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For a clinical review of the topic in Current Diagnosis & Treatment, 3e please go to Chapter 15: Movement Disorders.


In most realms of neurologic disease, localization is the first step toward differential diagnosis. In assessing movement disorders, however, the first step is to accurately characterize the type of abnormal movement(s) present, each of which has its own differential diagnosis. The differential diagnosis for movement disorders can generally be divided into the following four broad categories, with each movement disorder having particular etiologies in each category (Table 23–1):

TABLE 23–1Characteristics & Common Differential Diagnoses of Movement Disorders.

  • Primary neurologic diseases

  • Structural neurologic lesions

  • Systemic conditions

  • Medication/drug-induced

Any category of movement disorder can also have a functional etiology, meaning it cannot be explained by a known underlying neurologic disease (previously called “psychogenic” movement disorders; see “Functional Movement Disorders”).

Movement disorders are broadly classified as either hyperkinetic (increased movement: tremor, chorea, myoclonus, dystonia, tics) or hypokinetic (decreased movement: bradykinesia as is seen in parkinsonism). In general, a unilateral movement disorder suggests a structural lesion, whereas a bilateral movement disorder suggests a systemic, toxic, or degenerative cause, but there are many exceptions: hyperglycemic chorea is often unilateral; Parkinson’s disease and corticobasal syndrome are often unilateral at onset and remain asymmetric throughout the disease course.


Tremor refers to rhythmic oscillation (i.e., shaking) of one or more parts of the body (Table 23–2). ...

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