65 Hypoglossal-to-Facial Nerve Transfer with Parotid Release for Rehabilitation of the Paralyzed Face in Vestibular Schwannoma

10.1055/b-0039-169219

65 Hypoglossal-to-Facial Nerve Transfer with Parotid Release for Rehabilitation of the Paralyzed Face in Vestibular Schwannoma

David R. Friedmann and J. Thomas Roland Jr.

65.1 Introduction

Facial reanimation after paralysis is an important tool in the armamentarium of any skull base surgical practice and may be carried out by neurotologists, neurosurgeons, and microvascular-trained head and neck or facial plastic surgeons. A comprehensive facial nerve center often encompasses some or all of these members to assist in selecting the best treatment for a given patient. In cases where possible, an end-to-end anastomosis or interposition graft bridging the two ends of the facial nerve is preferred for dynamic reanimation.

When the proximal facial nerve is not available for use, the distal facial nerve may be anastomosed to a separate motor nerve, traditionally the hypoglossal nerve and more recently the masseteric branch of the trigeminal nerve (see Chapter 66), with the goals of providing facial tone, symmetry, and volitional dynamic movement. Our center has modified prior techniques of hypoglossal-to-facial (12–7) nerve transfer through a parotid release maneuver to facilitate a single tension-free anastomosis with minimal or no tongue morbidity.

65.2 History and Overview of the Procedure

Hypoglossal-to-facial anastomosis was first performed in 1901 by Korte in end-to-end fashion.s. Literatur As this report indicated, transection of the hypoglossal nerve to allow for end-to-end anastomosis results in ipsilateral paralysis and atrophy of the tongue musculature, which can lead to dysphagia and dysarthria. This can be of even greater functional consequence in patients with preexisting facial weakness and/or lower cranial neuropathies as in neurofibromatosis type 2 patients. Subsequently, May et al introduced a modification involving end-to-side coaptation using an interposition graft, hence preserving ipsilateral tongue function.s. Literatur This technique has also been termed “jump interposition graft hypoglossal-facial anastomosis” (JIGFA). Subsequent reports of a split hypoglossal-facial nerve anastomosis have been published, where a part of the hypoglossal nerve is left in its anatomic position with subsequent end-to-end anastomosis.

In 1997, Atlas and Sawamura independently reported on a facial nerve transposition technique in which the facial nerve is freed from its intratemporal location and transposed and anastomosed to the hypoglossal nerve in an end-to-side fashion without use of an interposition graft.s. Literatur ^, s. Literatur In 2006, our group first published our modification of the facial nerve transposition technique by including a parotid release maneuver to ensure consistent tension-free anastomoses.s. Literatur In a subsequent publication, Slattery et al and members of the House Clinic described a similar technique that they termed a hypoglossal-to-facial anastomosis “swingdown” technique.s. Literatur

65.3 Advantages and Limitations

This technique allows for a single tension-free anastomosis without associated tongue morbidity. The JIGFA technique also spares tongue morbidity, but still requires harvest of a separate nerve jump graft with associated donor site morbidity, and also incorporates two anastomotic sites. The parotid release maneuver, to aid in direct anastomosis, takes advantage of the intratemporal facial nerve in the temporal bone.

Primary facial nerve pathology involving the tympanic or mastoid segments of the facial nerve (i.e., schwannoma, glomus faciale, hemangioma) precludes its use for this technique. Additionally, the parotid release maneuver bears the risk of postoperative sialocele, which often resolves with conservative measures. Finally, the released portion of the parotid gland may protrude in the preauricular region, but this generally resolves during the postoperative period.

65.4 Patient Evaluation and Selection

This procedure is appropriate for patients with intact facial musculature and an intact distal course of the facial nerve. Pathology of the tympanic or mastoid segments of the facial nerve precludes use of the parotid release technique, but may still be amenable to 12–7 anastomosis with an interposition graft of sufficient length.

Optimally, this procedure is performed as early as possible after nerve transection and not beyond 12 to 16 months because of concern for atrophy of facial musculature and loss of motor end plates prohibiting reinnervation. In cases where facial nerve sacrifice is anticipated or preoperative facial function is poor, the reanimation procedure may be performed in the same operative procedure as tumor resection. In our experience, if no movement is seen 6 months after original vestibular schwannoma resection and the facial nerve is confidently anatomically intact, there is a role for electromyography to confirm the absence of reinnervation potentials. If none are present, the patient may be offered a dynamic facial reanimation procedure.

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