Endoscopic Microvascular Decompression for Hemifacial Spasm: A Technical Case Report Demonstrating the Benefits of the Angled Endoscope and Intraoperative Neuromonitoring.

Rachel Blue,John Y.K Lee,Susanna Howard,Svetlana Kvint,Michael Spadola

doi:10.7759/cureus.16586

Abstract

A 57-year-old female with eight years of hemifacial spasm (HFS) underwent endoscopic microvascular decompression (MVD) of the facial nerve. Baseline stimulation of the zygomatic branch of the facial nerve activated at 1.2 mA. Lateral spread response (LSR) to the buccal and mandibular branches was observed at 2.2 mA. A straight endoscope was used to enter the cerebellopontine angle, allowing for visualization of the vestibulocochlear and facial nerve. Neurovascular compression was not clearly identified. A 30-degree endoscope was directed medially/inferiorly and compression at the root entry zone was identified and decompressed. Subsequent LSR to the buccal/mandibular branches was seen at 3.2 mA/3.6 mA, respectively. Additional vascular compression was suspected given persistent LSR. The 30-degree endoscope was directed laterally. Compression was seen at the porus acustics and decompressed. Subsequent LSR to the buccal/mandibular branches was not observed until 9.8 mA, indicating good decompression. The patient tolerated the procedure well with complete resolution of her symptoms and remains spasm-free as of three months post-procedure without a hearing deficit. The 30-degree endoscope enabled visualization of pathology that was not easily seen at 0-degree. Additionally, LSR indicated persistent nerve compression following root entry zone decompression. Subsequent distal decompression resulted in greater LSR reduction. This case report suggests that MVD for HFS may yield better results with both proximal and distal decompression of the seventh nerve, and this type of decompression can benefit from endoscopic visualization.

Highlights

Hemifacial spasm (HFS) is a condition of unilateral involuntary, spasmodic contractions of the muscles innervated by the facial nerve
These limitations can be overcome during the microvascular decompression (MVD) procedure by using an endoscope which provides enhanced visualization and the ability to see around corners to more accurately assess the completeness of decompression [7, 9,10,11,12]
This case report demonstrates the use of the 30-degree endoscope enabling visualization of pathology that otherwise was not seen at 0-degree, both at the root entry zone and at the distal portion of the nerve

Summary

Introduction

Hemifacial spasm (HFS) is a condition of unilateral involuntary, spasmodic contractions of the muscles innervated by the facial nerve. Neurovascular decompression can be assessed visually and by way of monitoring lateral spread response (LSR) This case report highlights how the endoscopic MVD approach and LSR can be used to optimize the neurosurgical management of patients with HFS. A 30-degree endoscope was directed medially and inferiorly and neurovascular compression at the root entry zone of the facial nerve was identified (Figure 2) This was decompressed with three pieces of shredded polytetrafluorethylene (PTFE). While this was an improvement from baseline, significant LSR was still present. The patient tolerated the procedure well without complications and had complete resolution of her symptoms

Discussion

Findings

Conclusions

Disclosures