Parkinson's disease

Background

Extrapyramidal movement disorder associated with reduced dopaminergic receptors in substantia nigra
Most common presentations to the ED^[1]:
- Infectious ~32%
- Trauma ~28%
- Cardiovascular ~15%
- Cerebrovascular ~12%
- GI ~7%
- Electrolyte abnormalities 6%

Tremor (resting)
- Initially is unilateral tremor of upper extremity, especially 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

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

Dopamine agonists
- Levodopa and Carbidopa (peripheral decarboxylase inhibitor) = gold standard
- pramipexole (Mirapex)
  ropinirole (Requip)
Anticholenergics
- Benztropine - caution in acute psychosis
Monoamine oxidase inhibitor - blocks DA reuptake
- Selegiline (Eldepryl)
- Rasagiline (Azilect)
Agents for psychotic symptoms, hallucinations
- Pimavanserin (Nuplazaid) - serotonin inverse agonist (not anti-dopamine), FDA approved in 2016^[2]
- Avoid antidopaminergic drugs if possible (expect worsening motor symptoms), but commonly used agents:
  - Olanzapine
  - Quetiapine
- Others:
  - Rivastigmine
  - Citalopram in depressed patients

↑ Guneysel O et al. Parkinson’s disease and the frequent reasons for emergency admission. Neuropsychiatr Dis Treat. 2008 Aug; 4(4): 711–714.
↑ FDA approves first drug to treat hallucinations and delusions associated with Parkinson’s disease. April 29, 2016. http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm498442.htm.