Parkinsonism

By Marcello Cherchi, MD PhD

For patients

The term “parkinsonism” refers to a group of problems with movement, including (1) slowness of movement, (2) a specific type of tremor, (3) stiffness in the limbs, and (4) unsteadiness. Many diseases can cause one or more of these symptoms. The most common is actual Parkinson’s disease, which is often treated with medications. Aside from actual Parkinson’s disease, there are several other diseases that can exhibit one or more parkinsonian features. In some cases it is difficult to tell these diseases apart, but the value of separating them from one another is that their treatments may be different. If your general doctor is uncertain which disease is causing parkinsonism, then referral to a specialist is sensible. The medical subspecialty of movement disorders focuses on diagnosing and treating parkinsonian disorders.

For clinicians

Overview

Distinguishing among the various parkinsonian disorder can be difficult, especially in the early stages of the diseases.  When an otoneurologist is consulted to help make this distinction, the relevant expertise is careful instrumented examination of eye movements with videonystagmography and, if possible, with rotatory chair testing.  Other otovestibular tests (vestibular evoked myogenic potentials, video head impulse testing, computerized dynamic posturography) may also show abnormalities in parkinsonian disorders, but the main value of these additional tests is to exclude competing diagnoses.  For example, identification of unilateral or bilateral vestibular weakness may provide a vestibular therapist a narrower therapeutic target.

Introduction

The term “parkinsonism” refers to a constellation of physical examination findings including bradykinesia (paucity of movement), resting tremor, cogwheel rigidity and postural instability. Multiple diseases can present with some subset of these findings.

Idiopathic Parkinson’s disease (IPD) was the first to be recognized, and is the archetype of parkinsonism, usually including most or all of the clinical features described earlier. This was first described by Dr. James Parkinson in, “An essay on the shaking palsy,” published in 1817. It is unique among parkinsonian disorders in that most patients exhibit a favorable response to levodopa.

All other types of parkinsonism tend to differ in one or more features from idiopathic Parkinson’s disease.

• Drug-related parkinsonism. Dopamine antagonists (such as some antipsychotic agents and several anti-emetic agents) have the potential to induce parkinsonism. Withdrawal of the offending drug may prevent further progression; in some cases the symptoms may improve.
• Toxin-related parkinsonism. Etiologies include carbon monoxide, manganese, MPTP, organic solvents, carbon disulfide.
• Vascular parkinsonism. This refers to infarctions in the basal ganglia. This can exhibit many of the features of IPD. It does not respond to dopamine.
• Neurodegenerative etiologies:
  • Progressive supranuclear palsy (PSP), previously eponymously designated Steele-Richardson-Olszewsky dynrome. It includes some parkinsonian features (bradykinesia, sometimes rigidity, and postural instability) but lacks others (tremor). Additional features include prominent and early falls; dysphagia; rigidity of the neck; and supranuclear palsy of vertical (more than horizontal) eye movements.
  • Corticobasal ganglionic degeneration (CBGD), sometimes also referred to as just “corticobasal degeneration.” This disorder usually has very asymmetrical motor findings (sometimes affecting just one limb) that may include akinesia, dystonia, rigidity and myoclonus, as well as the unusual features of ideomotor apraxia and alien limb phenomenon. There are usually accompanying cognitive deficits, such as executive dysfunction, aphasia, apraxia, visuospatial dysfunction and behavioral changes.
  • Lewy body disease, sometimes also referred to as “dementia with Lewy bodies.” Aside from parkinsonism, the other features of Lewy body disease include dementia with visual hallucinations, fluctuating cognition and REM sleep behavior disorder.
  • Bilateral striopallidodentate calcinosis, also eponymously designated Fahr disease. The sporadically occurring form is called idiopathic basal ganglia calcification (IBGC). It can also occur in a familial pattern, usually in an autosomal dominant fashion, in which case it is called primary familial brain calcification (PFBC). Clinical features are variable; besides parkinsonism these may include chorea, dystonia, ataxia and cognitive impairment.
  • Multiple systems atrophy (MSA) is an umbrella term for the following three neurodegenerative parkinsonian syndromes:
    • Olivopontocerebellar atrophy (OPCA), sometimes known as “MSA‑C,” meaning “MSA with prominent cerebellar features.”
    • Striatonigral degeneration, sometimes referred to as “MSA‑P,” meaning “MSA with predominant parkinsonian features.”
    • Shy-Drager syndrome, sometimes referred to as “MSA‑A,” meaning, “MSA with predominant autonomic features.”

Because these diseases often share parkinsonian features, they can be difficult to distinguish from one another, particularly early in the course of the disease. If there is uncertainty about the diagnosis, it is medically sensible to refer a patient to a movement disorders specialist.

Occasionally an otoneurologist may be called upon to help make this distinction because some of these diseases are more likely to have specific eye movement abnormalities. For example, progressive supranuclear palsy (PSP) characteristically has square wave jerks, supranuclear gaze palsy (with preserved reflex vestibulo-ocular reflex eye movements), slowing of vertical (more than horizontal) saccades, and “hang-up” at end-trajectory on optokinetic testing. These ocular motor findings may emerge gradually on serial otovestibular testing, and if they do, then a diagnosis of PSP is significantly more likely.