The occurrence of brain damage in 19 patients (13 girls and 6 boys) with glycogen storage disease type I (GSDI) was evaluated at the Universita “Federico II”, Naples, Italy. Performance ability as measured on Wechsler IQ tests showed lower scores in patients compared to controls (p<0.05). The prevalence of abnormal EEG findings (26.3% vs 2.6%), VEPs (38.4% vs 7.7%), SEPs (23% vs 0%), and BAEPs abnormalities (15.7% vs 0%) was higher in patients than controls (p<0.05). MRI showed abnormalities (dilated occipital horns, hyperintensity of subcortical white matter) in 8/14 (57.1%) patients and none of controls. Performance ability and BAEP abnormalities correlated significantly with the frequency of admissions for hypoglycemia. EEG abnormalities correlated with poor dietary compliance. 
COMMENT. GSDI is characterized by hypoglycemia, hyperlactic acidemia, and hepatorenal enlargement. Neonatal and recurrent hypoglycemia play a key role in causing brain damage in GSDI, and dietary compliance is essential in treatment.