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  • Common neurodegenerative disease of the CNS characterized by loss of dopaminergic input in the basal ganglia
  • Cause:
    • Generally considered idiopathic with some evidence of genetic and environmental components
    • Decreased incidence with exposure to cigarette smoking and increased with exposure to pesticides
  • Prevalence and incidence:
    • Affects 1 million people in the United States with approximately 50,000 new cases reported annually
    • Average age of onset is 60
  • Main signs:
    • Resting tremor
    • Rigidity
    • Bradykinesia
    • Festinating gait
    • Postural instability
  • Other signs:
    • Autonomic dysfunction (orthostatic hypotension, GERD, sialorrhea, cramps)
    • Pharyngolaryngeal involvement with aspiration (most common cause of death)
    • Respiratory involvement (chest rigidity, mixed obstructive–restrictive syndrome, decreased response to hypoxemia)
    • Dementia
    • Depression
    • Oculogyric crises
  • Treatment:
    • Goal of treatment: decrease cholinergic activity through anticholinergics or dopamine agonists
    • Levodopa:
      • Levodopa absorbed in proximal small bowel
      • Converted to dopamine by dopa decarboxylase
      • Five to 10% levodopa crosses blood–brain barrier; remainder converted to dopamine peripherally
      • Side effects are N/V, vasoconstriction, hypovolemia, hypotension, decreased myocardial NE stores
      • Levodopa supplementation leads to decreased endogenous production of dopamine
      • Peripheral decarboxylase inhibitor (carbidopa) in combination with levodopa (Sinemet®) decreases peripheral levodopa metabolism which decreases dopamine side effects
      • Entacapone, a COMT inhibitor, used alone (Comtan®) or in combination with carbidopa and levodopa (Stalevo®) to decrease peripheral metabolism of levodopa
      • Amantadine (Symadine®) releases Dopa in the striatum
    • Dopamine agonists:
      • Bind to postsynaptic receptors in the brain
      • Preferred in younger patients since they delay motor complications
      • Side effects include somnolence, insomnia, nausea, hallucinations, and cardiac valvular fibrosis with pergolide (Permax®) and cabergoline (Dostinex®, Cabaser®)
      • Other dopamine agonists include bromocriptine (Parlodel®), pramipexole (Mirapex®), and ropinirole (Requip®)
      • Apomorphine (Apokyn®), another agonist, is the only injectable medication (SQ only, not IV)
    • MAO-B inhibitors:
      • Increase peripheral bioavailability of levodopa. Selegiline (Eldepryl®, Emsam®, Zelapar®) and rasagiline (Azilect®) commonly used
    • Deep brain stimulation (DBS):
      • Used when drug therapy inadequate
      • Pacemaker implanted in brain to stimulate the subthalamic nucleus in the basal ganglia (see chapter 102, Awake craniotomy)

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  • Neuro evaluation preoperatively can be useful to establish baseline cognitive ability and to assist in perioperative management
  • Parkinson disease medications and glycopyrrolate (Robinul®) (to decrease sialorrhea and vagal tone) should be administered preoperatively
  • Levodopa half-life short (1–3 hours) and no IV form
  • May consider levodopa via OGT for lengthy non-GI surgery
  • Aspiration and laryngospasm are a significant concern secondary to GERD, sialorrhea, and dysfunction of upper airway musculature
  • Phenothiazines, droperidol, and metoclopramide (Reglan®) are contraindicated as antidopaminergic effect exacerbates extrapyramidal symptoms

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  • Regional versus general:
    • Regional anesthesia may be preferred
    • Hypotension secondary to autonomic dysfunction and vasodilatory effect of dopamine agonists is a major concern
    • Regional allows decreased perioperative opioids in patients with increased likelihood (8-fold) of postoperative hallucinations and confusion
  • General anesthesia:
    • Intubation may be difficult due to skeletal muscle rigidity
    • In ...

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