gms | German Medical Science

Patients with total paralysis of the facial nerve have serious functional, psychic and cosmetic impairments. The preservation and repair of the facial nerve remains a major challenge in skull base and mastoid surgery.

Surgical treatment may involve either minor operations such as tarsoraphy, the use of springs and weights, or larger ones, such as facial nerve grafting, anastomosis of the facial to the hypoglossal nerve, muscle transfers, or transpositions.

Transposition of the facial nerve and end-to-end anastomosis to the hypoglossal nerve was a popular and effective technique with satisfying results. The complete transection of the hypoglossal nerve results in homolateral paralysis and an atrophy of the ipsilateral tongue, which produces additional problems in those patients whose facial functions are not normal. According to Hammerschlag [Ref. 1] 45% of patients with such an operation reported speech and swallowing disorders.

In 1997, articles by Darouzet [Ref. 2] and Atlas [Ref. 3] described a new technique for hypoglossal-facial anastomosis. The first author presented four patients and the second author three patients who, among others, were operated on using a new technique. It consists of hemi-hypoglosso-facial anastomosis with rerouting (mobilisation and transposition) of the intratemporal part of the facial nerve without using a nerve graft. With this technique, the sequelae of hemi-lingual atrophy and paralysis (problems with articulation, mastication and deglutition) are reduced or even abolished. It is also possible to achieve a satisfying result with regard to facial functions. Until now, few reports have been published presenting this new modification [Ref. 4], [Ref. 5], [Ref. 6].

A retroauricular incision is made, which is continued to the hyoid bone along the sternocleidomastoid muscle. The hypoglossal nerve is located in the neck under the digastric muscle. We also mobilise the facial nerve at the exit from the stylomastoid foramen to the level of the pes anserinus in the parotid gland.

The mastoidectomy is performed as a canal wall-up procedure; the facial nerve is identified and mobilised in its vertical portion. The facial nerve is cut at its second genu, at the level where it leaves the tympanic cavity and where its horizontal part lies. At the level of the digastric ridge, at the tip of the mastoid, the mobilisation is difficult because of bleeding from the stylomastoid artery and we have to remain under the facial nerve to dissect it from surrounding tissue. After the nerve is mobilised and transposed, the hemostasis should be made. The facial nerve is brought under the digastric muscle, which we believe gives additional protection to the anastomosis. The hypoglossal nerve is cut to half of its diameter before it divides to ansa n. hypoglossi. The facial nerve is sutured to the proximal part of the hypoglossal nerve incision with 10.0 nylon sutures (Figure 1 [Fig. 1]). The anastomosis should be done tensionless. We also apply 0.5 ml of fibrin glue to the region of the anastomosis.

Our results showed two patients with a House-Brackmann (HB) [Ref. 7] grade of III, one with grade IV, one with grade V and we had a complete failure in one patient. All of them were operated on in a time interval of 8 to 13 months after the facial nerve injury. In three patients the facial nerve was injured during acoustic nerve surgery and two had severe head trauma with fracture of the skull base. Their age was between 24 and 67 years. In all operated patients, the complete denervation of the facial musculature was proven by electromyography.

Results of facial nerve repair surgery are dependent on the duration of the paralysis and thus the state of the facial nerve and mimic musculature. The nerve repair should be done within a period of one year, when we might be sure of some functional results.

The results after facial nerve repair begin to appear after six months, but the definitive result can be observed after two or even from 3–5 years [Ref. 8].

Darouzet [Ref. 4] reported five patients with House-Brackmann grade III and one with the grade IV. With the end-to-end technique, he had 32% grade III patients, 61% grade IV patients and 7% grade V patients.

Although our patient group is small, we observe that facial nerve reinervation succeeded better in younger patients. The failure in elderly patient could be explained by graft separation and infection.

The results of a new surgical technique are comparable to an end-to-end procedure. The most important benefit is reduced morbidity regarding the tongue’s functioning. All our patients have normal tongue mobility, without any difficulties in swallowing or atrophies of the tongue.

The new technique is perhaps more demanding and time consuming, but it is justified by reducing the morbidity of the tongue if we compare it with end-to-end hypoglossal-facial anastomosis. Further use of side-to-end hypoglossal-facial anastomosis via transposition of the intratemporal facial nerve is needed for better evaluation of the technique.