[THE EMBRYOLOGY AND ANATOMY OF THE FACIAL NERVE CANAL AND THE FACIAL NERVE].
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Reinnervation of the paralyzed hemiface with a cross-facial nerve graft (CFNG) required division of facial nerve branches on the normal hemiface to serve as axon donors. There is therefore concern about whether any impairment of normal hemiface motion occurs in the postoperative period. To minimize the likelihood of donor-side impairment, donor branches are chosen from the bucco-zygomatic region which was extensive cross branching, as opposed to be the single temporal or marginal mandibular branches. This study chose to determine quantitatively if this practice does, in fact, adversely affect the normal side hemiface motion governed by these branches, viz., eye closure, pucker, and smile. Since surgical procedures near the facial nerve (such as superficial parotidectomy) may leave the patient with transient facial weakness, even in the absence of nerve transection, the hypothesis was that hemiface motion would be impaired on the donor side during the early postoperative period (first month) secondary to edema and/or neuropraxia. However, based on the clinical observation that donor-side facial motion is not demonstrably impaired late after surgery, a further hypothesis was that any early facial motion is not demonstrably impaired late after surgery, a further hypothesis was that any early facial motion impairment would return to normal by 3 months postoperatively. Seven patients underwent sural CFNG as a primary or secondary component of their facial animation procedure. Their facial motion was quantified preoperatively and in serial postoperative examinations using the Maximal Static Response Assay (MSRA) of facial motion. Careful selection of redundant bucco-zygomatic branches of the facial nerve on the normal side for CFNG did not ultimately ( > or = 3 months postoperative) impair the important motions of eye closure, smile, or pucker. Early postoperative ( < or = 1 month) weakness of the smile was seen on both X and Y axes, indicating that both the risorius and zygomatic muscles were transiently weakened. The ability to elevate the lower eyelid was unaffected at any postoperative time point. Movement of the normal hemiface did not appear to be permanently affected by CFNG when a careful choice of redundant bucco-zygomatic donor branches was made.
Methods of monitoring the facial nerve during posterior fossa surgery continue to evolve. In an effort to predict acute and final facial nerve function following acoustic neuroma resection, the lowest current applied to the facial nerve at the brainstem necessary to elicit facial muscle response was measured using strain gauge and electromyographic facial nerve monitors. A retrospective analysis of 121 patients who had undergone acoustic neuroma surgery was performed. Sixty-five patients had intraoperative facial nerve monitoring and 44 had sufficient data for inclusion in this study. The acute and final facial nerve functions, according to the House-Brackmann classification, were assessed with regard to intraoperative stimulation-current thresholds. Nineteen of 20 patients who required 0.10 mA or less to elicit a facial muscle response had a House-Brackmann grade I facial nerve outcome. The upper limit of the 95% confidence interval of stimulation threshold for patients with a final grade I facial nerve function is 0.17 mA. All of the patients in this study, with stimulation thresholds ranging up to 0.84 mA, had a final grade III or better result. A poor outcome in our series, a final grade III facial nerve function, is best predicted by a poor acute result, specifically an acute grade VIA facial nerve function. We suggest that it is possible to predict the facial nerve function based on intraoperative threshold testing.
AIM: Standardization of the technique to section the extratemporal facial nerve in rats and creation of a scale to evaluate facial movements in these animals before and after surgery. STUDY DESIGN: Experimental. METHOD: twenty Wistar rats were anesthetized with ketamine xylazine and submitted to sectioning of the facial nerve near its emergence through the mastoid foramen. Eye closure and blinking reflex, vibrissae movement and positioning were observed in all animals and a scale to evaluate these parameters was then created. RESULTS: The facial nerve trunk was found between the tendinous margin of the clavotrapezius muscle and the auricular cartilage. The trunk was proximally sectioned as it exits the mastoid foramen and the stumps were sutured with a 9-0-nylon thread. An evaluation and graduation scale of facial movements, independent for eye and vibrissae, was elaborated, together with a sum of the parameters, as a means to evaluate facial palsy. Absence of eye blinking and closure scored 1; the presence of orbicular muscle contraction, without blinking reflex, scored 2; 50% of eye closure through blinking reflex, scored 3, 75% of closure scored 4. The presence of complete eye closure and blinking reflex scored 5. The absence of movement and posterior position of the vibrissae scored 1; slight shivering and posterior position scored 2; greater shivering and posterior position, scored 3 and normal movement with posterior position, scored 4; symmetrical movement of he vibrissae, with anterior position, scored 5. CONCLUSION: The rat anatomy allows easy access to the extratemporal facial nerve, allowing its sectioning and standardized suture. It was also possible to establish an evaluation and graduation scale of the rat facial movements with facial palsy based on the clinical observation of these animals.
