How is cross-facial nerve graft 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

Several variations of the cross-facial anastomosis have been described. These differ in terms of which donor facial nerve branches are used, how many cross-facial grafts are performed, and the path chosen to pass the graft across the face to the other side.

In each variation of the procedure, a suitable nerve to graft must be chosen. The sural nerve is most commonly used because the length of nerve required to thread across the entire face, particularly if several branches are to be anastomosed, is quite significant. Alternatively, one may perform a single graft, in which case the great auricular nerve may be sufficient.

Dissection is performed first on the paralyzed side to ensure that the distal nerve can be identified. If several branches are to be grafted, the branches may be identified by following the nerve beyond the pes anserinus and identifying the branches within or just beyond the parotid gland. The contralateral normal facial nerve is identified in the standard fashion.

The branches are individually identified. The donors are taken at the distal border of the parotid gland. A nerve stimulator is used to determine the areas innervated by the individual branches, and for each facial region, an attempt is made to find multiple nerve branches supplying a given area. This allows for the sacrifice of 1 branch with preservation of an adequate degree of function for a given anatomic region.

The sural nerve is then harvested and the branches tunneled across the face. This may be performed above and below the lip and through the neck. Passing the nerve across the forehead may have a poorer result because of the lesser blood supply to the graft lying within a relative lack of soft tissue. The nerve graft is sutured to the normal side. The graft may then be sutured to the chosen branch or branches on the paralyzed side.

Another option is to forego the anastomosis on the paralyzed side. A “babysitter” hypoglossal nerve anastomosis may be performed instead. This provides innervation to the paralyzed facial musculature and thereby prevents further degradation of the motor endplates and muscle atrophy as regeneration occurs across the considerable distance necessary for the cross-face graft.

In this situation, the Tinel sign (ie, paresthesias associated with areas of nerve regeneration) is followed across the face for several months, and the patient is returned to the operating room when this sign indicates that regeneration has completely spanned the gap. The grafts are then anastomosed to the paralyzed branches.

A simpler technique uses only the marginal mandibular branch, which is sacrificed and anastomosed to the main branch of the paralyzed nerve in a single setting. Function for each of these cases takes at least 6 months to begin to return. As with the other procedures, synkinesis is expected.


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