Prediction of Facial Nerve Function After Surgery for Cerebellopontine Angle Tumors: Use of a Facial Nerve Stimulator and Monitor

A series of 18 patients undergoing surgery for cerebellopontine angle tumors is reported. Patients were grouped according to size of tumor (0 to 2.5 cm, 11 cases; more than 2.5 cm, 7 cases). In all, the facial nerve was identified and conductance assessed by monitoring the facial electromyographic response to facial nerve stimulation. Postoperative facial nerve function was graded clinically after 3 months according to the House scale. Tumor removal was complete in all cases. In patients with tumors up to 2.5 cm the facial nerve was intact to visual inspection at the end of the procedure in all but one, where partial division was evident. In this group intraoperative facial nerve stimulation indicated electrical integrity in 8 of the 11 cases, all of which regained good facial nerve function postoperatively (House grades I and II). Nerve conduction was lost during the operation in the remaining three patients with small tumors; two subsequently developed a moderately severe (grade IV) dysfunction and the third, a total paralysis (grade VI). In the large (more than 2.5 cm) tumor group the facial nerve was anatomically intact in five of the seven cases, partially divided in one, and completely sectioned in the remaining case. Facial nerve stimulation indicated functional integrity in three patients, two of whom developed moderate (grade III) and the third a severe (grade V) dysfunction. In the other four cases nerve function could not be detected at operation; three of these developed a moderate facial nerve dysfunction (grade III/IV) and the final case a complete paralysis (grade VI). Intraoperative facial nerve monitoring appeared to predict eventual facial function accurately in the small tumor group, but did not predict facial nerve recovery reliably following surgery for larger tumors.     

Management of iatrogenic facial nerve palsy and labyrinthine fistula in mastoid surgery

A 6-year review of complications of mastoid surgery between June 1995 and June 2001 revealed five cases with serious iatrogenic complications from mastoid surgery, of which four were facial nerve palsy and two were labyrinthine fistula. One of these patients had concomitant facial nerve palsy and labyrinthine fistula. There were two cases of complete facial nerve palsy (House Brackmann grade VI) and two cases of incomplete palsy (House Brackmann grades IV and V). The second genu was the site of injury in three of the four cases. Of the four cases with facial nerve palsy, two patients had full recovery (House Brackmann grade I), one recovered only to House Brackmann grade III, and one was lost to follow-up. Both patients with labyrinthine fistula had postoperative vertigo and profound sensorineural hearing loss. The site of iatrogenic fenestration was the lateral semicircular canal in both cases.     

Improved preservation of facial nerve function in the infratemporal approach to the skull base

Although the infratemporal approach described by Fisch provides excellent exposure of the jugular foramen, intrapetrous carotid artery, and lateral skull base, the anterior displacement of the seventh cranial nerve often results in temporary facial paralysis. The use of a modified technique for facial nerve mobilization resulted in significant improvement of both early and final facial function. Since that earlier report, continuous intraoperative electrical facial nerve monitoring has been used during the infratemporal approach in 20 additional cases. Immediate postoperative facial function was normal in 93% of the monitored cases and in 70% of the cases in the unmonitored group. More importantly, no patients in the monitored group developed grade V or VI weakness after surgery, whereas 48% of the unmonitored patients had grade V or VI weakness during the early postoperative period. This article will describe how intraoperative facial nerve monitoring is used during infratemporal surgery and will compare early facial function in 31 unmonitored patients with early facial function in 20 monitored procedures.     

听神经瘤显微手术面神经损伤的预防

目的总结与分析听神经瘤显微手术中预防面神经损伤的方法。方法经MRI和（或）CT检查确诊的大型听神经瘤（≥4．0cm）180例（72％）及中型听神经瘤（2．4～4．0cm）70例（28％）。均采用经患侧枕下乙状窦后入路保留面神经的显微手术。注意三大解剖关系：骨性解剖、蛛网膜解剖、神经与血管的解剖。肿瘤囊内减压后,确认面神经的起始位置、面神经与肿瘤的关系、面神经变形与扭曲、面神经分离的方法、面神经的断裂端-端吻合。随访6个月～1年。结果肿瘤全切除240例（96．0％）;次全切除10例（4．0％）,其中死亡1例（0．4％）。面神经功能评定：Ⅰ级214例（85．6％）;Ⅱ级25例（10．0％）;Ⅲ级5例（2．1％）;Ⅳ级5例（2．1％）。结论术中注意典型的解剖位置,正确的手术入路和显微手术技术可达到较高的肿瘤全切除率,提高面神经的功能保全率。     

