Biotin-responsive infantile encephalopathy: EEG-polygraphic study of a case.

A case of an infant suffering from progressive lethargy, sparse scalp hair, autistic-like behavior, myoclonias, and drug-resistant generalized seizures is reported. Laboratory investigations revealed, in the absence of metabolic acidosis, an increased urinary excretion of 2-ketoglutaric acid and a small peak of 3-hydroxyisovaleric acid. The serum biotinidase activity was 0.15 nmol min-1 ml-1 (normal range 5.2 +/- 0.9) in the propositus and 0.310 and 0.420 in her father and mother, respectively. The interictal EEG showed multifocal abnormalities; numerous seizures were recorded, with the pattern of true tonic-clonic fits, exceptional in infancy. Also myoclonias, auditory myoclonus, and repetitive startles were documented. Because of dramatic improvement of all symptoms and signs after starting biotin (5 mg twice daily), the authors suggest a therapeutical trial in all drug-resistant infantile seizures.