Endoscopic Microvascular Decompression for Hemifacial Spasm

Abstract

Introduction and objective: Hemifacial spasm (HFS) is a condition, characterized by painless, involuntary unilateral tonic or clonic contractions of the facial muscles innervated by the ipsilateral facial nerve. HFS starts with contractions in the orbicularis oculi muscle with subsequent eyelid closure and/or eyebrow elevation, but may spread to involve muscles of the frontalis, platysma, and orbicularis oris muscles. Microvascular decompression (MVD) is reliable and accepted surgical treatment for HFS. MVD is the standard surgical technique now for HFS treatment with long-term success rates.

Materials and methods: We performed fully endoscopic MVD technique for 1 patient with HFS (a 83-year-old female) at our institution. HFS was diagnosed based on the clinical history and presentation, a neurologic examination, and additional imaging findings. Respectively, the durations of HFS were 3 years, respectively. The patient had been previously treated with repeated botulinum toxin injections. Preoperative evaluation was done with magnetic resonance imaging; three-dimensional computed tomography fusion images examinations had identified the anterior inferior cerebellar artery (AICA) as the offending vessel in this patient.

Results: The patient with HFS was treated by fully endoscopic MVD technique. The AICA, which had been identified as the offending vessel by preoperative magnetic resonance imaging, was successfully decompressed. No surgery-related complications occurred and had excellent outcomes with the complete resolution of HFS immediately after the operation.

Conclusions: Endoscopic surgery can provide a more panoramic surgical view than conventional microscopic surgery. Fully endoscopic MVD is both safe and effective in the treatment of HFS. This method minimizes the risks of brain retraction and extensive dissection often required for microscopic exposure. Endoscopic MVD is safe and has advantage over microscope in terms of visualization of structure, identification of neurovascular conflict, but it has a learning curve and technically challenging.

Keywords: Endoscope; facial nerve root exit zone; hemifacial spasm; microvascular decompression.

Figure 1

Three dimensional computed tomography brain showing neuro vascular conflict Facial nerve compressed by anterior inferior cerebellar artery

Figure 2

(a) operative room setup. (b) Placement of the endoscope A, the suction C and dissector B should be arranged in a triangle to avoid clashing of instruments

Figure 3

Anatomical landmarks: A: Tip of mastoid process. B and D: Course of transverse sinus. C and D: course of sigmoid sinus

Figure 4

(a) Endoscopic view of craniectomy for E-microvascular decompression of the facial nerve. The dura mater has been opened and reflected toward the sigmoid sinus. (b) Placement of the endoscope 12 o'clock (point A), microinstrument at 5 o'clock (B) and suction at 7 o'clock (C)

Figure 5

Fully endoscopic procedures. (a-c) The acousticofacial bundle is visualized, and the facial nerve and offending vessels were identified. (d and e) Right anterior inferior cerebellar artery is dissected from the root exit zone of the right facial nerve (cranial nerve 7) under the endoscopic view. Neurovascular conflict

Figure 6

(a and b) Intraoperative photograph showing transposition of vessel (anterior inferior cerebellar artery) with Teflon loop and sticked to the petrosal dura mater with fibrin glue. Petrosal dura mater. (c) A final survey surgery using a 30° endoscope was conducted to evaluate the adequacy of the decompression. Teflon pledget (black arrow) is placed between the root exit zone of cranial nerve 7 and the anterior inferior cerebellar artery under the endoscopic view

Figure 7

(a) Small incision and craniotomy with plate. (b) Small incision after closure