Facial nerve reconstruction using a split hypoglossal nerve with preservation of tongue function

A prospective study conducted on 13 patients suffering from complete facial nerve injury (for 4 months up to 2 years) aimed to show that using the split hypoglossal nerve allows for reconstruction of the facial nerve with preservation of tongue function. The hypoglossal nerve was split longitudinally. For each half, a split of the hypoglossal nerve's response was measured intraoperatively by recording the compound muscle action potential of the tongue muscle. The half that showed the least response was selected for anastomosis. The facial nerve was transected at the stylomastoid foramen, and its distal part underwent a direct anastomosis with the selected half of the hypoglossal nerve. The six grades of the House-Brackman grading system were used to analyze the results. The average postoperative follow-up period was 3 years. Before surgery, 12 patients in this study were graded VI, with total paralysis, and 1 was graded V. After surgery, 2 of the 13 patients showed mild dysfunction (grade II), 7 patients showed moderate dysfunction (grade III), 3 patients showed moderately severe dysfunction (grade IV), and 1 patient showed a severe dysfunction (grade V). Microsurgical facial nerve reconstruction using a split hypoglossal nerve results in functional facial nerve improvement with preservation of tongue function.     

New technique of side-to-end hypoglossal-facial nerve attachment with translocation of the infratemporal facial nerve.

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%.     

Reliability of the "Sydney," "Sunnybrook," and "House Brackmann" facial grading systems to assess voluntary movement and synkinesis after facial nerve paralysis.

OBJECTIVE: To investigate the extent of within-system reliability and between-system correlation for the "Sydney" and "Sunnybrook" systems of grading facial nerve paralysis, and to examine the interobserver reliability and agreement of the "House Brackmann" grading system. STUDY DESIGN: A fixed-effects reliability study in which 6 otolaryngologists viewed videotapes of patients with facial nerve paralysis. SETTING: University and medical Centers. PATIENTS: Patients with unilateral lower motor neurone facial nerve dysfunction greater than 1 year after onset, none of whom had undergone surgical reanimation procedures. Intervention Twenty-one patients with facial nerve paralysis were videotaped while they performed a protocol of facial movements. Six otolaryngologists viewed the videotapes and scored them with the Sydney and Sunnybrook systems, and then gave a House Brackmann grade. MAIN OUTCOME MEASURE: The 3 systems of grading facial nerve paralysis were evaluated and compared with the use of intraclass correlation coefficients, Pearson's weighted kappa, and percentage exact agreement values. RESULTS: The Sydney and the Sunnybrook systems had good intrasystem reliability and high intersystem association for the assessment of voluntary movement. Grading of synkinesis was found to have low reliability both within and between systems. The House Brackmann system had substantial reliability as shown by weighted kappa but had a percentage exact agreement of 44%. CONCLUSIONS: For clinical grading of voluntary movement, there is good correlation between ratings given on the Sydney and Sunnybrook systems, and within each system there is good reliability. The assessment of synkinesis was far less reliable within, and less related between, systems. Although the reliability of the House Brackmann system was found to be high, examination of individual grades revealed some wide variation between trained observers.     

Side-to-end hypoglossal-facial anastomosis via transposition of the intratemporal facial nerve

Summary The technique of facial nerve repair with side-to-end hypoglossal-facial anastomosis is presented and evaluated in five patients who were operated on for facial nerve paralysis after acoustic schwannoma surgery, or had cranial base trauma. The end-to-end hypoglossal-facial anastomosis is accompanied by hemilingual paralysis, with difficulty in swallowing, chewing and speaking. In this new technique, the facial nerve is mobilised in the temporal bone, transected at the second genu and transposed to the hypoglossal nerve where a tensionless side-to-end anastomosis is performed. The hypoglossal nerve is transected in oblique fashion to about one third of its circumference. We were able to achieve a tensionless anastomosis in all patients. The idea is to bring about re-innervation of the previously denervated tissue via a collateral sprouting of axons of the donor nerve through the site of coaptation without sacrificing the innervation of the donor nerve’s original targets. With side-to-end hypoglossal-facial anastomosis, two patients attained a House- Brackmann grade of III (one of them with independent movement of eyelids and mouth); one achieved grade IV, another grade V and grade VI. No patient had hemilingual atrophy nor any problems associated with swallowing or chewing.     

