Facial Nerve Palsy: Indications and Techniques of Surgical Repair

A peripheral facial nerve palsy may be the consequence of different clinical problems. This chapter will purposely exclude the congenital cases. They are a very particular subset of these palsies and recognize different strategies, including free flaps, the discussion of which goes far beyond the scope of this chapter. Among the facial palsies also we would exclude the Bell’s and the Ramsay Hunt zoster palsies. Especially the last ones are usually more severe, and in selected cases they can attain a surgical indication, but the full range of possible treatments, including botulin toxin, free flaps or boost neurotizations is very variable and difficult to classify. Therefore, object of the treatise will be all the conditions in which the facial nerve may be potentially interrupted, severely scarred or compressed, thus requiring a surgical exploration aimed at repair of the nerve. The conditions encountered are the following:


Injury of the facial nerve at the extracranial level.


Injury of the facial nerve at the intratemporal level (skull base fracture and special tumours).


Iatrogenic injury of the facial nerve in the cerebellopontine angle: under these conditions usually the proximal stump of the nerve is not available.


Special cases, namely, nuclear peripheral nerve palsies at the level of the brainstem, are a very rare occurrence and the correct treatment is uncertain.



21.1 Introduction


Generally speaking, the ideal method to restore the function of the facial muscles is a facio-facial suture, when suitable proximal and distal stumps of the facial nerve are at hand. The patients submitted to this kind of repair show the best aesthetical and functional results. They may reach a good to excellent House–Brackmann grade (I, II, or III) depending on several factors (age, timing of repair, distance from the brainstem, direct suture vs. graft) and their recovery is the only one potentially able to show a static, voluntary, and emotional response of the face. 1,​ 2,​ 3,​ 4


In the vast majority of the facial nerve cases, however, the proximal stump is not available, usually because it is lost at the brainstem, as it happens after complex skull base surgery.


Under these conditions, the technique more frequently used is a nerve transfer with a donor nerve different from the facial nerve.


All the possible options will be critically analyzed in terms of choice of the donor and, for each donor nerve, the different nuances of repair will be elucidated.


Any subheading will report the number of operated cases; this is not to discuss in detail the clinic of each patient treated, but just to give an idea of the distribution of this pathology through a 20-year period in a dedicated neurosurgical setting.


21.2 Surgical techniques and Results


21.2.1 Extracranial nerve repair (10 cases)


An injury in the extracranial portion of the facial nerve must be repaired with a facial-to-facial approach. The only exception to repair is represented by the malignant tumours of the face, where the necessity of full clearance may discourage the preservation of useful distal stumps, and when the recovery is strongly jeopardized by local factors (severe scarring, radiotherapy).


In these cases, one may recur to a secondary dynamic temporalis transfer, for example, the one popularized by D. Labbè. 5


Excluding tumours in the face, we are usually dealing with stab or knife wounds, iatrogenic injuries, and, rarely, gunshot injuries ( ▶ Fig. 21.1).



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Fig. 21.1 Gunshot injury to the face—birdshots—attempt at suicide.


In these cases, the exploration and retrieval of the injured stumps may be a painstaking task, but very often it is a matter of ability and luck directly depending on the surgeon’s experience.


The authors strongly make a plea for those cases, rare, of stab wounds in the region of the tragal pointer, where a proximal stump is no longer present.


Due to the possibility that different specialists may be involved in such cases, there is a consistent risk of resorting to an extrafacial nerve transfer, like the hypoglossal, to treat these lesions. One must always bear in mind that the best results come from a facio-facial nerve repair.


Therefore, for these cases, the correct solution is only one: a dissection of the temporal bone to reach a good proximal stump followed by a graft repair. Any other solution would unduly lower the quality of the recovery.


21.2.2 Intracranial repair with proximal stump available (3 Cases)


In course of skull base approaches (transotic, infratemporal type B, translabyrinthine, geniculate ganglion tumours), the surgeon may be in the condition of a straightforward repair of the facial nerve. Either with a direct suture or with a graft, the nerve may be “suspended in the air,” with the possibility of mobilization of the coapted stumps. If there is enough space, the author recommends protecting the suture with a sleeve of vein covered with fibrin glue and containing the two extremities sutured with Nylon 9–0.


