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  • Real-Time Evaluation of Anterior Choroidal Artery Patency During Aneurysm Clipping

    Final Number:

    Jay Won Rhee MD; Vikram V. Nayar MD; robert E minahan M.D.; allen S mandir M.D., Ph.D.; Christopher Gene Kalhorn; Kevin M. McGrail MD

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2014 Annual Meeting

    Introduction: Electrophysiologic monitoring during aneurysm surgery typically utilizes somatosensory evoked potentials and the electroencephalogram, neither of which would detect occlusion of the anterior choroidal artery. We evaluate the clinical utility of direct cortical motor evoked potential (MEP) monitoring during aneurysm clipping, as a real-time assessment of arterial patency, prior to performing indocyanine green videoangiography.

    Methods: Direct cortical MEPs were recorded in 3 patients undergoing surgery for aneurysms that involved or abutted the anterior choroidal artery. After the dural opening, a subdural 8-electrode strip was placed over the primary motor cortex. Serial MEP recordings were subsequently obtained. A significant change in MEPs after clip placement would prompt immediate inspection, and removal or repositioning of the clip. If clip placement appeared satisfactory and MEP recordings were stable, then an intraoperative indocyanine green videoangiogram was performed, to confirm obliteration of the aneurysm and patency of arteries.

    Results: Three patients underwent successful clipping of posterior communicating artery aneurysms and an anterior choroidal aneurysm with direct cortical MEP monitoring, with good clinical and radiographic outcomes. In two patients, no changes in MEP amplitudes were observed following permanent clip placement. In one patient, a profound decrease in MEP amplitude occurred 220 seconds after placement of a permanent clip on a large posterior communicating aneurysm. Inspection revealed that the anterior choroidal artery was kinked. The clip was immediately removed, and MEP signals returned to baseline shortly thereafter. A clip was then optimally placed, and the patient awoke without neurologic deficit.

    Conclusions: Direct cortical MEPs are a useful adjunct to standard electrophysiologic monitoring in aneurysm surgery, particularly when the anterior choroidal artery or lenticulostriate arteries are at risk. When these arteries are occluded, infarction may occur before the occlusion is detected by indocyanine green videoangiography or intraoperative angiography. The use of MEPs allows real-time detection of ischemia to subcortical motor pathways.

    Patient Care: Real time intraoperative direct cortical MEPs may detect subcortical motor tract ischemia that may otherwise remain silent traditional neuromonitoring, ultimately making aneurysm clipping procedures more safe.

    Learning Objectives: explore the utility of direct cortical motor evoked potentials in aneurysm clipping surgery.


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