Snapshot A 65-year-old man present with a tremor in his right hand. The tremor is maximal at rest, diminishes during movement, and is absent during sleep. Family members report changes in facial expression. Introduction An idiopathic, slowly progressive, degenerative CNS disorder Parkinson's disease is the fourth most common neurodegenerative disease of the elderly Mean onset at aget 57 Primary Parkinson's Disease pigmented neurons of the substantia nigra, locus ceruleus, and other brain stem dopaminergic cell groups are lost loss of substantia nigra neurons, which project to the caudate nucleus and putamen, results in depletion of the neurotransmitter dopamine in these areas Secondary Parkinsonism loss or interference with the action of dopamine in the basal ganglia due to idiopathic degenerative diseases, drugs, or exogenous toxins most common cause is antipsychotic drugs (e.g., reserpine, blocks dopamine receptors) It may begin in childhood or adolescence (juvenile parkinsonism) Multiple System Atrophy A distinct disease from Parkinson's; however shares many common symptoms Characterized by autonomic dysfunction, Parkinsonism symptoms, cerebellar ataxia Parkinsonism symptoms show minimal or no response to levodopa therapy (differentiating factor from Parkinson's disease) Most common in men in late 50s to early 60s Histopathologic examination shows abundant glial cytoplasmic inclusions in CNS tissue No cure available, supportive treatment; disease progresses rapidly with death often occuring 8-12 years after symptom onset Presentation Symptoms 50 to 80% of patients, the disease begins insidiously with a resting pill-rolling tremor movement becomes slow (bradykinesia), decreased (hypokinesia), and difficult to initiate (akinesia) cog wheel Rigidity classic shuffling gait mask like facies dementia due to loss of dopaminergic neurons in substantia nigra speech becomes hypophonic, with a characteristic monotonous, stuttering dysarthria Evaluation Diagnosis is clinical Rule out other causes benign essential tremor Differential Severe depression, intoxication, phenothiazine side effects, rare neurodegenerative disease. Treatment Pharmacologic Sinemet (levodopa, carbidopa) best for bradykinesia but may cause dizziness, headache, and hallucinations Bromocriptine and pergolide directly activate dopamine receptors in the basal ganglia Anticholinergics (benztropine/trihexyphenidyl) for tremor Amantadine effective in increasing dopamine in mild disease Selegiline inhibits one of the two major enzymes that breaks down dopamine in the brain Surgical pallidotomy for refractory cases Prognosis, Prevention, and Complications Usually progresses despite treatment