Parkinson's Disease

Parkinson's Disease is a topic covered in the Harrison's Manual of Medicine.

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Parkinsonism is a general term used to define a syndrome manifest as bradykinesia (slowness of voluntary movements) with rigidity and/or tremor; it has a wide differential diagnosis (Table 183-1). Parkinson’s disease (PD) is idiopathic parkinsonism without evidence of more widespread neurologic involvement. PD afflicts >1 million individuals in the United States. Mean age of onset is about 60 years; course progressive over 10–25 years. Tremor (“pill rolling” of hands) at rest (4–6 Hz). Presentation with tremor confined to one limb or one side of body is common. Other findings: rigidity (“cogwheeling”—increased ratchet-like resistance to passive limb movements), bradykinesia, fixed expressionless face (facial masking) with reduced frequency of blinking, hypophonic voice, drooling, impaired rapid alternating movements, micrographia (small handwriting), reduced arm swing, and flexed “stooped” posture with walking, shuffling gait, difficulty initiating or stopping walking, en-bloc turning (multiple small steps required to turn), retropulsion (tendency to fall backwards). Nonmotor aspects of PD include depression and anxiety, cognitive impairment, sleep disturbances, sensation of inner restlessness, loss of smell (anosmia), and disturbances of autonomic function. Normal muscular strength, deep tendon reflexes, and sensory examination. Diagnosis based on history and examination; neuroimaging, EEG, and CSF studies usually normal for age.

Parkinson’s DiseaseAtypical ParkinsonismSecondary ParkinsonismOther Neurodegenerative Disorders
GeneticMultiple-system atrophy (MSA)Drug-inducedWilson’s disease
SporadicCerebellar type (MSA-c)TumorHuntington’s disease

Dementia with Lewy bodies

Parkinson type (MSA-p)

Progressive supranuclear palsy

Corticobasal ganglionic degeneration

Frontotemporal dementia



Normal-pressure hydrocephalus


Liver failure

Toxins (e.g., carbon monoxide, manganese, MPTP, cyanide, hexane, methanol, carbon disulfide)

Neurodegeneration with brain iron accumulation

SCA 3 (spinocerebellar ataxia)

Fragile X–associated ataxia-tremor-parkinsonism

Prion disease

Dystonia-parkinsonism (DYT3)

Alzheimer’s disease with parkinsonism

Abbreviations: MPTP, 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine.

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