Parkinsonism

PARKINSONISM

The cardinal tetrad of parkinsonism includes tremor, rigidity, akinesia/bradykinesia, and postural instability.¹ The most common cause of parkinsonism is Parkinson’s disease (PD), which is discussed in Chapters 2 and 4. Other neurodegenerative causes of parkinsonism include progressive supranuclear palsy, dementia with Lewy bodies, multiple system atrophy, and corticobasal degeneration.

TREMORS

Tremors are the presenting symptom of PD in 40% to 70% of cases, and between 68% and 100% of patients with PD will have resting tremor at some point during the course of their illness.² However, 10% to 20% of patients with PD do not have tremor.

The tremor in PD is typically resting, although postural tremor and action tremor may be present.

The typical resting tremor in PD is 4 to 6 Hz in frequency and most prominent in the distal extremity (also called pill-rolling tremor because the tremor has a rotatory component).³

Reemergent tremor (with a latency of a few seconds before the tremor reemerges during postural holding) occurs in PD.⁴

Distraction may help “bring out” a resting tremor, especially if the patient is anxious (eg, if the patient is asked to count backward). Certain provocations, such as naming the months of the year backward, may exacerbate the tremor.

Tremor usually starts in one hand and arm, then progresses to the ipsilateral leg. It later spreads contralaterally.

Lips, chin, and jaw tremors are common in PD, but head tremors are rare in PD, although they are common in essential tremor.

Head tremor, seen as nodding (“yes–yes” tremor) or shaking (“no–no” tremor), is a feature of essential tremor rather than PD but can rarely occur in PD.⁵

Head tremor can also occur in patients with cervical dystonia.

Tremors are often the most unpredictable symptom to treat. About half of patients will notice a treatment response, with improvement in tremor, but tremor is seldom completely abolished.

Patients can be troubled by the persistence of tremor despite therapy, and they may report that the treatment is not working because tremor remains, even though bradykinesia has improved.

Table 3.1 lists the differences between PD tremor and essential tremor.⁶

Table 3.1
Comparison of Parkinson’s Disease Tremor and Essential Tremor

Characteristics	Parkinson’s Disease Tremor	Essential Tremor
Tremor	At rest ± reemergent tremor	Postural tremor
Frequency	4–6 Hz	5–12 Hz
Distribution	Asymmetric	Mostly symmetric
Body parts affected	Hands ± legs	Hands, head, voice
Writing	Small (micrographia)	Large and tremulous
Course	Progressive	Stable or slowly progressive
Family history	Uncommon (1%)	Common (>30%)
Extrapyramidal signs (bradykinesia, rigidity, and loss of postural reflex)	Present	Absent
Relieving factors	Levodopa, dopamine agonists, anticholinergics	Alcohol, propranolol, primidone, topiramate, gabapentin, clonazepam
Usual site for surgical treatment with deep brain stimulation	Subthalamic nucleus or globus pallidus interna	Ventral intermediate thalamus

Source: Adapted from Ref. 6: Bhidayasiri R. Differential diagnosis of common tremor syndromes. Postgrad Med J. 2005; 81:756–762.

RIGIDITY

Rigidity is an involuntary increase in muscle tone and can affect all muscle groups.

Typically, cogwheel rigidity, especially when associated with tremor;⁷ may result in flexed neck and trunk posture.

Rigidity is present throughout the range of movement. The term “lead pipe” rigidity can be used to describe movement that feels smooth. The term “cogwheel” rigidity is used when movement feels ratcheted. Although there may be a subjective coexisting tremor that gives a feeling of cogwheeling, true cogwheeling is a form of rigidity independent of tremor.

Rigidity is tested by passively moving the limb.

Mild rigidity may require “activation,” such as by asking the patient to open and close the contralateral hand, before it can be appreciated by the examiner.⁸

Patients describe rigidity as muscle stiffness or sometimes pain. Not uncommonly, patients with PD experiencing significant rigidity initially present to an orthopedist with a “frozen shoulder.”^{9, 10} Pain in PD may also be caused by dystonia.

