Arachnoid Membranes Around the Cisternal Segment of the Trigeminal Nerve: A Cadaveric Anatomic Study and Intraoperative Observations During Minimally Invasive Microvascular Decompression Surgery

• Published in: World neurosurgery Vol. 125; pp. e262 - e272
• Main Authors: Kurucz, Peter, Ganslandt, Oliver, Buchfelder, Michael, Barany, Laszlo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2019
• Subjects: Aged; Aged, 80 and over; Arachnoid - anatomy & histology; Arachnoid membranes; Cadaver; Endoscopic anatomy; Female; Humans; Male; Microvascular decompression; Microvascular Decompression Surgery - methods; Middle Aged; Neuroendoscopy - methods; Posterior fossa; Retrosigmoid keyhole approach; Retrospective Studies; Trigeminal nerve; Trigeminal Nerve - anatomy & histology; Trigeminal Nerve - surgery; Trigeminal neuralgia; Trigeminal Neuralgia - surgery; Retrosigmoid keyhole approach; Arachnoid membranes; Microvascular decompression; Endoscopic anatomy; Trigeminal neuralgia; Trigeminal nerve; mLMC; MVD; Posterior fossa
• ISSN: 1878-8750; 1878-8769
• DOI: 10.1016/j.wneu.2019.01.060

The minimally invasive microvascular decompression (MVD) for trigeminal neuralgia is technically a more challenging operation compared with the standard retrosigmoidal approach. Endoscopic assistance could help to widen the field of view of the microscope during MVD. An extended view around the cisternal segment of the trigeminal nerve can be achieved only with the targeted dissection of the arachnoid membranes. The goal of our study was to analyze the three-dimensional organization of these membranes around the trigeminal nerve. Microsurgical, endoscopic, and macroscopic anatomic examinations were performed on 50 fresh human cadaveric specimens. Retrospective analysis of the video documentations of 50 MVDs was performed to describe the surgical relevance of the examined membranes. The trigeminal nerve is surrounded circumferentially by 4 inner arachnoid membranes: laterally and caudally by the trigeminal membrane (TM), cranially by the superior cerebellar membrane (SCM), and medially by the junction between the cranial edge of the anterior pontine membrane and the lateral edge mesencephalic leaf of the Liliequist membrane complex. The superior cerebellar artery was located in every case cranial from the SCM. This membrane served as a safety plane to dissect the vessel from the nerve. The SCM was laterally adherent to the TM, which made the arachnoid dissection challenging. The superior petrosal vein was located cranially and laterally from the described inner arachnoid membranes, but the transverse pontine vein was embedded into the membrane complex. Knowledge of the described anatomy of the arachnoid membranes around the trigeminal nerve is essential to safely perform an MVD.