Facial Nerve Reconstruction Using a Split Hypoglossal Nerve with Preservation of Tongue Function

A prospective study was conducted on patients suffering from complete facial nerve injury in order to determine whether, with the use of a split hypoglossal nerve, reconstruction of the facial nerve with preservation of tongue function is possible.

The study was conducted on 13 patients. Elapsed time since injury ranged from 1 to 2 years. Responsible mechanisms included iatrogenic injury after the removal of an acoustic neurinoma or trauma. The facial nerve was sectioned at the stylomastoid foramen. The hypoglossal nerve was split longitudinally, with one portion serving for anastomosis. Intraoperative hypoglossal nerve response was measured by recording the compound muscle action potential from the tongue muscle. Each half of the split hypoglossal nerve was stimulated electrically and muscle contraction of the tongue was recorded. The half that showed the least response was selected for anastomosis to the facial nerve. The facial nerve was transected at the stylomastoid foramen and direct anastomosis with one part of the previously split hypoglossal nerve was carried out. The benefits of this procedure are that hypoglossal function is preserved and axonal regrowth follows for the facial nerve.

To analyze the results, the House-Brackman grading system, composed of six grades, was used. Twelve patients in the study were graded VI—with total paralysis—and one was graded V before surgery. After split hypoglossal-facial nerve anastomosis, two of the 13 patients showed mild dysfunction (grade II), seven showed moderate dysfunction (grade III), three showed moderately severe dysfunction (grade IV), and one showed severe dysfunction (grade V).

Microsurgical facial nerve reconstruction using a split hypoglossal nerve results in functional facial nerve improvement with the preservation of tongue function.