Strychnine therapy in nonketotic hyperglycinemia.

Nonketotic hyperglycinemia is an inborn error of metabolism resulting from a defect in the glycine cleavage enzyme system. It is characterized biochemically by elevated concentrations of glycine in blood, spinal fluid, and urine. Previous therapies which have been directed toward reducing the glycine concentration in plasma and CSF have not been successful in preventing neurological deterioration, which may be the result of the role of glycine as an inhibitory neurotransmitter. Strychnine treatment was initiated because it is a specific antagonist of glycine at postsynaptic membranes. The patient reported here has shown clinical and EEG improvement while taking strychnine in conjunction with sodium benzoate.