Peer-Review ReportEndoscopic Vascular Decompression for the Treatment of Trigeminal Neuralgia: Clinical Outcomes and Technical Note
Introduction
Microvascular decompression (MVD) is an accepted and successful treatment modality for medication-resistant trigeminal neuralgia (TGN). Various vascular structures can compress the trigeminal nerve, most commonly at the dorsal root entry zone (DREZ), causing the onset of symptomatology. MVD to separate the trigeminal nerve from the offending vessel has remained a successful surgical treatment modality for TGN 2, 4, 11. Accurate localization of the area of compression is essential to maximize the rate of success for the decompression (4).
Endoscopy has provided the next step in the evolution of the vascular decompression surgical technique. In recent years, the endoscopically assisted MVD (EAMVD) has been shown to be highly successful and has gained popularity 13, 17. This modification of the original procedure involves the traditional craniotomy followed by endoscopic exploration of the localized anatomy. Endoscopy allows for greater detailed visualization of cerebellopontine angle (CPA) vasculature and structures than microscopy alone 12, 14. Several studies have found that endoscopy can accurately find the site of compression in TGN even when missed with microscopy 3, 5, 6, 7, 8. Once the area of neurovascular compromise is identified, the decompression is performed under microscopy. At this point the endoscope can be reintroduced because it allows superior visualization of the area ventral to the DREZ as compared to microscopy 8, 15.
The EAMVD has further evolved with the introduction of endoscopic vascular decompression (EVD). This procedure is performed using endoscopy alone, without the use of microscopy at any point in the procedure. Benefits of EVD include smaller craniotomy, less soft tissue dissection, and less cerebellar retraction, while maintaining optimal visualization of the neurovascular structures in the CPA. In addition, faster patient recovery is observed. The number of reports on this subject are limited; however, those published to date show that EVD is safe and highly effective 1, 8, 9, 10, 18. The purpose of this study was to report the results of the EVD procedure as performed at our institution.
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Materials and Methods
A prospective observational study was performed of all 57 patients who underwent EVD at our institution over a 5-year period, October 2005 to October 2010. Institutional review board approval was obtained for this study. All patients had preoperative Barrow Neurological Institute pain intensity score (BNI) scores of 5, had failed medical management, and had undergone preoperative magnetic resonance imaging to rule out CPA mass, aneurysm, etc. The mean age at the time of surgery was 58.3 years,
Instrumentation
In our experience with posterolateral skull base procedures, the endoscope that is primarily preferred for use is a 0° 4.0-mm rigid endoscope (Karl Storz, Tuttlingen, Germany). Upon the conclusion of the operation, a 30° 4.0-mm rigid endoscope (Karl Storz) is occasionally used to inspect the cranial nerve DREZ and surrounding areas. The 30° scope allows visualization of important structures that may be hidden throughout the procedure without the risk of retraction. Visualization of the field is
Results
Baseline characteristics of all 57 patients are shown in Table 2; all 57 patients suffered from severe pain with BNI scores of 5 prior to surgery. The postoperative results in our patients with TGN are shown in Table 3. Forty-seven of the 57 (82%) and 43 of the 57 (75%) patients immediately postoperatively and at 1-month follow-up, respectively, had complete relief of preoperative pain without the need for any medications, a BNI score of 1. One patient had both an immediate postoperative and a
Discussion
The standard open MVD procedure for the treatment of TGN has been and is a highly successful and accepted procedure. The addition of EAMVD provided improved visualization and overall outcomes to the procedure. More recently, several authors have advocated EVD without the use of microscopy at any point. We have found that the EVD procedure is both highly safe and successful, as demonstrated by the BNI pain intensity score.
A landmark study by Barker et al. (2) studied the overall outcomes of the
Conclusions
EVD is a safe and highly effective treatment modality for TGN. This procedure offers comparable results to the traditional MVD as well as EAMVD. In addition, EVD allows for smaller incisions and craniotomies and minimizes brain retraction. Hospital LOS and operative time are relatively short, without compromising the safety of the patient or decreasing the efficacy of the procedure. Future studies regarding cost-effectiveness could provide further support for EVD.
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.