Movement disorders are a cluster of motor disturbances arising from the dysfunction of basal ganglia and, in some cases, from other parts of the nervous system, for example, brainstem, cortex, spinal cord, cerebellum, and peripheral nervous system. Patients suffering from movement disorders have normal muscle strength and sensation, but their normal voluntary motor activities are influenced or impaired by the involuntary movement, alteration in muscle tone or posture, and loss of coordination or regulation—either facilitation or inhibition—of pyramidal motor activities as a result of malfunction. Movement disorders can be classified into the following categories based on their clinical manifestations: tremor, chorea and choreoathetosis, dystonia, myoclonus, tics, and ataxia. They demonstrate less movement, hypokinesia or akinesia, or excessive movement, hyperkinesia, or both (Table 43-1). The goal of this chapter is to provide clinical information regarding the diagnosis, management, and recent findings for the most commonly encountered movement disorders. Nonmotor features of movement disorders are also discussed in an effort to improve comprehensive care and patients' quality of life.
Table 43-1. Classification of Movement Disorders. |Favorite Table|Download (.pdf)
Table 43-1. Classification of Movement Disorders.
|Hypokinetic Disorders||Hyperkinetic Disorders|
|Secondary parkinsonism:||Tics (Tourette syndrome)|
|Drug-induced parkinsonism||Chorea (Huntington disease)|
|Normal pressure hydrocephalus (NPH)||Dystonia/athetosis|
|Other: infections, toxins, metabolic disorders||Ataxia|
|Parkinson-plus syndromes||Akathisia (almost always affects the legs)|
|MSA (Shy-Drager, OPCA, SND)||Restless leg syndrome|
At least two of the first three cardinal motor features, which are unilateral, and absence of a secondary cause:
- 4-6 Hz rest tremor.
- Muscular rigidity.
- Postural instability (late presentation).
Parkinson disease (PD) is the second most common progressive neurodegenerative disorder after Alzheimer disease but remains the only neurodegenerative disease for which symptoms can be effectively controlled medically. It affected about 340,000 individuals older than 50 years in the United States, according to the estimate of Dorsey et al (2005). In the United States, the prevalence of PD is estimated at 128 per 100,000 in individuals in their fifties, 550 per 100,000 in those in their sixties or seventies, and 958 per 100,000 in those older than 80 years. The number is expected to grow in the next 25 years, with the projected number being 610,000 in 2030 in the United States (Dorsey et al, 2007). The number of individuals with PD older than 50 years in Western Europe's five most and the world's 10 most populous nations was between 4.1 and 4.6 million in 2005 and will double to between 8.7 and 9.3 million by 2030 (Dorsey et al, 2007).
Numerous hypotheses, for example, environmental, genetic, inflammatory process, defects in ...