From time to time, in course of cerebellopontine angle (CPA) tumors operated by the retrosigmoid route, the proximal stump of the facial nerve may be localized at the brainstem, but the distal stump into the IAC (internal auditory canal) is absent. Under these circumstances, a sural nerve graft may be sutured, in a second stage, to the distal extracranial facial nerve. This procedure is, for the above-mentioned reasons, preferable to a transfer done with a different nerve. This intracranial–extracranial repair is a very rare occurrence, but it gives good results and it is worth doing (Dott’s technique). 6


21.2.3 Nerve Transfers When the Proximal Stump Is Unavailable (58 cases)


The possible donors historically used 7,​ 8,​ 9,​ 10 to supply a facial nerve without proximal stump are the following:




  • Facio-facial cross-face (4 cases).



  • Accessory nerve spinofacial anastomosis (1 case).



  • Hypoglossal nerve (42 cases: 28 jump-graft technique + 14 intratemporal translocation).



  • Masseteric nerve (9 cases).



  • Mixed neurotizations (2 cases).


As a matter of fact only the last three are used nowadays.


The facio-facial cross-face is very seldom planned, while the spinofacial is only anecdotical and is no longer used.


Facio-facial Cross-face (4 Cases)


This was a potentially very promising technique, 11 because of the theoretical possibility of an emotional response offered by the contralateral sound face.


A redundant branch of the normal facial nerve, usually found in the nasolabial fold area, acts as a donor. A sural nerve graft is then passed subcutaneously across the upper lip, if possible using a bifurcation to cover the two main branches to the orbicularis of the eye and of the mouth.


The problem with this technique, which gives very poor results, is manifold. The author has seen 0/4 useful results and the same disappointing results are also shared by many of the author’s colleagues committed to facial nerve surgery.


In spite of an accurate search, it is very difficult to find a powerful donor with enough axons to cover the whole contralateral paralyzed face. The relative length of the graft, in our cases ranging from 12 to 15 cm, is probably another important obstacle, and so it is the time interval between injury and referral, often too long. To overcome this aspect, a variant of the technique has been forwarded by Terzis, 12 and is called “the babysitting technique.” It consists of a two-stage procedure: as a first step, an hypoglosso-facial anastomosis is performed, and a graft, sutured to a donor branch of the contralateral normal facial nerve, is left loose in the face, in the vicinity of the recipient. Approximately 1 year later, after the recovery warranted by the hypoglossal nerve, the recipient facial nerve is cut and re-sutured to the distal stump of the graft formerly left free and innervated by the contralateral normal facial nerve branch.


This last technique, however, has several limitations: one is the difficulty to move around the scar of the first surgery without damaging the graft and the recipient branches, and the second concerns the opportunity to abort a favorable reinnervation in favor of an unknown result which, far from being guaranteed, also has never been convincingly demonstrated.


Presently we do not ordinarily plan a facio-facial cross-face, but still we like very much the theoretical possibilities of this procedure. In very early referrals (few days after a facial nerve section), after accurate informed consent, this treatment is considered. Early referrals are always very rare, partly for a lack of coordination among the neurosurgical centers but more often because, in many patients, the anatomical preservation of part or of the entire facial nerve discourages an early reinnervation, entrusting these patients to the physical therapy and to an endless sequence of electromyographies.


Spino-facial Anastomosis (1 Case)


As to the authors’ experience, this technique works, at least in the only case that the authors had the possibility to operate about 20 years ago. This was a patient with an acoustic tumour who had been formerly operated in the tongue area, with a partial damage to the hypoglossal nerve, while the use of the masseteric nerve was not yet popular.


