Abstract
Background: According to the international classification of epilepsy syndromes, West
syndrome (WS) is a form of generalized epilepsy. However, it is known that localized
lesions can induce WS and that patients with WS often subsequently develop focal seizures.
We evaluated such patients using magnetoencephalography (MEG).
Method: Fourteen patients of 3 months to 6 years of age who had or who had previously
had WS were examined. MEGs were recorded using a laying-type whole-cortex MEG system
with a 160-channel first-order gradiometer. Twelve-channel electroencephalography
(EEG) and one-channel electrocardiography (ECG) were simultaneously recorded. Equivalent
current dipoles were estimated at the point of spikes on the EEG.
Results: Patients were classified by magnetic resonance imaging (MRI) findings into
a focal lesion group (group F, n=7) and a non-focal lesion group (group N, n=7). The dipoles estimated from the MEG were classified into three groups: W, with
the dipoles distributed over a wide brain area (n=7); WC, dipoles distributed over a wide area along with a dense dipole distribution
in a specific cortical area (n=3); and C, closed dipole distribution in a unilateral cerebral focal area (n=4). Patients were also classified by the stage of the disease during which the MEG
was recorded, and by the type of seizure they experienced. Those with hypsarrhythmia
examined early in the disease all had pattern W regardless of their lesion group,
whereas those examined later exhibited more diverse dipole patterns that corresponded
to seizure type.
Conclusions: Dipoles were distributed widely over bilateral cerebral cortex when patients
had infantile spasms with hypsarrhythmia whether or not they had focal lesions. The
dipole distribution pattern in MEG changed according to changes in seizure type.
Keywords
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Article info
Publication history
Accepted:
June 17,
2001
Received in revised form:
June 14,
2001
Received:
May 17,
2001
Identification
Copyright
© 2001 Elsevier Science B.V. Published by Elsevier Inc. All rights reserved.
