Parkinson's disease

Background

• Extrapyramidal movement disorder associated with reduced dopaminergic receptors in substantia nigra

Clinical Features

• TRAP mnemonic:
  • Tremor (resting)
    • Initially is unilateral tremor of upper extremity, esp finger and thumb ("pill rolling")
    • Dissipates when intentional movement is performed
  • Rigidity (cogwheel)
    • Elicited by causing passive movement of limb through full range of motion
  • Akinesia
    • Slowness of voluntary movement
  • Posture/equilibrium impairment
    • Impaired ability to turn or change direction while walking

Differential Diagnosis

Dementia

• Degenerative
  • Alzheimer's disease
  • Huntington's disease
  • Parkinson's disease
• Vascular
  • Multiple infarcts
  • Hypoperfusion (MI, profound hypotension)
  • Subdural hematoma
  • SAH
• Infectious
  • Meningitis (sequelae of bacterial, fungal, or tubercular)
  • Neurosyphilis
  • Viral encephalitis (HSV, HIV), Creutzfeldt-Jakob disease
• Inflammatory
  • SLE
  • Demyelinating disease (e.g. multiple sclerosis)
• Neoplastic
  • Primary brain tumor / metastatic disease
  • Carcinomatous meningitis
  • Paraneoplastic syndromes
• Traumatic
  • Traumatic brain injury
  • Subdural hematoma
• Toxic
  • ETOH
  • Meds (anticholinergics, polypharmacy)
• Metabolic
  • B12 deficiency or folate deficiency
  • Thyroid Disease
  • Uremia
• Psychiatric
  • Depression (pseudodementia)
• Hydrocephalic
  • Normal pressure hydrocephalus (communicating hydrocephalus)
  • Noncommunicating hydrocephalus

Treatment

• Dopamine agonists
  • Levodopa  +Carbidopa (peripheral decarboxylase inhibitor) = gold standard
  • pramipexole (Mirapex)
    ropinirole (Requip)
• Anticholenergics
  • Benztropine
• Monoamine oxidase inhibitor - blocks DA reuptake
  • selegiline (Eldepryl)
  • rasagiline (Azilect)