BACKGROUND: The functional and cosmetic results after hypoglossal-facial nerve anastomosis (HFA) have primarily been described using a subjective grading system of good, fair, or poor. To obtain more objective results, the postoperative mimic function was investigated using a combination of clinical and electrophysiological methods. METHODS: A total of 29 patients with hypoglossal-facial anastomosis were evaluated using a standardized questionnaire and the Stennert's paralysis index as clinical scoring system and electroneurography (NMG/ENoG) and electromyography (EMG) as electrophysiological assessments. RESULTS: Twenty-six of 29 patients (89%) judged their own facial function as very good or good, and three as poor. Under resting tone conditions, no patient showed a difference between palpebral fissures (> 3 mm), an ectropium, a substantial loss of nasolabial fold, or a drop of angulus oris (> 3 mm). With attempted movement, the lid closure was complete in 76% of patients, and the cornea was lid-covered in 100%. Sixty-seven percent of the patients were able to whistle. The second upper incisor was visible (full width) in 19%. No patient could frown sufficiently or expose the upper and lower canine teeth. The mean Stennert's score decreased from 9 to 4 after surgery. The relative amplitudes of the NMGs were increased in patients with low clinical indices. Patients with a complete eye closure showed a higher density of EMG patterns in their orbicularis oculi muscles. No significant differences for clinical or electrophysiological parameters could be observed based on age, sex, or time point of operation. CONCLUSION: Combining the Stennert's paralysis index with NMG and EMG allows a more objective assessment of functional and cosmetic results after HFA.
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Hypoglossal-facial nerve anastomosis was carried out in 20 adult guinea pigs. Electromyographic responses of orbicularis oculi muscle evoked by blink reflex were recorded 2, 4, and 6 months after surgery. Then the anastomotic site was reopened, and a segment of buccal branch and the anastomotic trunk were resected for detailed histologic study. Regenerated axons were counted and the cross-sectional area of axons and fasciculi was measured. Data obtained from both blink reflex measurement and histologic study demonstrate a good quality of regeneration of the facial nerve from the hypoglossal nerve completed 6 months after the operation. In addition a new nerve bundle was regenerated from the proximal stump of the facial nerve connecting to the anastomotic site in 80% of the animals. Postoperative change in innervation pattern of the facial nerve was also illustrated.
OBJECTIVE: To explore of the anatomic basis of the anastomosis of the facial nerve with the phrenic nerve. METHOD: Bilateral microsurgical dissection was performed on eleven human cadavers fixed with formalin. The following length data were measured with calipers: the distance between the bifurcation of the facial nerve trunk and the phrenic nerve root, the useful length of the facial nerve trunk and the phrenic nerve, and the distance between the overlapped nerve ends. RESULT: The length from the root of the the phrenic nerve to the level of the subclavian vein was (7.2 +/- 1.6) cm. The length from the root of the phrenic nerve to the bifurcation of the facial nerve trunk was (7.23 +/- 0.9) cm. The length from the bifurcation of the facial nerve trunk to the level below the horizontal semicircular canal was 2.7-3.5 cm, 1.0-1.5 cm longer than that cut below the level of the stylomastoid foramen. The cutting nerve ends were placed side by side. The distance between the overlapped nerve ends was 0.4-1.8 cm. CONCLUSION: In 20 specimens the tension-free anastomosis of the facial nerve with the phrenic nerve that cut in the subclavian vein level can be achieved, in 2 specimens the tension-free anastomosis can not be achieved.
