Transient effect of L-tryptophan in progressive myoclonus epilepsy without Lafora bodies: clinical and electrophysiological study.

A double-blind crossover trial with 2 g L-tryptophan and placebo was carried out with five familial and two sporadic patients with progressive myoclonus epilepsy (PME) without Lafora bodies. L-Tryptophan improved the clinical condition in six out of seven patients. Clinical improvement in ambulation, myoclonic jerks, and general condition was most evident. The change was statistically significant. In visual assessment of EEGs, the amount of paroxysmal activity and dysrhythmia of the background activity decreased in six out of seven patients on L-tryptophan. The quantitative EEG revealed a decrease in the power bands of theta, alpha, and beta activity in five of six patients on the second day of L-tryptophan treatment. In familial PME cases, the responses were consistently beneficial. With long-term L-tryptophan therapy, the effect disappeared or was even reversed in three of seven patients after 3 to 4 weeks. These findings indicate that therapy with serotonin precursors is worthy of further trial in PME and that deficient tryptophan metabolism may play a part in the etiology of PME without Lafora bodies.