Distal Arterial Decompression of Trigeminal Nerve Near Meckel's Cave Improves Facial Pain Outcomes during Fully Endoscopic Microvascular Decompression

Objective: Proximal arterial decompression of the trigeminal nerve has been the standard of care since Dr. Jannetta introduced microvascular decompression in 1967. The introduction of the endoscope for a fully endoscopic MVD (E-MVD) provides the ability to identify distal compression near Meckel's cave, which may be missed with conventional microscope. The relevance of distal vascular compression; however, is unclear. In this study, we correlate pain outcomes with proximal versus distal vascular compression.

Methods: A 6-year analysis of operative videos and outcomes of patients undergoing E-MVD for Burchiel type 1 (>50% sharp/shooting) or type 2 (<50% sharp/shooting) yielded 224 patients. Before and 1 month after surgery, patients completed a reliable, validated, multidimensional facial pain outcome tool—Penn Facial Pain Scale (aka BPI-Facial) as well as the global impression of change (7-point Likert scale). On video analysis, the nerve was visualized from brainstem to its entry into Meckel's cave. Vascular compression (VC) was defined as proximal (REZ to midpoint) and/or distal (midpoint to Meckel's cave). We classified VC into four types: VC Type 1, proximal arterial compression (alone or in combination with distal compression); VC Type 2, proximal venous compression (alone or in addition to distal compression); VC Type 3, distal arterial compression (alone or in combination with distal venous compression); VC Type 4, distal venous compression only. We posit that VC Types 1 and 2 are well visualized by the microscope and outcomes have been described previously. In contrast, VC Types 3 and 4 are best visualized with the endoscope, and outcomes need to be studied. We constructed a multivariate model considering VC type, demographic and clinical variables. Major symptomatic improvement was defined by patient global impression of change: “very much improved” or “much improved.”

Results: VC Type 1—observed in 65% (141/217) of patients with 89% (104/117) major symptomatic improvement. VC Type 2—observed in 16.6% (36/217) with 86.6% (26/30) major symptomatic improvement. VC Type 3—observed in 10.1% (23/217) with 100% (17/17) major symptomatic improvement. VC Type 4—observed in 6.5% (14/217) with 83% (10/12) major symptomatic improvement. A multivariate model demonstrates distal venous decompression as a significant negative predictor of outcomes with a regression coefficient of −2.0374. Advanced age is a significant positive predictor of outcome.

Conclusion: The adoption of the endoscope allows for enhanced visualization of neurovascular conflict, including both distal arterial and venous compression which are difficult to visualize with microscope alone. Using the Penn Facial Pain Scale, we conclude that patients with only distal venous compression are not as likely to achieve pain relief as all other types of compression. Nevertheless, outcomes in patients who undergo distal decompression are still excellent, especially if compression is arterial.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
12 February 2021