BRADYKINESIA/AKINESIA

Bradykinesia is a slowness of initiating voluntary movement and sustaining repetitive movements, with progressive reduction in speed and amplitude.⁷

Hypokinesia is paucity of movement.

Patient symptoms and functional limitations that reflect bradykinesia and hypokinesia include the following:⁷

Loss of arm swing

Difficulty walking, with a tendency to drag a leg in early disease

Increasingly small handwriting (micrographia)

Difficulty with fine hand movements—manipulating buttons and zippers and cutting food

Difficulty turning in bed

Loss of facial expression, often described as a masklike face (hypomimia)

Hypophonia (reduced voice volume and modulation)

Bradykinesia causes significant disability affecting the quality of life of patients with PD and almost always responds to antiparkinsonian therapy.

POSTURAL INSTABILITY

Patients report poor balance, unsteadiness, and falls.¹¹

Postural instability is examined with the pull test.¹²

The examiner stands behind the patient and pulls back sharply on the patient’s shoulders (the feet should be slightly apart, unlike their position in a Romberg test).

Patients typically correct themselves easily in the early stages. They develop some retropulsion later on, in which they may take two to three steps back but can still correct themselves. Finally, in advanced stages, they may fall if unsupported.

GAIT DYSFUNCTION

Shuffling gait is usually seen in akinetic–rigid syndromes like PD.

It may be the initial complaint in patients with non–tremor-predominant PD (often termed the akinetic–rigid variant or postural instability–gait dysfunction variant of PD).

Other conditions that may present with a shuffling gait include multiple system atrophy (MSA), progressive supranuclear palsy (PSP), corticobasoganglionic degeneration (CBGD), dementia with Lewy bodies (DLB), normal-pressure hydrocephalus (NPH), some dementing processes, and frontal lobe syndromes, among others.

The patient with a characteristic shuffling gait adopts a stooped posture, with flexion of the neck and shoulders.

Steps are short. The trunk is flexed and rigid, and the knees tend to be flexed.

However, the patient with PSP often adopts a more erect truncal posture, whereas truncal flexion can be accentuated in MSA.

A cock gait has been described in parkinsonism resulting from manganese toxicity, with an exaggerated lumbar lordosis and leg movements resembling those of a cock walking. A magnetic gait is classically attributed to NPH and is described as slightly wide-based, unsteady, and associated with some difficulty lifting the foot, “as if a magnet underneath is preventing the normal heel–toe stride.” However, NPH can also present with a typical shuffling, parkinsonian gait, or the marche à petit pas (“walk with small steps”) seen in vascular parkinsonism.

The patient with PD (and also the patient with CBGD) usually has an asymmetric arm swing compared with patients who have other parkinsonian disorders.

Festination,¹³ defined as a tendency to increase velocity but with shorter steps, may also be seen in the shuffling patient and is a characteristic, but not specific, finding in PD.

The symptoms accompanying parkinsonism usually are the ones that give a clue to the diagnosis. For example:

When a shuffling gait is associated with urinary incontinence and cognitive impairment, NPH should be considered.¹⁴

When a shuffling gait is associated with early falls and vertical ophthalmoplegia, PSP should be considered.¹⁵

When cognitive impairment occurs early, DLB, CBGD, and PSP should be considered.

Prominent autonomic dysfunction suggests MSA.¹⁶

Likewise, marked disequilibrium early in the disease is more suggestive of PSP, DLB, or MSA.

Other gait abnormalities that may also present with shuffling are the following:

Isolated gait ignition failure.¹⁷ The patient often presents with difficulty initiating gait and frequent freezing during ambulation, aggravated by turning. The patient usually has normal postural responses but may have mild parkinsonian symptoms.

Frontal gait disorder.¹⁸> The patient gives the appearance of having the feet “glued” or “magnetized” to the floor. It is very difficult to initiate gait, and when gait is initiated, it may be shuffling in nature. Special maneuvers, like turning, may exacerbate the symptoms. This syndrome can result from extensive, bilateral ischemic white matter disease (atherosclerotic/vascular parkinsonism), hydrocephalus, or other frontal lobe disorders. It has also been called gait apraxia.

