Autoantibodies to glutamic acid decarboxylase in palatal myoclonus and epilepsy

We report the presence of serum autoantibodies directed against glutamic acid decarboxylase in a patient with epilepsy and palatal myoclonus not associated with brain lesions. Glutamic acid decarboxylase antibody reactivity was dependent on the presence of carboxy-terminal amino acids, similar to that reported in patients with stiff-man syndrome. Marked reduction in the frequency of epileptic attacks and improvement in palatal myoclonus occurred when benzodiazepine was administered and phenytoin was gradually tapered. Testing for anti-glutamic acid decarboxylase antibodies may be indicated in patients with palatal myoclonus and with convulsive disorders refractory to therapy.