Neuromagnetic crossed cerebellar activation during seizures arising from the motor cortex

Abstract

Event Abstract Back to Event Neuromagnetic crossed cerebellar activation during seizures arising from the motor cortex Ismail Mohamed1*, Hiroshi Otsubo2, Paul Ferrari3, Carter Snead2 and Douglas Cheyne4 1 University of Calgary, Department of Pediatrics, Alberta Children's Hospital, Canada 2 Hospital for Sick Children, Neurology Division, Canada 3 Hospital for Sick Children, Program in Neurosciences and Mental Health, United States 4 University of Toronto, Program in Neurosciences and Mental Health, Hospital for Sick Children, and Department of Medical Imaging, Canada Crossed cerebellar hyperperfusion is a relatively rare phenomenon observed in ictal SPECT /PET scans performed during seizures arising predominantly from the frontal lobe [1]. The phenomenon is thought to originate from the spread of ictal discharges through efferent projections to the contralateral cerebellar hemisphere. We report on the neuromagnetic correlates of crossed cerebellar activation in a child with seizures arising from the motor cortex. The child is a 4 ½ year old right handed boy with seizures since 1.5 years of age. His seizures consisted of left body, face and limb twitching. MEG recordings were performed utilizing whole head 151-channel axial gradiometer system (VSM MedTech Ltd) located inside a magnetically shielded room. Two typical electroclinical seizures were captured during MEG recording. MEG analysis of ictal data was performed utilizing an event-related beamformer (ERB) [2]. We computed mean source power in the 20-100 Hz frequency band over consecutive two seconds intervals starting from the magnetic seizure onset time. Based on the peak source locations as determined with the ERB, we created time series of source activity or ‘virtual sensors’ for each of the peak locations in the 20-100 Hz band. Results: Seizures lasted 26 and 53 seconds. The maximum source activity was seen over the right precentral gyrus at the onset of both seizures. Contralateral cerebellar activation was noted at the onset and peaked after 12 seconds in both seizures. Invasive video-EEG monitoring captured seizures arising from the right Rolandic region including the hand and face motor areas and concordant with the ERB seizure onset localization. Conclusion: ERB analysis of ictal MEG data demonstrated the neuromagnetic evidence and time course of crossed cerebellar activation during seizures arising from the motor cortex in a child with intractable epilepsy.