Abstracts

Rationale: EEG finding of hypsarrhythmia in West syndrome is characterized by very high amplitude and irregular slow waves with multifocal epileptiform discharges. It is often difficult to determine epileptogenic zone within hypsarrhythmia. We performed magnetoencepharography (MEG) analysis of hypsarrhythmia to estimate epileptogenic zone in a patient with West syndrome and right medial temporal lobe tumor. Normal 0 0 2 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:????; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0mm 5.4pt 0mm 5.4pt; mso-para-margin:0mm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.5pt; mso-bidi-font-size:11.0pt; font-family:"Century","serif"; mso-ascii-font-family:Century; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Century; mso-hansi-theme-font:minor-latin; mso-font-kerning:1.0pt;} Methods: MEG was performed in a magnetically shielded room using a 160-channel gradiometer (Ricoh Company, ltd, Japan) with a 5000 Hz sampling rate. EEG was simultaneously recorded using 8 scalp electrodes, placed according to the international 10–20 system. We investigated epileptogenic zone using a single dipole method to project equivalent current dipoles (ECDs) Results: The patient was 2 years and 3 months old. He started to have clusters of seizures that consisted of short upper limb jerks at 1 year and 10 months. Interictal EEG showed periodic hypsarrhythmia and ictal EEG revealed epileptic spasms in cluster. A tumor of multioculated cystic structures was pointed out in the right mesial temporal lobe on MRI. Spasms were not contrled by levetiracetam and topiramate, and his psycho-motor development was arrested. FDG-PET showed hypometabolism in the lesion and surrounding areas. MEG and EEG showed no localized change of amplitude and frequency in hypsarrythmia, but the spikes of right hemipphere preceded periodic hypsarrhythmia. By single dipole analysis equivalent current dipoles at the beginning of periodic hypsarrhytmia were clustered in the right temporal lobe. We performed right temporal lobectomy and he has been free of seizures. He gradually has caught up on psycho-motor development. In the present study, MEG analysis of the beginning of hypsarrhythmia successfully localized epileptogenic zone in a patient with West syndrome and brain tumor. MEG is useful to detect cortical epileptogenic activities that trigger brain stem and evolve to widespread EEG abnormality of hyparhythmia. Conclusions: MEG is useful to localize cortical epileptogenic zone that evolve to hypsarrhythmia in West syndrome caused by focal cortical lesions. Funding: none