RT Book, Section A1 Tinklepaugh, Mark S. A2 Atchabahian, Arthur A2 Gupta, Ruchir SR Print(0) ID 57260694 T1 Chapter 29. Parkinson Disease T2 The Anesthesia Guide YR 2013 FD 2013 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-176049-2 LK accessanesthesiology.mhmedical.com/content.aspx?aid=57260694 RD 2024/10/07 AB Common neurodegenerative disease of the CNS characterized by loss of dopaminergic input in the basal gangliaCause:Generally considered idiopathic with some evidence of genetic and environmental componentsDecreased incidence with exposure to cigarette smoking and increased with exposure to pesticidesPrevalence and incidence:Affects 1 million people in the United States with approximately 50,000 new cases reported annuallyAverage age of onset is 60Main signs:Resting tremorRigidityBradykinesiaFestinating gaitPostural instabilityOther 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)DementiaDepressionOculogyric crisesTreatment:Goal of treatment: decrease cholinergic activity through anticholinergics or dopamine agonistsLevodopa:Levodopa absorbed in proximal small bowelConverted to dopamine by dopa decarboxylaseFive to 10% levodopa crosses blood–brain barrier; remainder converted to dopamine peripherallySide effects are N/V, vasoconstriction, hypovolemia, hypotension, decreased myocardial NE storesLevodopa supplementation leads to decreased endogenous production of dopaminePeripheral decarboxylase inhibitor (carbidopa) in combination with levodopa (Sinemet®) decreases peripheral levodopa metabolism which decreases dopamine side effectsEntacapone, a COMT inhibitor, used alone (Comtan®) or in combination with carbidopa and levodopa (Stalevo®) to decrease peripheral metabolism of levodopaAmantadine (Symadine®) releases Dopa in the striatumDopamine agonists:Bind to postsynaptic receptors in the brainPreferred in younger patients since they delay motor complicationsSide 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 usedDeep brain stimulation (DBS):Used when drug therapy inadequatePacemaker implanted in brain to stimulate the subthalamic nucleus in the basal ganglia (see chapter 102, Awake craniotomy)