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  • Feasibility of Magnetoencephalography Following Endovascular Treatment for Aneurysm Rupture

    Final Number:

    Leo da Costa MD; Allison Bethune MSc; Margot J Taylor PhD; Ben T. Dunkley; Elizabeth W. Pang

    Study Design:
    Laboratory Investigation

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2015 Annual Meeting

    Introduction: Aneurysmal subarachnoid hemorrhage (aSAH) still carries very high morbidity despite advances in care. Even amongst patients with good outcomes, memory, language, and executive function impairments are common complaints. No objective imaging marker for diagnosis and monitoring of neurocognitive complaints is available for these patients. We explored the use of magnetoencephalography (MEG) – a neurophysiological functional imaging technique - in aSAH patients following endovascular aneurysm coiling.

    Methods: Enrollment was limited to patients with coiled ruptured aneurysms, good outcome (GOS 4 or 5) and no ischemic lesions on MRI, and matched healthy controls. Resting-state MEG data and anatomical MRI were acquired. A multi-sphere head model was constructed for each individual’s brain and normalized to MNI space using SPM2. Cortical and sub-cortical voxels of interest were identified, and time series (virtual electrodes) were reconstructed using a vector beamformer. Seed locations were chosen and spectral power density estimated for each location and averaged across the brain to derive mean signal power. Virtual-sensor data closest to the coil location were extracted and visually assessed for signal quality.

    Results: Thirteen aSAH patients and 13 controls completed MEG evaluation. Time from aSAH to testing was 18.8 months. Average test time was 80 minutes. Mean age was 57 years; the majority of aneurysms were midline (62%). Mean signal power was similar across groups, with no significant spectral alterations among aSAH patients. Virtual-sensor data closest to the coil in aSAH patients showed comparable signal on matched locations in control participants, i.e. no artifact from the coils.

    Conclusions: We show the technical feasibility of MEG assessment after coiling of ruptured aneurysms. The presence of coils do not alter MEG signal quality or strength, and therefore the optimal temporal and spatial resolution of MEG holds potential for investigating the neurophysiological basis of neuro-behavioural deficits after intracranial aneurysm rupture.

    Patient Care: This work holds clinical potential in quantifying and monitoring neurobehavioral sequelae commonly experienced after aSAH.

    Learning Objectives: Participants should be able to: 1) understand the nature of cognitive sequelae after aSAH, and 2) appreciate how robust and reliable MEG recordings are feasible in an aSAH population despite endovascular coil placement


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