Electroneurography: preoperative facial nerve assessment for tumors of the temporal bone

Tumors of the temporal bone and cerebellopontine angle may be associated with subclinical facial nerve degeneration, despite clinically normal facial function. To determine if preoperative neurophysiologic testing might predict postoperative facial function after tumor surgery, preoperative facial electroneurography (ENoG) was performed in 82 patients with confirmed tumors of the temporal bone and cerebellopontine angle. In patients with acoustic neuroma, preoperative ENoG amplitude reduction varied directly with tumor size. In addition, a statistically significant association between impaired postoperative facial function and acoustic neuroma size greater than 2.5 cm was found. However, preoperative ENoG amplitude reduction did not accurately predict postoperative facial function. These findings suggest that factors, such as the type and size of tumor, the microanatomic relationship between the facial nerve and the neoplasm, and/or desynchronization of the evoked motor-unit volley, may effect results obtained with ENoG in this setting.     

Facial nerve preservation and tumor control after gamma knife radiosurgery of unilateral acoustic tumors

To assess the long-term risk of facial nerve dysfunction after unilateral acoustic tumor stereotactic radiosurgery, we retrospectively analyzed our initial experience in 98 unilateral acoustic tumor patients who were evaluated at least 2 years after treatment. This observation interval permits an analysis of both the risk of onset and the potential for recovery of facial nerve function. The overall risk of developing any degree of delayed transient or permanent postoperative facial neuropathy was 21.4% (21 of 98 patients). Only one patient undergoing radiosurgery alone had poor residual facial nerve dysfunction worse than House-Brackmann grade III. Normal facial nerve function (House-Brackmann grade 1) was preserved in 95% of patients with small tumors (10 mm or less petrous-pons dimension) and in 90% of patients who had useful hearing and normal facial function preoperatively. Normal facial function was preserved in all patients with intracanalicular acoustic tumors. The risk of delayed facial neuropathy was reduced by performing radiosurgery when tumors were small (1000 mm(3) or less), by enclosing the tumor within the 50% isodose volume, by using multiple small radiation isocenters, and by detailed identification of the tumor volume using stereotactic magnetic resonance imaging.     

Facial nerve stimulation and postparotidectomy facial paresis.

OBJECTIVE: We sought to evaluate the association of intraoperative facial nerve stimulation and postoperative facial nerve paresis/paralysis. STUDY DESIGN AND SETTING: Eighty-nine consecutive patients who underwent parotidectomy by a single surgeon were retrospectively analyzed for age, gender, size of tumor, tumor histology, and intraoperative use of a facial nerve stimulator. RESULTS: Facial paresis developed in 22% (10 of 46) of the patients who were stimulated and 22% (5 of 23) of the nonstimulated patients. These results were not statistically significant (P = 1.0000). There was no permanent paralysis in either group. The tumor type and size and gender and age of the patient did not affect the outcome. CONCLUSION: There was no difference in the incidence of postoperative facial nerve paresis or paralysis between the stimulated and nonstimulated patients. Routine use of a stimulator is not necessary during parotid surgery because its use does not prevent or promote facial nerve injury.     

Cerebellopontine angle epidermoids: results of surgical treatment

Epidermoids, or congenital cholesteatomas, constitute about 0.2% to 1.5% of intracranial tumors, and 3% to 5% of tumors of the cerebellopontine angle (CPA). We review the surgical management of CPA epidermoids in 13 patients at the House Ear Clinic for the years 1978 to 1993. There were seven male and six female patients, ranging in age from 27 to 59 years (average, 40 years). Tumors ranged in size from 3.5 cm to 7.0 cm, and the surgical approach was tailored to the tumor extent and location. All patients complained at presentation of unilateral hearing loss, and nine had poor speech discrimination (less than 50%) preoperatively. Serviceable hearing was preserved in two patients. Two patients presented with facial nerve symptoms, and four cases had postoperative permanent facial nerve paralysis (House-Brackmann Grade V or VI). There were no surgical deaths. Four patients required second surgeries to remove residual cholesteatoma. Compared with prior series, we describe a higher rate of total tumor removed, as well as a higher rate of second operations, indicating a more aggressive approach to these lesions.     

Cerebellopontine Angle Epidermoids: Results of Surgical Treatment

Epidermoids, or congenital cholesteatomas, constitute about 0.2% to 1.5% of intracranial tumors, and 3% to 5% of tumors of the cerebellopontine angle (CPA). We review the surgical management of CPA epidermoids in 13 patients at the House Ear Clinic for the years 1978 to 1993. There were seven male and six female patients, ranging in age from 27 to 59 years (average, 40 years). Tumors ranged in size from 3.5 cm to 7.0 cm, and the surgical approach was tailored to the tumor extent and location. All patients complained at presentation of unilateral hearing loss, and nine had poor speech discrimination (less than 50%) preoperatively. Serviceable hearing was preserved in two patients. Two patients presented with facial nerve symptoms, and four cases had postoperative permanent facial nerve paralysis (House-Brackmann Grade V or VI). There were no surgical deaths. Four patients required second surgeries to remove residual cholesteatoma. Compared with prior series, we describe a higher rate of total tumor removed, as well as a higher rate of second operations, indicating a more aggressive approach to these lesions.     

