Comparison of Hemihypoglossal Nerve versus Masseteric Nerve Transpositions in the Rehabilitation of Short-Term Facial Paralysis Using the Facial Clima Evaluating System :

This study assesses the ability of the masseter motor nerve-innervated microneurovascular muscle transfer to produce an effective smile in adult patients with bilateral and unilateral facial paralysis. The operation consists of a one-stage microneurovascular transfer of a portion of the gracilis muscle that is innervated with the masseter motor nerve. The muscle is inserted into the cheek and attached to the mouth to produce a smile. The outcomes assessed were the amount of movement of the transferred muscle; the aesthetic quality of the smile; the control, use, and spontaneity of the smile; and the functional effects on eating, drinking, and speech. The study included 27 patients aged 16 to 61 years who received 45 muscle transfers. All 45 muscle transfers developed movement. The commissure movement averaged 13.0 +/- 4.7 mm at an angle of 47 +/- 15 degrees above the horizontal, and the mid upper lip movement averaged 8.3 +/- 3.0 mm at 42 +/- 17 degrees. Age did not affect the amount of movement. Patients older than 50 years had the same amount of movement as patients younger than 26 years (p = 0.605). Ninety-six percent of patients were satisfied with their smile. A spontaneous smile, the ability to smile without thinking about it, occurred routinely in 59 percent and occasionally in 29 percent of patients. Eighty-five percent of patients learned to smile without biting. Age did not affect the degree of spontaneity of smiling or the patient's ability to smile without biting.

The microneurovascular transfer of a free muscle transplant is the procedure of choice for facial animation in a child with facial paralysis. One of the critical factors of this procedure is the selection of a motor nerve to innervate the transplanted muscle. From 1989 to 1999, 166 free segmental gracilis muscle transfers were performed in 121 children for facial animation. The cross-face nerve graft was used in 70 procedures (cross-face nerve graft group) to innervate the muscle by branches of the seventh nerve for the normal side. The ipsilateral masseteric nerve was used in 94 procedures (50 patients, masseter group) and the ipsilateral accessory nerve was used in two procedures (one patient). To compare the operative procedures between the first two groups, all charts were reviewed. The extent of oral commissure movement was determined by measurements taken from the tragion to the oral commissure, both at rest and with full smile. In the cross-face nerve graft group (n = 20), the extents were measured on both the normal side and the reconstructed side; in the masseter group (n = 16), they were measured on the left and right sides. No significant difference was found between the two groups (p < 0.05) for the mean age at the time of muscle transplantation, for the total operation time for muscle transplantation, and for the length of the muscle used or for the fraction of circumference of the segment of gracilis muscle used. Although the operative variables were similar between two groups, the muscle excursion differed. Excursion in the cross-face nerve graft group was less than that on the right (p = 0.0006) or left (p = 0.0000) in the masseter group. It was also less than on the normal side (p = 0.0000) of the cross-face nerve graft group. Also, there was no significant difference between the left and right sides within the masseter group (p < 0.05). Furthermore, the extent of oral commissure movement in the masseter group was similar to that of the normal side in the cross-face nerve graft group (p = 0.35, p = 0.61). These results indicate that segmental gracilis muscle transplantation using the motor nerve to the masseter nerve for facial animation in children is a very reproducible operation and provides a commissure excursion in the range of normal.

This article describes facial reanimation using the transfer of the trigeminal motor nerve branch of the masseter muscle (masseter nerve) to the facial nerve (masseter-to-facial nerve transfer).