Cognitive function and neurophysiological evaluation in early-treated hypothyroid children

In this study, we assessed cognitive function and neurophysiological develo pment in congenitally hypothyroid (CH) children. We performed a cross-secti onal study at the outpatient Pediatric Clinic and Department of Neurophysio logy at San Raffaele Hospital, Milan. The study enrolled 25 CH patients (6. 00-10.83 years of age) detected by neonatal screening, and 34 healthy contr ol children (4-11 years of age). Patients and controls had comparable score s at neuropsychological tests (WISC-R), and at auditory P300 tests. In cont rast, we found significantly longer LLSEP latencies in CH patients (p < 0.0 3). CH patients treated 30 days after birth showed lower scores at neuropsy chological tests, but not at neurophysiological tests, compared to patients who started the replacement therapy earlier. Patients with more severe fet al hypothyroidism (T4 levels at diagnosis <less than or equal to> 2 mug/dl) had lower neuropsychological scores, and similar neurophysiological result s, compared with patients with moderate fetal hypothyroidism. The severity of fetal hypothyroidism and early treatment influence the mental outcome of CH patients. Neurophysiological results show that central nervous system d amage occurs in some patients despite early treatment.