Alerts and Notices
SynopsisParkinson disease is a neurodegenerative disorder caused by loss of dopaminergic cells. Average age of onset is 60 years, although it can less commonly affect individuals younger than 50 (early- or young-onset Parkinson disease). Cardinal symptoms include rest tremor, rigidity, bradykinesia, and postural and gait instability. Symptoms often start unilaterally but typically progress to bilateral involvement. Foot cramps are a common early symptom. Other common signs and symptoms include anosmia, constipation, rapid-eye-movement sleep behavior disorder (RBD), micrographia, decreased finger dexterity, reduced arm swing, masked facies, hypophonia, drooling, dysphagia, cognitive impairment, depression, anxiety, weight loss, and autonomic dysfunction. "Non-motor" symptoms may also include psychosis (eg, visual hallucinations, delusions).
The disease is progressive. Speed of progression is variable among patients, although it is generally slow (years), such that significant changes over less than a year's time should prompt consideration of other diagnoses. Five to ten percent of cases have a genetic propensity, often related to autosomal recessive mutations in the Parkin gene.
Several environmental factors are linked to Parkinson disease including certain pesticides, drinking well water, and exposure to industrial solvents like trichloroethylene, which are widely used in degreasing and dry cleaning.
Related topics: parkinsonism, dementia
G20 – Parkinson's disease
49049000 – Parkinson's disease
Differential Diagnosis & Pitfalls
- Drug-induced parkinsonism
- Essential tremor – tremor typically worse with action and sustained posture
- Multiple system atrophy – look for prominent autonomic symptoms (eg, light-headedness when standing, sexual dysfunction, urinary urgency) early in the course
- Progressive supranuclear palsy – early falls and eye movement abnormalities
- Corticobasal ganglionic degeneration – unilateral dystonia or other cortical sign, rigidity, parkinsonism
- Dementia with Lewy bodies – dementia early in the course of disease; fluctuations in cognition or alertness over hours
- Vascular parkinsonism – affects mostly legs and gait
- Frontotemporal dementia
- Alzheimer disease
- Huntington disease
- Wilson disease
- Neurodegeneration with brain iron accumulation
- Normal pressure hydrocephalus
- Manganese, mercury, cyanide toxicity
- Carbon monoxide poisoning – likely monophasic
- Traumatic brain injury – likely monophasic and not progressive