EXAMINATION OF THE PATIENT WITH SHUFFLING

Once a comprehensive history is obtained, a careful evaluation of gait should be performed (Table 3.2).¹⁹

Observe trunk posture while the patient is walking. The patient’s pace, stance, stride, initiation, and performance in special maneuvers (eg, turning) should be noted.

With the patient initially seated, ask him or her to stand up without pushing on the arm rests. Although failure to stand without assistance can result from proximal muscle weakness of the lower extremities (eg, a myopathic condition), the same problem is often appreciated in moderate and severe stages of parkinsonism.

Ask the patient to initiate walking. It should be an easy, free-flowing process.

Hesitation in starting gait is suggestive of an akinetic–rigid syndrome.

Once gait is initiated, stride, stance, and velocity should be noted.

Shuffling steps are suggestive of an akinetic–rigid syndrome, and the shuffling may range in severity from very short steps to complete inability to ambulate (“magnetic feet”).

A wide-based gait or difficulty in heel-to-toe walking suggests a concomitant cerebellar disorder such as olivopontocerebellar (OPCA) type of MSA or truncal ataxia.

The patient should be observed in special maneuvers, such as when asked to turn in a corner or suddenly change direction. This may cause the patient to “freeze” or may worsen the shuffling.

The examiner should pay attention to symptom asymmetry or the development of tremors, which are features suggestive of PD.

The postural reflexes should then be examined, and the clinician usually performs this examination by standing behind the patient and giving him or her a good tug on the shoulders.

Examine for rigidity, bradykinesia, and tremors.

Look for associated features, such as apraxia, ataxia, sensory abnormalities, aphasia, cognitive impairment, and hyperreflexia.

Table 3.2
Important Aspects of Gait Evaluation

Gait Aspect	Characteristics
Posture	Stooped versus upright
Stance	Narrow versus wide-based
Speed	Slow versus normal, with or without festination
Stride	Short, normal, or long
Gait initiation	Is there hesitation? Is it “magnetic”?
Freezing	Is there freezing during gait ignition or during turning?
Symptom asymmetry	Is the parkinsonism symmetric or asymmetric?
Heel–toe walking	Look for truncal ataxia, cerebellar features
Postural reflexes	Early versus late onset
Falls	Backward or forward, early versus late onset

DIFFERENTIAL DIAGNOSIS OF PATIENTS PRESENTING WITH PARKINSONISM

Patients presenting with parkinsonism as the main feature can be broadly classified as having primary parkinsonism, secondary parkinsonism, or a Parkinson-plus syndrome, as defined in Chapter 1 (Table 3.3).²⁰

Parkinson-Plus Syndromes

Dementia with Lewy bodies (DLB)^21–25

DLB is characterized by progressive dementia with prominent attention and visual defects fluctuation in cognition and attention, visual hallucinations, and parkinsonism.

It may be difficult to differentiate from PD dementia because patients with either condition can exhibit fluctuations in sensorium/alertness, frequent falls, hallucinations, and sensitivity to PD medications (Table 3.4).

Recurrent visual hallucinations and delusions (may be unrelated to medications).

Symmetric akinetic–rigid parkinsonism (bradykinesia and rigidity > tremor).

Gait abnormalities and falls occur early.

REM sleep behavior disorder is common.

There is a partial response to levodopa.

Dementia occurs before or within 1 year after onset of parkinsonism in DLB.

Table 3.3
Classification of Disorders With Parkinsonism as the Main Feature

Primary Parkinsonism	Parkinson-Plus Syndromes	Secondary Parkinsonism
Parkinson’s disease	Progressive supranuclear palsy (PSP)	Drugs
Juvenile parkinsonism	Multiple system atrophy (MSA)	Metabolic causes
	Corticobasal syndrome (CBS)	Toxins
	Dementia with Lewy bodies (DLB)	Trauma
	Parkinsonism–dementia–amyotrophic lateral sclerosis complex	Postencephalitic parkinsonism Prion disorders Brain tumor Vascular causes