In the 2009 edition of "Anesthesia," Dr. Irene Iselin-Chaves explains how drugs used during anesthesia have been reported to temporarily induce symptoms of Parkinson's Disease in previously healthy patients and exacerbate symptoms in patients already diagnosed with the disease. According to Iselin-Chaves, symptoms may appear as soon as the drug is administered or only when the patient emerges from anesthesia. Compared to general anesthesia, use of spinal anesthesia appears to offer reduced risk of this complication.
Inhalational Anesthetics
Sevoflurane, an anesthetic gas used in general anesthesia, accounts for most cases of Parkinsonism linked to anesthetic agents. The local anesthetic agents used to induce spinal anesthesia remain in the spinal canal and do not affect the centers of the brain involved in Parkinson's Disease.
Sedatives
During spinal anesthesia, patients remain conscious, so anesthesiologists often add sedative medications to help them relax. Propofol is a popular, fast-acting, rapidly metabolized, intravenous sedative that has been reported to trigger symptoms of Parkinson's Disease in a few patients.
Opioids
Alfentanil and other opioids belong to a class of drugs known as analgesics. Analgesics treat pain by sending pleasure signals that cancel out pain signals. In some cases, anesthesiologists use them during spinal anesthesia to achieve pain control at a lower dose of local anesthetic and extend the duration of post-operative pain relief. As with sedatives, opioids have also been reported to trigger Parkinsonism.
Anti-Emetics
Anti-emetics such as metoclopramide have long been used to decrease the incidence of nausea and vomiting during the post-operative period. However, most anti-emetics also exert pronounced effects on the acetylcholine neurotransmitter system, which plays a key role in Parkinson's Disease. According to anesthesiologist Wayne Kleinman in the 2006 edition of "Clinical Anesthesiology," spinal anesthesia causes nausea and vomiting far less often than general anesthesia, however the use of narcotics for post-operative pain relief may cancel out this benefit.
Mechanism
All of the implicated drugs create an imbalance between two types of neurotransmitters, dopamine and acetylcholine, in the basal ganglia, which is the part of the brain that coordinates movement. In Parkinson's Disease, symptoms result from the death of cells that produce these neurotransmitters. For patients with Parkinson's Disease related to spinal anesthesia, symptoms usually last only as long as it takes for the drugs to wear off.
Treatment
Treatment for patients with Parkinson's Disease related to spinal anesthesia begins with discontinuation of the offending agent. Sometimes, the culprit can be identified on the basis of patient history. In other cases, it is revealed by the drug that successfully reverses it. For example, symptoms that resolve with the administration of the opioid antagonist, naloxone, point to opioids. Relief with the anticholinergic drugs benztropine or diphenhydramine suggests anti-emetics.
Prevention
Since symptoms of Parkinson's Disease inevitably recur with repeat administration of the offending agent, it's important for patients to talk to their anesthesiologist about what happened and how to prevent it in the future. Patients often have difficulty recalling information during the post-operative period, so it helps to have a family member or trusted friend take notes.
References
- "Anesthesia;" Naloxone-Responsive Acute Dystonia and Parkinsonism Following General Anaesthesia; A. Iselin-Chaves et al.; 2009
- "Clinical Anesthesiology, 4th edition;" G.E. Morgan et al. 2006
- "Anesthesia;" Dystonic Reaction Following Anesthesia; R.C. Sinclair et al.; 2004
