Fully Endoscopic Microvascular Decompression for Hemifacial Spasm

Introduction: Hemifacial spasm is a hyperactivity disorder of the facial nerve, classically treated with microvascular decompression of the facial nerve at the root entry zone. While typically done using microsurgical technique with the assistance of an operative microscope, current advances in endoscopic technology have allowed for a fully endoscopic approach to basal cisterns and the cerebello-pontine (CP) angle. We present a single surgeon’s series of patients, focusing on surgical technique and outcomes.

Methods: Patients were retrospectively enrolled in this IRB approved study. Dr. John Y.K. Lee operated on all enrolled patients in the University of Pennsylvania Health System between January 2011 and January 2016. Patients that underwent microscope only or endoscope-assisted surgery were not included (n = 7). Likewise, patients with hemifacial spasm related to a CP angle mass were also excluded (n = 2). Patient self-reported results and disability outcomes at follow-up were assessed.

Results: 20 patients met inclusion criteria and were enrolled in the current study. Neuro-monitoring of the facial nerve (lateral spread response) and brainstem auditory evoked potentials (BAERs) were consistently utilized. All procedures were performed according to standardized endoscopic technique through a small (<1cm dural opening) retrosigmoid craniectomy. Following dural incision, zero degree and angled endoscopes were used to visualize the CP angle and the facial nerve. The offending vessel, once visualized, was decompressed from the nerve using Teflon pads. The anterior inferior cerebellar artery (AICA) was visualized as the compressing vessel in 13/20 (65%) of cases, the vertebral artery in 3/20 (15%) of cases, 2/20 (10%) patients had compression by an unnamed perforator vessel, in 1 (5%) case, compression was from a large vein, and in 1 (5%) case, no offending vessel was visualized.

Conclusion: The fully endoscopic microvascular decompression of the facial nerve is a safe and effective technique, utilizing a small craniectomy. The 2.7mm endoscope allows for excellent visualization of the CP angle, facile identification and decompression of compressive vessels, all while maintaining a minimal craniectomy and skin incision. Further study is warranted to compare outcomes of fully endoscopic MVD and microscopic MVD.