Surgical reconstruction of the facial nerve is common clinical practice following destruction of the intracranial facial nerve. Delayed hypoglossal-facial anastomosis (HFA) is the procedure of choice, although the effect of delay on outcome remains unclear. To study the effect of delayed anastomosis on reinnervation, we sutured the proximal stump of a freshly transected hypoglossal nerve of Wistar rats to the distal stump of the ipsilateral facial nerve, which had been transected 7-56 days earlier. Animals that had received HFA without delay served as the control group. Forty days after HFA, horseradish peroxidase (HRP) was injected into the whisker pad; 2 days later, the animals were killed. Reinnervation was assessed by determining the proportion of labeled neuronal cell bodies in the brainstem. The control group had 68% reinnervation of these muscles by hypoglossal neurons and had 32% reinnervation by facial neurons. When the distal facial nerve had been allowed to degenerate for 7 days before HFA, reinnervation of the hypoglossal nerve decreased to 54%, and reinnervation by the facial nerve increased to 46%. However, after a delay of 10-56 days, the hypoglossal fraction increased and stabilized at 77%, and the facial motoneuron fraction decreased to 23%. The presence of new neuromuscular junctions was confirmed by HRP labeling of motor end plates in vivo and by electromyography. We conclude that, under the conditions of hypoglossal-facial crossed nerve suture, the predegeneration of the distal stump of a transected facial nerve enhances the reinnervation of facial muscles by hypoglossal axonal sprouts.
Delayed facial nerve palsy, a condition characterized by spontaneous deterioration of facial nerve function in patients who had otherwise normal or near-normal facial function in the immediate postoperative period, has been reported in 15 to 29% of patients undergoing microsurgical resection of vestibular schwannomas. One putative mechanism for its occurrence suggests that edematous entrapment of the facial nerve in the meatal foramen (the narrowest segment of the internal auditory canal) may lead to nerve ischemia or necrosis and subsequent facial nerve dysfunction. To assess whether meatal decompression may help reduce the incidence of delayed facial nerve palsy during microsurgical resection of acoustic tumors, we compared 25 patients undergoing translabyrinthine removal of acoustic neuromas who received prophylactic decompression of the labyrinthine segment of the facial nerve (Group 1) with 40 patients who did not receive facial nerve decompression (Group 2). No patients in Group 1 had a delayed progressive facial paralysis with degeneration. In contrast, when Group 2 patients with larger, average-sized tumors were reviewed, eight patients (20%) developed delayed degeneration. These findings suggest that decompression of the labyrinthine segment may be of value in acoustic tumor surgery in reducing delayed facial nerve dysfunction. Further study is indicated in this important area.
PURPOSE: To estimate the value of noncontrast and contrast-enhanced T1-weighted MR imaging in detecting the underlying mechanisms of injury and regeneration in immediate- or delayed-onset posttraumatic peripheral facial nerve palsy. METHODS: Twenty-four patients with posttraumatic peripheral facial nerve palsy were examined on a 1.5-T MR imaging unit with precontrast and postcontrast T1-weighted spin-echo and gradient-echo sequences. RESULTS: Abnormal enhancement of the distal intrameatal nerve segment was visible in 92% of the patients up to 2 years after their initial trauma. A hematoma within the geniculate ganglion was seen in 33% of the patients with a longitudinal fracture. The greater superficial petrosal nerve (in 32% of patients) and the geniculate ganglion (in 48% of patients) were thick and intensely enhancing. Hematoma within the cochlea/vestibule or enhancement of the cochlea/vestibule and the vestibulocochlear (eighth) nerve was observed in transverse fractures. CONCLUSION: MR images can show long-lasting abnormal nerve enhancement, especially in the distal intrameatal nerve segment, related to the long-lasting breakdown of the blood/peripheral nerve barrier associated with nerve degeneration and regeneration after traumatic stretching of the greater superficial petrosal nerve. Additionally, intraoperatively observed perineural and intraneural scar formation leads to thickening and intense enhancement of the affected nerve segments on MR images. A hematoma in the region of the geniculate ganglion can be seen in some but not all patients. Associated damage of the inner ear structures in patients with transverse fractures is also visible on MR images.
Terminal arrangements of communicating branches between the buccal nerve (V) and the facial nerve (VII) have yet to be precisely determined. To clarify distributions and relationships to facial muscles, detailed morphological examination of the two nerves was performed in the buccal region. The facial skin and underlying tissues of three cadavers were removed en bloc from the surface of the skulls and dissected from outside and inside. Arrangements of the facial muscles, nerves, and associated structures were observed. In all specimens, the communicating buccal nerve (CBN) was detected, largely covering the buccal region. The CBN gave off multidirectional twigs around the facial vein, some of which reached the anterior part of the zygomaticus major muscle. Several twigs of the CBN joined proximally with the zygomatic and buccal branches of the facial nerve. Ramified junctions that interconnected the lower zygomatic and upper buccal branches of the facial nerve were observed near sites where the CBN joined. Anterior twigs of the CBN supplied the longitudinal area lateral to the mouth, where many muscles converged. This study presents a precise morphological pattern of the CBN, suggesting functional contribution of the CBN to control of orofacial movements.
