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Transtubular Microvascular Decompression for Trigeminal Neuralgia
Background: Vascular compression of the trigeminal nerve root, by either an artery or a vein, is the cause of trigeminal neuralgia (TN) in 80 to 90% of cases. Microvascular decompression (MVD), as first described by Jannetta in 1967, still represents the gold standard for treatment of TN. The complication rate of MVD is low, but there remains the risk of permanent hearing impairment from damage to the vestibulocochlear nerve caused by excessive retraction of the cerebellum. We investigate a less invasive approach using a minimally invasive tubular retractor system and assess the feasibility of this approach using both microscopic and endoscopic techniques.
Methods: MVD was performed in five preserved cadaveric heads. A 1.5-cm retrosigmoid keyhole craniotomy was used to expose the upper neurovascular structures of the cerebellopontine angle. A ViewSite Brain Access System of tubular retractors (Vycor Medical, Inc., Boca Raton, Florida, United States) was placed into the keyhole and advanced into the lateral aspect of the upper cerebellopontine angle. The retractor was then secured to supply minimal cerebellar retraction. The trigeminal roots were easily identified and their relationships with neighboring vessels were thoroughly examined.
Results: The tubular retractor applied rigid, constant, and equally distributed pressure on the cerebellum, and allowed the surgeon to reach the CPA without undue cerebellar retraction. Endoscopic instruments and an electric drill were passed through the tubular retractors without difficulty, and excellent visualization of the surrounding neurovascular structures was achieved. Enhanced intraoperative visualization is clinically beneficial as the majority of failed MVD's are caused by misidentification of the offending vessel because of insufficient surgical exposure.
Conclusion: The use of transtubular retractors in trigeminal MVD is both feasible and effective in avoiding excessive retraction. The tubular retractor reduces the risk of damage to the surrounding nerves and provides excellent surgical maneuverability. Further clinical studies are necessary to determine clinical efficacy.