The oculomotor-tentorial triangle. Part 2: A microsurgical workspace for vascular lesions in the crural and ambient cisterns

Justin R Mascitelli, Sirin Gandhi, Ali Tayebi Meybodi, Michael T. Lawton

Research output: Contribution to journalArticlepeer-review

Abstract

OBJECTIVE Pathology in the region of the basilar quadrifurcation, anterolateral midbrain, medial tentorium, and interpeduncular and ambient cisterns may be accessed anteriorly via an orbitozygomatic (OZ) craniotomy. In Part 1 of this series, the authors explored the anatomy of the oculomotor-tentorial triangle (OTT). In Part 2, the versatility of the OTT as a surgical workspace for treating vascular pathology is demonstrated. METHODS Sixty patients with 61 vascular pathologies treated within or via the OTT from 1998 to 2017 by the senior author were retrospectively reviewed. Patients were grouped together based on pathology/surgical procedure and included 1) aneurysms (n = 19); 2) posterior cerebral artery (PCA)/superior cerebellar artery (SCA) bypasses (n = 24); 3) brainstem cavernous malformations (CMs; n = 14); and 4) tentorial region dural arteriovenous fistulas (dAVFs; n = 4). The majority of patients were approached via an OZ craniotomy, wide sylvian fissure split, and temporal lobe mobilization to widen the OTT. RESULTS Aneurysm locations included the P 1 -P 2 junction (n = 7), P 2A segment (n = 9), P 2/3 (n = 2), and basilar quadrification (n = 1). Aneurysm treatments included clip reconstruction (n = 12), wrapping (n = 3), proximal occlusion (n = 2), and trapping with (n = 1) or without (n = 1) bypass. Pathologies in the bypass group included vertebrobasilar insufficiency (VBI; n = 3) and aneurysms of the basilar trunk (n = 13), basilar apex (n = 4), P 1 PCA (n = 2), and s 1 SCA (n = 2). Bypasses included M 2 middle cerebral artery (MCA)–radial artery graft (RAG)–P 2 PCA (n = 8), M 2 MCA–saphenous vein graft (SVG)–P 2 PCA (n = 3), superficial temporal artery (STA)–P 2 PCA (n = 5) or STA–s 1 SCA (n = 3), s 1 SCA–P 2 PCA (n = 1), V 3 vertebral artery (VA)–RAG–s 1 SCA (n = 1), V 3 VA–SVG–P 2 PCA (n = 1), anterior temporal artery–s 1 SCA (n = 1), and external carotid artery (ECA)–SVG–s 1 SCA (n = 1). CMs were located in the midbrain (n = 10) or pontomesencephalic junction (n = 4). dAVFs drained into the tentorial, superior petrosal, cavernous, and sphenobasal sinuses. High rates of aneurysm occlusion (79%), bypass patency (100%), complete CM resection (86%), and dAVF obliteration (100%) were obtained. The overall rate of permanent oculomotor nerve palsy was 8.3%. The majority of patients in the aneurysm (94%), CM (93%), and dAVF (100%) groups had stable or improved modified Rankin Scale scores. CONCLUSIONS The OTT is an important anatomical triangle and surgical workspace for vascular lesions in and around the crural and ambient cisterns. The OTT can be used to approach a wide variety of vascular pathologies in the region of the basilar quadrifurcation and anterolateral midbrain.

Original languageEnglish (US)
Pages (from-to)1435-1445
Number of pages11
JournalJournal of Neurosurgery
Volume130
Issue number5
DOIs
StatePublished - May 1 2019
Externally publishedYes

Keywords

  • Ambient cistern
  • Brainstem cavernous malformation
  • Crural cistern
  • Oculomotor triangle
  • Pontomesenphalic junction
  • Posterior circulation aneurysms
  • Posterior circulation revascularization
  • Surgical technique
  • Tentorial dural arteriovenous fistula
  • Vascular disorders

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology

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