Treatment of myoclonus with L-5-hydroxytryptophan and carbidopa: clinical, electrophysiological, and biochemical observations.
Six patients with myoclonus of varying cause were treated with L-5-hydroxytryptophan (L-5-HTP) and carbidopa. While spontaneous myoclonus decreased in three of the patients and action myoclonus in four, only two patients had marked functional improvement. Side effects included gastrointestinal and affective disturbances. L-5-HTP therapy caused a diminished frequency of paroxysmal discharges in the electroencephalograms of three patients which did not always correlate with clinical improvement. Lumbar cerebrospinal fluid 5-hydroxyindoleacetic acid (5-HIAA) concentration after probenecid was decreased in all patients prior to therapy, but this reduction did not predict treatment response. Urinary excretion patterns for 5-HTP, serotonin, and 5-HIAA during treatment were similar in responders and nonresponders. It is concluded that while some patients with myoclonus do benefit from L-5-HTP therapy, biochemical and electrophysiological tests are not useful predictors of treatment response, and the high incidence of side effects limits the usefulness of this therapy.
D006916:5-Hydroxytryptophan / Q000008:administration & dosage* / Q000009:adverse effects; D000293:Adolescent; D000328:Adult; D002230:Carbidopa / Q000008:administration & dosage* / Q000009:adverse effects; D002998:Clonazepam / Q000008:administration & dosage; D003967:Diarrhea / Q000139:chemically induced; D004359:Drug Therapy, Combination; D004569:Electroencephalography; D004576:Electromyography; D006801:Humans; D008875:Middle Aged; D009207:Myoclonus / Q000175:diagnosis / Q000188:drug therapy* / Q000378:metabolism; D009325:Nausea / Q000139:chemically induced; D010634:Phenobarbital / Q000008:administration & dosage; D012701:Serotonin / Q000378:metabolism
D012701:Serotonin; D002998:Clonazepam; D006916:5-Hydroxytryptophan; D002230:Carbidopa; D010634:Phenobarbital