The technique gives a satisfactory result concerning the resting tone and symmetry. 13 At activation of the shoulder, the face dyskinesias are not much disfiguring in themselves, being not so different from the first cases of hypoglosso-facial anastomosis, but the combination with the provoking movement of the shoulder appears rather awkward. In choosing this type of nerve transfer, it is paramount to interrupt only a portion of the accessory nerve, lest the trapezius muscle be paralyzed.


Hypoglossal-Facial Anastomosis (42 Cases)


When the proximal stump is lost. this is by far the oldest and most popular technique ever used to reinnervate the facial nerve. 14,​ 15,​ 16 The literature is rich of articles dealing with this issue and this because the surgical technique has evolved with time. 17,​ 18,​ 19,​ 20,​ 21,​ 22


The main debates are related to the quantity of axons useful for reinnervation (i.e., the percentage of donor nerve that should be interrupted) and the need for a graft. In the last 15 years, a few authors dedicated their attention to avoid the grafting procedure, analyzing different techniques of intratemporal translocation and rerouting of the recipient facial nerve. 23,​ 24,​ 25


At the beginning, the entire hypoglossal nerve was cut and anastomosed to the denervated facial nerve. This entailed a heavy impairment of tongue function which in turn added to the difficulty in chewing due to the facial nerve palsy. Anatomically this is a nonsense, because the square section of the facial nerve is half of the hypoglossal nerve. Then, in turn, it means an excess of motor axons that, far from being necessary to reanimate the facial muscles, provoke disfiguring mass movements in the reanimated muscles.


A successful and modern evolution of this transfer has been prompted by M. May, 26 who introduced and popularized the so-called jump-graft procedure.


21.2.4 Hypoglossal-Facial Jump Graft (28 Patients)


This is a nerve transfer vehiculating via a graft a few axons of the hypoglossal nerve, taken after the emission of the descending branch (to be sure to select powerful motor axons) and directed to the main trunk of the facial nerve identified at the tragal pointer, which acts as recipient ( ▶ Fig. 21.2).



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Fig. 21.2 Hypoglossal-facial jump graft with the greater auricular nerve.


Practically, through a single incision going from the helix to the angle of the mandible, one first identifies the facial nerve at the exit of the stylomastoid foramen checking its functionality. Then one goes lateral and below the mandible where the digastric muscle is found, elevated, and retracted medially with a stitch passed in the tendon. This helps isolate the hypoglossal nerve while crossing the external carotid artery. Normally there is no need to interrupt any arterial branch, while some secondary lingual vein can be ligated to gain the access.


The hypoglossal nerve is stimulated after the takeoff of the descending branch and the epineurium is opened. About one-fourth of the nerve is sectioned. A V-shaped small area distal to the interrupted fascicles is removed and a space is created to lodge the graft, cut slantingly and ready to receive the hypoglossal donor axons. The graft is about 5 cm long and can be either found locally, namely, the greater auricular nerve (GAN) of the vagus, or taken from the sural nerve. There is no difference in terms of results between the two options, but the first is preferable, to have the whole surgery done with only one incision.


To harvest a good length of the GAN, some more experience is required. One must pay attention from the very beginning of the incision, because the GAN could be inadvertently damaged.


The authors have operated 28 patients with this technique and had very good results ( ▶ Fig. 21.3). Among them, 25 attained a useful HB score (usually III H-B, due to the obvious dyskinesias). Dyskinesias are normally tolerated although, from time to time, they can be disfiguring and require the use of the botulinum toxin. The 3 patients who did not have results, however, were operated later than 18 months after the facial nerve palsy. This time limit, according to our experience, should not be overcome.



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Fig. 21.3 Result of an hypoglossal jump graft—good reanimation despite advanced age.


The early signs of a positive result (a good recovery of symmetry at rest) start on average at about 7 to 8 months after surgery. The eye must be treated separately, with a gold weight or, better, a platinum chain weight, or using a temporalis muscle sling 27 ( ▶ Fig. 21.4).



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Fig. 21.4 Palpebral sling pedicled from the temporalis muscle.

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Nov 5, 2018 | Posted by in NEUROSURGERY | Comments Off on Facial Nerve Palsy: Indications and Techniques of Surgical Repair

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