Endoscope-Assisted Microvascular Decompression in Hemifacial Spasm: 2-Dimensional Operative Video

Abstract

INDICATIONS: CORRIDOR AND LIMITS OF EXPOSURE: This video demonstrates our endoscope-assisted microvascular decompression (MVD) technique in hemifacial spasm. A 2-cm lower retrosigmoid approach is used to reach the facial nerve exit zone. The additional use of endoscopy serves to overcome the microscopes linear axis of view on the compression site. ANATOMIC ESSENTIALS: NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: A neurovascular conflict in the facial nerve exit zone is to be identified on CISS-MRI. A CT scan helps assessing the approach. Acoustic evoked potentials and facial nerve neuromonitoring including lateral spreads are required. 1 ESSENTIAL STEPS OF THE PROCEDURE: The patient is positioned supine with 45° head rotation to the contralateral side. In addition, the operating table is tilted 30° to facilitate optimal cerebellar retraction by gravity avoiding the need for cerebellar spatula. The dura is incised parallel to the sigmoid sinus. With the operating microscope, the arachnoid is dissected exposing the vestibulocochlear nerve and the lower cranial nerves. The lower cranial nerve group is exposed up to the exit from the brain stem, enabling a subfloccular approach to the facial nerve exit zone. The endoscope is used to inspect the facial nerve and to identify the compressing vessel. Microscopically, the vessel is mobilized and the nerve decompressed by shredded Teflon. 2 PITFALLS/AVOIDANCE OF COMPLICATIONS: Jugular vein compression by excessive head rotation must be avoided. Teflon placed directly onto the nerve can cause spasms itself. Opened mastoid cells are carefully sealed. VARIANTS AND INDICATIONS FOR THEIR USE: Transposition is favored over interposition. Besides shredded Teflon, a Teflon-Bridge or Teflon-Sling can be placed. 3-5 The patient consented to the procedure and to the publication of her image.