Anatomical Variations of the Trigeminal Arachnoid Membrane: Implications for Microvascular Decompression Surgery in Trigeminal Neuralgia.

Objective: This study aimed to analyze the anatomic variations of the trigeminal arachnoid membrane (TM) and evaluate its implications for microvascular decompression (MVD) surgery in patients with trigeminal neuralgia (TN). Understanding the structural variations of TM is essential for improving surgical outcomes.

Methods: A retrospective analysis was conducted on 377 TN patients who underwent MVD between January 2017 and December 2023. Intraoperative video recordings were reviewed to classify the TM into 4 subtypes based on consistency, opacity, and thickness. Patients were followed for at least 10 months, with surgical techniques, including trigeminal nerve isolation, utilized to manage neurovascular conflicts and arachnoid adhesions.

Results: The TM was classified into 4 subtypes: absent (10.3%), filamentous (41.1%), membranous (43.5%), and thickened (5.1%). Neurovascular conflicts were present in 97.3% of cases, with the superior cerebellar artery being the most common offending vessel. TM subtypes influenced the complexity of the surgery, with thicker and more opaque TMs presenting challenges in visualization and nerve decompression.

Conclusions: The anatomic variations of TM play a critical role in MVD for TN. Understanding these subtypes enables more precise surgical planning, potentially reducing complications and recurrence. Standardized protocols for managing arachnoid membranes could improve outcomes and reduce the recurrence of TN symptoms. Future research should focus on developing advanced surgical tools and techniques to address the challenges posed by TM, particularly the thickened subtype.