection or vaccination (usually against rabies)



  • Monophasic deterioration 14 with variable symptoms (among which are fever, seizures, confusion)



  • Usually children


  1. MRI: lesions all over brain including basal ganglia and thalami



  2. CSF: increased protein and lymphocytes




  1. High-dose steroids



  2. Plasmapheresis



  3. IV IgG


Prognosis: mortality of 20%



12.9 Vasculitis (Tabe 12.9)




























































Disease

Presentation

Diagnostics

Other

Treatment


Arteries involved

Symptoms




Wegener’s granulomatosis or granulomatosis with polyangiitis


Affects small and medium vessels


  • Head: eyes, ears, sinuses, nasal or oral inflammation)/saddle nose deformity because of collapse of inflamed septum)



  • Kidneys: glomerulonephritis



  • Respiratory: hemoptysis due to lung lesion



  • Skin: palpable purpura



  • Nervous system: cranial and peripheral neuropathy


  1. Increased erythrocyte sedimentation rate (ESR)/C-reactive protein (CRP; in active disease)



  2. ANCA (antineutrophil cytoplasmic antibodies) 15



  3. CT: chest, sinuses



  4. Biopsy (renal and lung are most specific)

Autoimmune


  1. Steroids



  2. Cyclophosphamide


Behcet’s disease


Affects vessels of all sizes


  • Ocular (anterior or posterior uveitis: can lead to blindness)



  • Genital (ulcers)



  • Oral (aphthous ulcers)



  • Neurological (white matter) lesions may be present (even meningitis)


  1. Oral ulcerations are the most pathognomonic



  2. Possibly positive pathergy test (not specific)

Association with HLA-B51: risk factor


  1. Steroids



  2. Immunosuppressants



  3. Colchicine for mucosal involvement


Takayasu’s arteritis




  • Affects large and medium size vessels (aorta and its major branches typically)



  • Carotid and vertebral arteries


  • Systemic arteritis



  • Pulseless disease (absent or weak pulse usually in upper extremities because of aorta involvement)


  1. Increased ESR/CRP



  2. Angiography/MRA/CTA (several stenotic areas)



  3. Biopsy is not needed




  1. Steroids



  2. Endovascular treatment of aneurysms or stenosis)


Polyarteritis nodosa or Kussmaul–Maier disease




  1. Affects small and medium-sized arteries



  2. Usually spares pulmonary arteries 16



  3. Possibly small aneurysms like “beads of a rosary”




  • A multisystem disease that can affect almost any organ and even lead to polyvisceral failure.



  • Frequently testicular pain


  1. Increased ESR/CRP



  2. Hepatitis B surface antigen or antibody



  3. EMG (peripheral neuropathy/mononeuritis multiplex is common and confirming it helps the diagnosis)



  4. Angiography is not pathognomonic (aneurysms/stenoses of medium-sized vessels)



  5. Biopsy (nerves with pathological NCV/muscle/skin)

Association


with viral viral hepatitis (typically B and chronic) 16




  1. Steroids



  2. Cyclophosphamide, if no response to steroids but not in viral hepatitis-related disease



  3. Antiviral medication when indicated


Giant cell arteritis or temporal arteritis


Affects the cranial branches (mostly external carotid) of the arteries of the aortic arch


  • Headache



  • Eye pain/visual symptoms. Can cause blindness



  • Tenderness over temporal artery/jaw pain after chewing



  • Aortic aneurysm (thoracic) or dissection



  • Stroke


  1. Increased ESR/CRP



  2. Biopsy (superficial temporal artery)

Often associated with polymyalgia rheumatica

Steroids (start immediately to prevent vision issues, even before biopsy when necessary, in case of strong suspicion)

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May 11, 2020 | Posted by in NEUROSURGERY | Comments Off on 12 Neurology for Neurosurgeons

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