Anterior belly of digastric muscle transfer: a useful technique in head and neck surgery

Permanent loss of the marginal mandibular branch of the facial nerve (MMBFN) may result from an inadvertent injury or an intentional sacrifice during tumor resection. This may occur in isolation or as a part of total facial nerve palsy. The loss of the MMBFN results in paralysis of the depressors of the ipsilateral lower lip with troublesome cosmetic and functional deficits.

A series of 14 patients with permanent loss of the MMBFN during resection of head and neck tumors were treated with the anterior belly of digastric muscle transfer (ABDMT). The loss of the MMBFN occurred in isolation in five patients and formed a part of total facial nerve palsy in nine. Immediate reconstruction was performed on nine patients, and it was done as a secondary procedure in the remainder. Two patients in the latter group had prior facial reanimation, although the paralyzed lower lip was not reconstructed.

The average follow-up period was 23.2 (range, 3-48) months. Satisfactory results were achieved in all of the patients, although revision of the ABDMT was required in one patient.

ABDMT is a simple and reliable reconstructive technique for restoring the depressor function of the lower lip resulting from MMBFN palsy. It is the treatment of choice during primary extirpative surgery for head and neck tumors when the MMBFN requires sacrifice for tumor clearance or is inadvertently injured. The reconstructive options for MMBFN palsy, particularly in the absence of the anterior belly of digastric muscle, are discussed.