1 National Institutes of Health, Bethesda
Severe intractable seizures are frequent manifestations of nonketotic hyperglycinemia. Because levels of urinary and plasma glycine have been reported to be elevated by valproate in patients with seizures but no evidence of hereditary hyperglycinemia,1,2 it has been assumed that the agent is contraindicated for the therapy of convulsive states associated wtih nonketotic hyperglycinemia. This conclusion was recently stated, for example, at an international congress on human genetics.3
We regard this assumption as unwarranted. We have administered valproate to two nonketotic hyperglycinemic patients and monitored glycine levels in their cerebrospinal fluid. It is the elevated CSF glycine which has been postulated to result in the encephalopathy in nonketotic hyperglycinemia.4