How is hypoglossal-facial anastomosis performed in facial nerve repair?

Updated: Nov 28, 2018
  • Author: Tang Ho, MD, MSc; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

A parotidectomy-type incision is made. The facial nerve is identified as it exits the stylomastoid foramen and is followed to just beyond the pes anserinus. It is sharply transected where it exits the stylomastoid foramen.

The hypoglossal nerve is then isolated in the neck. It may be identified by following the posterior belly of the digastric toward the hyoid bone. The hypoglossal nerve passes lateral to the carotid artery and medial to the internal jugular vein. The nerve may then be followed distally to gain the maximum length for anastomosis. The descendens hypoglossi is usually transected to aid in mobilization and length.

In the case of an end-to-end anastomosis, the hypoglossal nerve is transected distally and brought to meet the facial nerve by passing it either medial or lateral to the digastric muscle. The grafting of the nerve ends proceeds as previously discussed.

If a jump graft is performed, identification and transection of the facial nerve proceed in the same manner. In this case, an appropriate length of great auricular nerve is then harvested. The hypoglossal nerve is then identified, including the descendens branch. The nerve is partially incised in a beveled fashion (most authors recommending cutting one third to one half the way across). The great auricular nerve graft is anastomosed to the proximal portion of the beveled cut. The other end is grafted to the distal end of the facial nerve in a typical fashion.

Another option for preserving tongue function is the split hypoglossal nerve graft. In this technique, the hypoglossal nerve is split and dissected back to obtain a length that can be anastomosed to the facial nerve, which means that only 1 anastomosis would be required. However, given that the hypoglossal nerve also exhibits a lack of spatial orientation, with the nerve fibers interwoven randomly, some consider this approach flawed concept because splitting of the nerve any significant distance would cause significant denervation of the tongue.


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