Original articleMagnetoencephalography in the detection of focal lesions in West syndrome
Section snippets
Background
West syndrome (WS) is an age-dependent epileptic encephalopathy, and one of the intractable epilepsy syndromes of childhood. Many brain disorders, including tuberous sclerosis, congenital brain malformation, perinatal hypoxic ischemic encephalopathy, and meningitis can induce WS. WS is classified as a cryptogenic or symptomatic generalized epilepsy in the international classification of epilepsy syndromes [1]. However, it is well known that focal brain lesions, such as brain tumors [2], [3], [4]
Methods
Patients with WS or who had previously had WS were included in this study. We defined WS as characteristic infantile spasms and hypsarrhythmia in the EEG, so patients over 12 months old were also included. In total, 14 patients were included in this study, including six boys and eight girls, 3 months to 6 years old at the time of the MEG recording. Informed consent was obtained from the parents of all patients.
All patients underwent MRI around the time that the MEGs were recorded. MEGs were
Results
MEG was used to examine the dipole source of epilepsy in 14 patients with WS. We were able to estimate dipoles in all patients by MEG. We estimated many dipoles in each patient and classified the MEG findings into three types according to the dipole distribution pattern (Fig. 1). Dipoles distributed over a wide brain area were designated as pattern W, in which the dipole direction is random. Cases in which dipoles were not distributed all over the cortex but were distributed bilaterally over
Discussion
WS is classified as cryptogenic or symptomatic generalized epilepsy in the international classification of epilepsy syndromes [1]. The origin of the spasms and hypsarrhythmia is still under discussion. Many pathological [14], radiological [15], and electrophysiological [16], [17] studies have suggested that the brainstem is involved in WS patients. Recently, the corticotropin-releasing hormone (CRH) theory was proposed, which holds that abnormally increased CRH synthesis and activity, secondary
Acknowledgements
This study was partially supported by the Inverse Problem project of the RFTF program, JSPS, a research grant for nervous and mental disorders from the Ministry of Health and Welfare, and a Grant-in-Aid for Scientific Research from the Ministry of Education, Japan.
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