An Unusual Cause of Intraoperative Somatosensory-Evoked Potential Signal Loss during Intracranial Aneurysm Clipping

Multimodal neuromonitoring plays a pivotal role in the prevention of perioperative stroke during microsurgical occlusion of an aneurysm. Several modalities are available for the same, and by appropriately combining them, depending on the vascular territory of interest, their diagnostic precision can be maximized. Any intraoperative change in evoked potentials during aneurysm clipping should be addressed immediately. A root cause analysis using a checklist can identify and rectify reversible causes, avoiding morbidity. In this report, we present a case of surgical clipping of a right middle cerebral artery aneurysm where the intraoperative somatosensory-evoked potential changes occurred secondary to an ipsilateral extradural hemorrhage. This is the first report describing such a rare phenomenon, and addressing it promptly led to a complete neurological recovery.