[Palatal myoclonus associated with a decrease in 5-hydroxy-indole acetic acid in cerebrospinal fluid and responding to clonazepam].

A patient representing with palatal myoclonus was diagnosed as suffering from possible multiple sclerosis. A reduction of cerebrospinal 5-hydroxy-indole-acetic acid suggested a decreased central serotonergic turnover. A therapeutic trial with clonazepam, a serotonergic agonist, improved the myoclonus symptomatically. The possible involvement of serotonergic inhibitory systems in the expression of palatal myoclonus is discussed.