Cortical Hypometabolism and Delayed Myelination in West Syndrome

Summary: Purpose: We examined the relation between cortical hypometabolism and delayed myelination in patients with West syndrome (WS).
Methods: Serial positron emission tomography (PET) with ^18F]fluorodeoxyglucose (^18F]FDG) and magnetic resonance imaging (MRI) were performed in 18 patients with WS, first at the onset of epileptic spasms and later at age 10 months. The age at onset of seizures ranged from 2 to 7 months. Ten patients were diagnosed as having cryptogenic WS and 8 as having symptomatic WS.
Results: Cortical hypometabolism was detected in many patients at onset of epilepsy, but disappeared later, whereas delayed myelination tended to become evident with age. PET showed diffuse or focal cortical hypometabolism in 12 patients at onset, but in only 6 patients at age 10 months. MRI showed delayed myelination in only 2 patients at onset of epilepsy, but the number of patients with delayed myelination increased to 12 at age 10 months. Delayed myelination was more often present in patients with cortical hypometabolism. Delayed myelination was noted in 11 (85%) of 13 patients with cortical hypometabolism on first or second PET scans, but in only 1 (20%) of 5 patients who did not show PET abnormalities. Hypometabolism on the first or second PET scan was positively correlated with delayed myelination at age 10 months.
Conclusions: In patients with WS, assessing myelination with MRI again at age 8–10 months is important even when MRI at the onset of epilepsy appears normal. Serial MRI and PET scans disclose more detailed pathophysiology of WS.