ABSTRACT
Sodium oxybate is currently approved in the United States exclusively for the treatment of cataplexy in narcoleptic patients. In a prior article published in this journal, we reported a patient with severe posthypoxic myoclonus whose myoclonus improved with ethanol and also with treatment with sodium oxybate. We extend this preliminary observation to five other patients with ethanol-responsive movement disorders in an open-label, dose-titration, add-on, 8-week trial. All five patients (one with severe alcohol-responsive posthypoxic myoclonus, two with epsilon-sarcoglycan-linked myoclonus-dystonia, and two with essential tremor) experienced improvement from baseline of 50% or greater as measured by blinded videotape review. Tolerability was satisfactory, with dose-dependent sedation as the most common side effect. Further studies of this drug in hyperkinetic movement disorders are warranted.
Subject(s)
Adjuvants, Anesthesia/therapeutic use , Central Nervous System Depressants/therapeutic use , Dystonia/drug therapy , Essential Tremor/drug therapy , Ethanol/therapeutic use , Myoclonus/drug therapy , Sodium Oxybate/therapeutic use , Adjuvants, Anesthesia/adverse effects , Adult , Aged , Central Nervous System Depressants/adverse effects , Drug Administration Schedule , Drug Therapy, Combination , Dystonia/diagnosis , Essential Tremor/diagnosis , Ethanol/adverse effects , Female , Humans , Male , Myoclonus/diagnosis , Pilot Projects , Severity of Illness Index , Sodium Oxybate/adverse effects , Treatment OutcomeABSTRACT
We conducted an open-label, dose-finding, blinded-rating trial of gamma-hydroxybutyric acid (Xyrem) in a single patient with severe alcohol-responsive posthypoxic myoclonus refractory to treatment with standard antimyoclonic agents. Xyrem was given in divided doses during the day and was well tolerated. Intensity of myoclonus was measured using the Unified Myoclonus Rating Scale, and blinded videotape review demonstrated complete resolution of myoclonus at rest and stimulus-sensitive myoclonus. Action myoclonus and functional performance also improved in ways that were practically meaningful, allowing her to feed herself, to accomplish daily hygiene tasks, and to walk with assistance. The possible mechanisms of action and potential uses of this agent in other alcohol-responsive movement disorders are discussed.
