2026 Proffered Presentations
S142: ENDOSCOPIC ENDONASAL APPROACH WITH PITUITARY TRANSPOSITION FOR RESECTION OF MIDBRAIN CAVERNOUS MALFORMATIONS IS A SAFE AND EFFECTIVE ALTERNATIVE TO OPEN APPROACHES: A CASE SERIES AND ANATOMICAL CONSIDERATIONS USING CADAVERIC DISSECTIONS AND HDFT
Robert J Dambrino, MD, MPH1; Cleiton Formentin1; David T Fernandez-Cabral, MD1; Yun-Kai Chan1; Arseniy Pichugin1; Garrett W Choby, MD2; Eric W Wang, MD2; Carl H Snyderman, MD, MBA2; Paul A Gardner, MD1; Georgios A Zenonos, MD1; 1University of Pittsburgh Medical Center, Department of Neurological Surgery; 2University of Pittsburgh Medical Center, Department of Otolaryngology
Introduction: Midbrain cavernous malformations are challenging to treat given their anatomical location within eloquent brainstem tissue surrounded by critical white matter tracts and perforating vessels. Traditional open approaches require significant brain retraction and indirect working angles. This study reports a case series of 3 midbrain cavernous malformations arising to the surface of the cerebral peduncles at the interpeduncular cistern undergoing an endoscopic endonasal approach for resection (EEA) as well as defines anatomical considerations with high-definition fiber tractography (HDFT) and anatomical cadaveric dissections
Methods: 3 patients with midbrain cavernomas with lesions rising to the surface of the cerebral peduncles with (HDFT) revealing corticospinal tracts lateral to the lesion underwent EEA and pituitary transposition for resection of lesion. Ten silicone-injected cadaveric specimens underwent stepwise endoscopic endonasal dissection including transsphenoidal transcavernous approach, unilateral and bilateral posterior clinoidectomy, and division of the diaphragma sellae. Midbrain exposure areas, upper clivus drilling percentages, and oculomotor nerve lengths were measured using stereotactic navigation. Relevant vascular anatomy of the P1 segment posterior cerebral artery was characterized. HDFT was performed on 32 normal subjects from the Human Connectome Project to analyze corticospinal tract and oculomotor nerve anatomical variations.
Results: In the clinical series, three patients with mesencephalic cavernous malformations underwent endoscopic endonasal transcavernous resection with interdural pituitary transposition. Case 1: A 25-year-old woman with recurrent hemorrhage achieved gross total resection with transient worsening of pre-existing internuclear ophthalmoplegia and hemiparesis that returned to baseline at one month. Case 2: A 34-year-old man with complete oculomotor palsy underwent successful resection with improvement in third nerve function and temporary diabetes insipidus requiring DDAVP. Case 3: A 52-year-old female with 2 years of progressive diplopia found to have a partial left third nerve palsy. Complete resection was achieved with some transient worsening of her third nerve palsy. No CSF leaks occurred in any patient, and all achieved gross total resection as confirmed on postoperative imaging. The variations in basilar perforator anatomy were investigated with anatomical dissections, and the spectrum of distances between the corticospinal tracts and the intra-axial course of the oculomotor nerves were evaluated with HDFT (Figure 2)
Conclusions: The endoscopic endonasal transcavernous approach with posterior clinoidectomy provides excellent visualization of the ventral midbrain and interpeduncular cistern and is safe in providing gross total resection in a case series of three patients. This minimally invasive approach offers an alternative to traditional transcranial routes for carefully selected mesencephalic cavernous malformations, particularly those with midline or ventral locations, while minimizing brain retraction and optimizing working angles for safe resection.
