Magnetoencephalography in West syndrome

Abstract Background : Localized lesions induce West syndrome (WS), and patients with West syndrome often subsequently develop focal seizures. Methods : We evaluated patients with West syndrome using magnetoencephalography (MEG). Fourteen patients who currently or previously had West syndrome were examined at 3 months to 6 years of age. MEGs were recorded using the 160-channel, whole-head, laying-type MEG system. Equivalent current dipoles were estimated at the time of spikes on the EEG. Results : The patients were classified according to MRI findings. Seven patients were in the focal lesion group (group F) and seven in the non-focal lesion group (group N). Dipoles were distributed over a wide brain area in seven patients (pattern W). Three patients had dipoles distributed over a wide area along with a dense dipole distribution in a specific cortical area (pattern WC). Four patients had a closed dipole distribution in a unilateral cerebral focal area (pattern C). Dipoles were distributed widely over the bilateral cerebral cortex in patients with infantile spasms with hypsarrhythmia. Conclusions : The change in the dipole distribution pattern in the MEG of patients with West syndrome correlated with the seizure type.