Buspirone in progressive myoclonus epilepsy

Buspirone-associated Movement Disorder: A Literature Review

Buspirone (BUS) belongs to the azapirone chemical class. The aim of this literature review is to evaluate the clinical epidemiological profile, pathological mechanisms, and management of BUS-associated movement disorders (MD). Relevant reports in six databases were identified and assessed by two reviewers without language restriction. A total of 25 reports containing 65 cases were assessed. The MD associated with BUS were: dyskinesia in 14 cases, 10 of akathisia, 8 of myoclonus, 6 of Parkinsonism, and 6 of dystonia. The cases not clearly defined were 7 tension, 14 incoordination, and the undefined number of dyskinesia, tics, and Parkinsonism. The mean age was 45.23 years (range: 15-74). The male was the predominant sex in 60.86% and the most common BUS-indication was anxiety disorder. The mean BUS-dose was 42.16 mg (range: 5-100). The time from the beginning of BUS administration to the MD onset was one month or less in 76%. The time from BUS withdrawal to complete recovery was within one month in 87.5%. The most common management was BUS withdrawal. In 16 patients the follow-up was reported: 14 had a full recovery, but in two (1 dyskinesia + 1 dystonia) the symptoms continued after the BUS withdrawal. MD associated with BUS were scarcely reported in the literature. Moreover, in the majority of cases, no clear description of the clinical profile, neurological examination, or the time data of the movement disorder onset and recovery were given.

Chloral hydrate for progressive myoclonus epilepsy: a new look at an old drug

This study demonstrates that chloral hydrate can be used to control daytime myoclonic exacerbations. It reports on four patients with progressive myoclonus epilepsy--three with Unverricht-Lündborg disease (EPM1) and one with progressive external ophthalmoplegia (PEO)--all of whom were taking more than one antiepileptic drug. Response to the liquid formulation was faster than response to the capsule and was preferred by the patients. The unusual feature was less than expected sedation or development of tolerance even at daily doses above 500 mg administered for years. Because chloral hydrate helped to improve quality of life, it should be made available to patients with progressive myoclonus epilepsy as adjunctive therapy. Recent evidence of interactions with various excitatory and inhibitory amino acid neurotransmitter-operated ion channels as a mechanism of action may provide insight into altered neurotransmission in progressive myoclonus epilepsy.

Antidyskinetic drug therapy for pediatric movement disorders

The pharmacologic armamentarium used to treat dyskinesias in childhood is increasing. Anticonvulsant drugs as a class are still some of the broadest-spectrum antidyskinetic agents, probably because the class includes so many differently acting drugs or because dyskinesias are manifestations of subcortical electrical events. This group is enhanced by recent developments in gamma-aminobutyric acid and glutamate receptor pharmacology, which promise new antidyskinetic drugs. Other drugs acting at receptors for monoamines (dopamine, norepinephrine, and serotonin), acetylcholine, opioids, or histamine may provide symptomatic improvement. Fewer pharmacotherapies address the underlying pathophysiology of movement disorders. Of these, drugs or biologicals for immunomodulation are the most developed, but the group also includes antioxidants, cofactors, metabolic inhibitors, and chelators. There is potential for drugs that block the neurotoxic effects of glutamate to treat movement disorders and reverse or prevent brain injury. Peripheral blockade of focal dyskinesias through botulinum toxin offers a useful alternative to drugs in some patients.

Neuropharmacology of progressive myoclonus epilepsy: response to 5-hydroxy-L-tryptophan

Low concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF) of patients with progressive myoclonus epilepsy (PME) suggest hypofunctional serotonergic neurotransmission. To study this hypothesis, we enrolled 6 patients with PME [Unverricht-Lündborg disease (U-L), mitochondrial encephalomyopathy, or Lafora disease] in a controlled, double-blinded, dose-ranging, cross-over add-on pilot clinical trial of 5-hydroxy-L-tryptophan (L-5-HTP) plus carbidopa after 2 other patients had received open-label L-5-HTP for compassionate use. Prestudy CSF 5-HIAA concentrations were low (< 20 ng/ml) in 6 patients regardless of the etiology of PME. One patient with U-L disease showed clinical improvement and a fivefold increase in CSF 5-HIAA, and 1 with Lafora disease showed a twofold increase in CSF 5-HIAA without improvement. A patient with Lafora disease reported enough improvement in myoclonus-evoked convulsions to continue chronic use of the drug. One patient with mitochondrial encephalomyopathy developed status epilepticus during treatment with L-5-HTP. As a group, patients had no statistically significant changes in myoclonus evaluation scale scores, subjective and objective measures of ataxia, seizure frequency, antiepileptic drug (AED) levels, or routine blood tests. These data suggest a serotonergic abnormality regardless of the underlying etiology of PME, but one that seldom responds to acute treatment with L-5-HTP.