Exoscopic to Endoscopic Channel-Based Trans-Sulcal Resection of a Third Ventricular Cavernous Malformation: Technical Case Illustration.

Cavernous malformations are angiographically occult vascular hamartomas without intervening neural tissue that represent an estimated 10% of central nervous system vascular pathologies. Management is often dictated by lesion location, intranidal versus extranidal hemorrhage, presenting symptoms, acuity of onset, and surgical accessibility. Deep-seated cavernous malformations are often adjacent to eloquent structures, including functional white matter tracts that must be accounted for during surgical planning and respected during resection of the cavernoma. Exoscopic-guided channel-based approaches can help minimize retraction of brain tissue while providing a navigated, direct path to the target lesion. We report a case of an 18-year-old man who presented with seizures and was found to have a hemorrhagic third ventricular cavernous malformation resulting in hydrocephalus. A right frontal trans-sulcal approach using an exoscope and channel-based retractor was performed and directed along the long axis of the lesion to minimize displacement of surrounding eloquent structures and manipulation of the fornix. An uneventful gross total resection was achieved and confirmed using an angled endoscope to inspect the cavity walls, the "exoscopic to endoscopic or E2E approach" (Video 1). The patient developed transient short-term memory dysfunction in the immediate postoperative period, likely due to retraction of the fornix, which dramatically improved with speech therapy and rehabilitation. The patient provided informed consent for surgery and video recording.