Abstract
Background
Several methods of neural rehabilitation for facial paralysis using 12-7 transfers have been described. The purpose of this study is to report on a series for dynamic reinnervation of the paralyzed face by using a split 12-7 nerve transposition. The goals of this procedure are to minimize tongue morbidity and to provide good facial reinnervation.
Methods
Prospective case series. Melolabial crease discursion, overall facial movement, and degree of tongue atrophy and mobility were recorded.
Results
Thirteen patients underwent facial reanimation using a split hypoglossal-facial nerve transfer with postoperative follow-up to 58 months (range, 6–58 months). All patients achieved excellent rest symmetry and facial tone. Of 13 patients, 10 had measurable coordinated movement and discursion of their melolabial crease. Of 13 patients, 12 had mild to moderate ipsilateral tongue atrophy. The mean time to onset of visible reinnervation was 3 months.
Conclusion
Split hypoglossal-facial nerve transposition provides good rehabilitation of facial nerve paralysis with reduced lingual morbidity. Long-term rest symmetry and potential learned movement can be achieved. This technique may provide a favorable alternative to the traditional method of complete hypoglossal sacrifice or jump grafting.
1
Introduction
Neural rehabilitation of facial paralysis typically involves epineural neurorrhaphy from a donor motor nerve. The most popular of the potential options has been the ipsilateral hypoglossal nerve. The landmark work done by Conley et al describing their 30-year experience highlights the utility and success rate of this operation. Although this procedure is effective in establishing facial tone, rest symmetry, and some movement, it can be associated with significant tongue dysfunction. This results from both the lack of movement and the progressive atrophy seen with denervation of the ipsilateral tongue. Many patients seeking facial rehabilitation do so to avoid the psychological stigmata of appearing to have “had a stroke.” Unfortunately, traditional hypoglossal-facial nerve transfers can lead to patients trading one functional deficit for another. The dysphagia and dysarthria associated with the unilateral sacrifice of the hypoglossal nerve can also appear to be the consequence of a stroke, thereby defeating one of the primary purposes of the operation.
This fundamental limitation of sacrificing one motor nerve for another during hypoglossal-facial nerve transfer has led to the development of numerous adjunctive methods of facial paralysis rehabilitation. Static techniques as well as muscle transfers have been used . Although these provide suspension of the oral commissure and good rest symmetry, they are all means of masking the primary problem of neural loss and motor endplate atrophy. Although useful in the setting of long-standing paralysis, patients who are managed earlier can potentially achieve more natural rest symmetry with neural rehabilitation. The ideal procedure would use a motor nerve that would not result in significant morbidity. The concept of jump grafting has been advocated to achieve this goal . Although there have been reports of success with this procedure, reducing the number of neurorrhaphies from 2 to 1 may provide a theoretical regenerative advantage . Our potential solution to this has been the use of a split hypoglossal-facial nerve neurorrhaphy. Although this technique has been described in several texts, there is a paucity of literature supporting its use . Excepting several case reports, only one clinical series has been reported in the setting of known facial nerve transections, raising some doubts about its applicability in patients with delayed presentations . We report on our series of 13 patients who underwent delayed split hypoglossal-facial nerve neurorrhaphy procedures. This study represents the largest clinical series of this procedure and illustrates its utility for achieving good facial outcomes with acceptable tongue morbidity.
2
Materials and methods
This study is a retrospective review of clinical experience from 2002 to 2008. All patients who underwent a split hypoglossal-facial nerve neurorrhaphy for complete facial nerve paralysis are included. Most (11/13) were followed for a minimum of 6 months before neural rehabilitation procedures were undertaken because the status of the facial nerve and its integrity were uncertain. Preoperative electromyographic studies were done to document the presence of fibrillation potentials and the absence of any polyphasic action potentials, suggesting potential delayed recovery. Postoperatively, patients were followed every 3 months for 2 years, then annually. Follow-up findings of both facial nerve motion and tongue function were noted at each office visit. The facial nerve function was graded using both the House-Brackmann and May grading classifications . This study was approved by the institutional review board (no. 08-220).
2
Materials and methods
This study is a retrospective review of clinical experience from 2002 to 2008. All patients who underwent a split hypoglossal-facial nerve neurorrhaphy for complete facial nerve paralysis are included. Most (11/13) were followed for a minimum of 6 months before neural rehabilitation procedures were undertaken because the status of the facial nerve and its integrity were uncertain. Preoperative electromyographic studies were done to document the presence of fibrillation potentials and the absence of any polyphasic action potentials, suggesting potential delayed recovery. Postoperatively, patients were followed every 3 months for 2 years, then annually. Follow-up findings of both facial nerve motion and tongue function were noted at each office visit. The facial nerve function was graded using both the House-Brackmann and May grading classifications . This study was approved by the institutional review board (no. 08-220).
3
Surgical technique
A modified Blair incision is used to allow identification and isolation of the facial nerve. The inferior limb of the incision is extended anteriorly to allow for dissection of the hypoglossal nerve in the same surgical field. A standard superficial parotidectomy approach is then performed to identify the facial nerve trunk. The lateral lobe of the parotid gland is not removed but retracted anteriorly. The hypoglossal nerve is initially dissected in its path at the point anterior to the posterior belly of the digastric muscle, and then traced both anteriorly and posteriorly. Using an operating microscope, the epineurium of the hypoglossal nerve is then divided linearly along its course parallel to the direction of the fibers using an 11-blade edge to create a short linear neurotomy. Microdissection scissors are used to complete the split procedure. Care is taken to divide the fibers equally. Finally, the anterior release of the superior nerve bundle is performed with microscissors. These fibers are then rotated superiorly to meet the facial nerve stump. An epineural neurorrhaphy is then performed using 9-0 monofilament nonabsorbable sutures. The technique is illustrated in Fig. 1 A to D. Fig. 2 A and Fig. 2 B are representative intraoperative photographs.
4
Results
Postoperative outcomes are shown in Table 1 . The surgery was successfully performed in all 13 patients with no immediate postoperative complications. The range of time from onset of paralysis to surgery was 3 weeks to 30 months. All of the patients in the series were able to achieve rest symmetry of their oral commissure in long-term follow-up. One representative patient, postoperatively, is shown in Figs. 3 A to 4B . All patients achieved a postoperative House-Brackmann score of III to IV and a May classification score of excellent or good (II or III) except for one patient. The mean time to onset of visible neural reinnervation was 3 months with tone returning before dynamic movement. Patients continued to show improvement over a 6-month period to achieve their final outcomes. Of 13 patients, 10 had notable volitional facial movement measured by melolabial crease discursion ranging from 3 to 12 mm. Morbidity to the tongue was assessed by examination of lateral movement and degree of atrophy (classified as none, minimal, moderate, and severe). Of 13 patients, 8 had minimal atrophy, 5 had moderate, and 1 had severe. All patients except the one with severe atrophy had bilateral tongue mobility.