OBJECTIVES/HYPOTHESIS: Most patients with primary parotid cancer present with normal facial nerve function. The common surgical strategy for these patients is to perform a parotidectomy with facial nerve preservation. Nevertheless, the functional outcome for the facial nerve and oncological outcome is unclear. STUDY DESIGN: Medical records of 211 patients treated from 1986 to 2000 in an university hospital were reviewed. One hundred seven patients with primary surgery for primary parotid cancer and long-term follow-up were analyzed retrospectively. METHODS: The characteristics, treatment, and oncological outcome were evaluated using hospital chart data. All patients with postoperative facial paresis were had follow-up with electromyography until recovery or permanent paresis became apparent. RESULTS: Ninety-one patients had a normal preoperative function. Facial nerve preservation during surgery by total parotidectomy was possible in 79 patients, whereas in 28 patients a radical parotidectomy was necessary. Otherwise, the oncological characteristics of both groups were not different. Directly after total parotidectomy, half of the patients presented a facial paresis but only two patients (2%) developed a permanent partial paresis. The 5-year disease-free rate and the 5- and 10-year survival rates were 65%, 83%, and 54%, respectively. After radical parotidectomy, the results were not significantly different. The 5-year disease-free rate and the overall 5- and the 10-year survival rates were 56%, 62%, and 42%, respectively. CONCLUSION: Treatment of primary parotid cancer with preoperatively normal facial nerve function by standardized parotidectomy and precise microsurgical preservation of the facial nerve is often possible. This approach demonstrates favorable oncological results with a low level of long-term facial nerve morbidity.
A 38-year-old man was referred by his general practitioner to our department on 28 October 1991, with a 2-week history of vertigo. A left aural polyp was identified. The audiogram showed a moderate conductive loss on the left side. Computed tomography (CT) and magnetic resonance imaging (MRI) confirmed the presence of the expanding lesion in the descending portion of the facial nerve. However, there was no seventh nerve paresis. At operation, the neurinoma (Schwannoma) filled the middle ear cleft and extended from the genu to the stylomastoid foramen. The floor of the middle ear had been eroded, exposing the jugular bulb. Facial nerve paresis is the usual presenting feature of a facial neurinoma. The case is presented for the reason that the absence of facial palsy as a presenting feature is rather rare, especially in the cases with large tumor and extensive bone erosion.
OBJECTIVE: To evaluate whether the intraoperative stimulus threshold and response amplitude measurements from facial electromyography can predict facial nerve function at 1 year after vestibular schwannoma resection. STUDY DESIGN: Prospective study. SETTING: Tertiary academic center. PATIENTS: Seventy-four consecutive vestibular schwannoma patients. INTERVENTION: The minimal stimulus intensity (in milliamperes) and electromyographic response amplitude (in microvolts) were recorded during stimulation applied to the proximal facial nerve after vestibular schwannoma removal. MAIN OUTCOME MEASURE: Facial nerve outcomes at 1 year were evaluated using the House-Brackmann scale. Analysis was then performed to evaluate whether these electrophysiologic recordings and tumor size could predict facial nerve functional outcomes. RESULTS: Of the 74 patients, 66 of 74 (89%) had House-Brackmann Grade I or II facial nerve function and 8 of 74 (11%) had House-Brackmann Grade III-VI function at 1 year after surgery. If standards were set for intraoperative minimal stimulus intensity of 0.05 mA or less and response amplitude of 240 microV or greater, the authors were able to predict a House-Brackmann Grade I or II outcome in 56 of 66 (85%) patients at 1 year after surgery. With these same electrophysiologic parameters, only 1 of 8 (12%) House-Brackmann Grade III-VI patients also met this standard and thus gave a false-positive result. Logistic regression analysis of the data showed that both a stimulus threshold of 0.05 mA or less and a response amplitude of 240 microV or greater predicted a House-Brackmann Grade I or II outcome with a 98% probability. However, stimulus threshold or response amplitude alone had a much lower probability of the same result. In addition, although tumor size was found to independently predict facial nerve outcomes at 1 year, it did not improve the ability to predict facial nerve function over a model using stimulus intensity and amplitude alone. CONCLUSION: Individually, minimal stimulus intensity or response amplitude was less successful in predicting long-term postoperative facial nerve function. However, if both parameters are considered together, the study demonstrates that they are good prognostic indicators for facial nerve function at 1 year after surgery.
