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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
 

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