Screening of Inherited Metabolic Disorders in Infants with Infantile Spasms

The objective of this study is to explore the incidence of inherited metabolic disorders (IMD) in infants with infantile spasms (IS), with an attempt to improve the early diagnosis and etiological and symptomatic treatment. Urine and blood samples were collected from 60 IS patients and analyzed for the quantification of amino acids, organic acids, and fatty acids by gas chromatography-mass spectrometry and tandem mass spectrum. Routine urine tests, hepatic function tests, blood biochemistry, brain imaging, as well as examinations of the brain stem auditory/visual evoked potentials were also examined. In addition to antiepileptic therapy, etiological and symptomatic treatments were also conducted in infants with confirmed IMD and the follow-up lasted for 6 months in these pediatric patients. Metabolic disorders were found in 28 (46.67 %) of 60 IS infants, among them 13 (21.67 %) were confirmed to be with IMD. Twelve of these 13 IS patients with definite IMD diagnoses (92.31 %) experienced varying degrees of delayed development of intelligence and motor function, 8 patients (61.54 %) had abnormal cranial CT or MRI findings, 11 patients (84.61 %) had abnormal brain stem evoked potentials, 4 patients (30.77 %) had abnormal hepatic functions, 3 patients (23.07 %) had abnormal blood biochemistry, 2 patients (15.38 %) had positive (+ to ++) results for routine urine ketones, and 2 patients (15.38 %) had skin lesions. After treatment in children who were diagnosed IMD, the well controlled epileptic seizures and the satisfactory developments in mental and motor were found in 4 cases of methylmalonic acidemia, 2 cases of classical phenylketonuria, and one case of biotin deficiency disease, glutaric acidemia type I, and 4-hydroxybutyric aciduria in each. IMD is a key biological cause in IS. Early screening for IMD is warranted in IS infants to facilitate the improvement for the prognosis and an early etiological treatment.