OBJECT: The goal of this study was to assess the clinical results of hypoglossal-facial nerve attachment (HFA), which was primarily performed in patients following excision of tumors of the cerebellopontine angle. In six of the patients a new side-to-end procedure was used. METHODS: The authors have performed a retrospective study of 33 patients who underwent HFA, including 24 classic end-to-end, three May, and six side-to-end procedures. For the latter procedure, a hemihypoglossal-facial nerve attachment was performed by rerouting the intratemporal facial nerve; this avoided the jump-cable graft used in May's technique. The goal of the new procedure is to reduce the incidence of morbidity due to hemilingual paralysis (difficulty in chewing, speaking, and swallowing). The incidence of hemilingual paralysis was evaluated based on the findings of a questionnaire that was completed by the patients. The patient's facial mobility was assessed using the House and Brackmann grading system and the author's analytic scoring system. CONCLUSIONS: The HFA offers good functional results. Of the 28 cases evaluated, nine had House and Brackmann Grade III, 17 Grade IV, and only two Grade V at 18 months. When the new technique of side-to-end hemihypoglossal-facial nerve attachment was used, there was considerable reduction, if not complete disappearance, of lingual morbidity and the facial functional results were constant and satisfactory: there were five patients with House and Brackmann Grade III and one with Grade IV, and their mean percentage of facial mobility was 43.3%.
OBJECTIVE: Analyze the incidence and factors responsible for postparotidectomy facial nerve paralysis when the surgery is performed with the routine use of facial nerve monitoring. STUDY DESIGN: A prospective, nonrandomized study. METHODS: Seventy consecutive patients underwent parotidectomy with intraoperative facial nerve monitoring. Two devices were used: a custom mechanical transducer and a commercial electromyograph-based apparatus. All patients were analyzed, including those with cancer and those with deliberate or accidental sectioning of facial nerve branches. The outcome variables were the motor facial nerve function according to the House-Brackmann grading scale (HB) at 1 week (temporary paralysis) and 6 to 12 months (definitive paralysis). Facial nerve grading was performed blindly from reviewing videotapes. RESULTS: The overall incidence of facial paralysis (HB>1) was 27% for temporary and 4% for permanent deficits. Most of the deficits were partial, most often concerning the marginal mandibular branch. Temporary deficits with HB scores of greater than 2 were only present in patients with parotid cancer or infection. Permanent deficits were present in three patients, including one patient with facial nerve sacrifice. Factors significantly associated with an increased incidence of temporary facial paralysis include the extent of parotidectomy, the intraoperative sectioning of facial nerve branches, the histopathology and the size of the lesion, and the duration of the operation. CONCLUSIONS: Despite a stringent accounting of postoperative facial nerve deficits, these data compare favorably to the literature with or without the use of monitoring. An overall incidence of 27% for temporary facial paralysis and 4% for permanent facial paralysis was found. Although the lack of a control group precludes definitive conclusions on the role of electromyograph-based facial nerve monitoring in routine parotidectomy, the authors found its use very helpful.
Facial nerve specimens removed from ten patients who underwent hypoglossal-facial nerve anastomosis for facial palsy following removal of cerebellopontine angle tumors were studied histologically. Facial nerve function prior to the anastomosis surgery and the degree of postoperative functional recovery were compared with the histological results. The recovery of facial palsy after the anastomosis surgery was excellent or satisfactory in nine patients and the endoneurium within the nerve fascicles was well-preserved. The recovery of facial palsy was poor in one patient who had severe fibrosis of the endoneurium. The histological and ultrastructural features of the facial nerve were closely related to the occurrence of facial palsy prior to tumor removal, the status of the nerve after tumor removal, and the interval between tumor removal and anastomosis surgery. Based on these histological and functional relationships, the timing and indications for anastomosis surgery are discussed.