Intracanalicular and intratemporal facial nerve schwannomas

Facial nerve schwannomas can mimic acoustic neuromas. We report herein two cases: a purely intracanalicular and an intratemporal facial nerve tumor extending into the internal auditory canal and the cerebellopontine angle. These tumors have to be suspected in patient with small-size tumors presenting with facial paralysis. We advocate translabyrinthine or middle fossa approach to facilitate nerve anastomosis. The establishment of the correct properative diagnosis is difficult, but the patient must be warned about the impossibility of preserving the facial nerve in these tumors.     

Intratemporal facial nerve hemangiomas

Facial nerve hemangiomas are benign vascular tumors that arise within the temporal bone and have a histologic appearance similar to both cavernous hemangiomas and vascular malformations. In contrast to facial nerve schwannomas, these are extraneural tumors that cause symptoms by compression and tend to produce deficits when very small in size. We report our experience at the House Ear Clinic with 34 patients having these nonglomus intratemporal vascular tumors. Hemangiomas arising in the internal auditory canal tend to produce a progressive sensorineural hearing loss and are demonstrated with magnetic resonance imaging (MRI), whereas those at the geniculate ganglion are usually first seen with facial nerve symptoms and may require high-resolution computerized tomography (CT) for detection. Facial electromyography is helpful in establishing the diagnosis. Because of their extraneural nature, early diagnosis can permit removal of the tumor with preservation of facial nerves in some patients.     

Predictive value of postoperative electrophysiologic testing of the facial nerve after cerebellopontine angle surgery

Our objective was to assess the ability of postoperative electroneuronography (ENoG) and electromyography (EMG) to predict clinical facial function 1 year postoperatively in patients with facial paralysis and an intact facial nerve after cerebellopontine angle surgery. The study was a prospective, nonrandomized, uncontrolled clinical trial on an outpatient basis, at a tertiary care hospital. Primary eligibility criteria include: (1) cerebellopontine angle (CPA) surgery with anatomical preservation of facial nerve, (2) complete facial nerve paralysis; and (3) 1 year follow-up. ENoG and EMG were measured at 1 and 3 months postoperatively, House-Brackmann facial nerve grade at 1 year postoperatively. The Kendall coefficient of rank correlation demonstrated that the 1 and 3 month postoperative ENoG data were significant predictors of ultimate facial nerve outcome. Tracking multiple ENoG examinations in a single patient, over time was of little predictive value. EMG was a poor predictor of facial nerve outcome. In general, patients with delayed facial nerve paralysis had better ultimate facial function than patients with immediate paralysis. Postoperative ENoG, but not EMG was a statistically significant predictor of ultimate facial nerve outcome after CPA surgery. Patients with delayed facial paralysis had better outcomes than those with immediate facial paralysis.     

The facial nerve in medial acoustic neuromas

OBJECT: Functional results after surgery for acoustic neuromas that have little or no growth within the internal auditory canal are controversial, because these medial tumors can grow to a considerable size within the cerebellopontine angle (CPA) before symptoms occur. METHODS: A prospective study was designed to evaluate the surgical implications of the course of the facial nerve within the CPA on medial acoustic neuromas. This study included a consecutive series of 22 patients with medial acoustic neuromas (mean size 32 mm, range 17-52 mm) who underwent surgery via a suboccipitolateral approach between 1997 and 2001. All patients underwent pre- and postoperative magnetic resonance imaging and preoperative electromyography (EMG). Evaluation was based on continuous intraoperative EMG monitoring and video recordings of the procedure. All patients were reevaluated at a mean of 19 months (6-50 months) postsurgery. Preoperative evaluation of facial nerve function revealed House-Brackmann Grade I in six, Grade II in 14, and Grade III in two patients. During surgery a distinct splitting of the nerve at the root exit zone through its intracisternal course was seen in eight patients and documented by selective electrical stimulation. The facial nerve was separated into a smaller portion that ran cranially and parallel to the trigeminal nerve, and a larger portion on the anterior tumor surface. Both components joined anterior to the porus without major spreading of the nerve bundle. In two cases the nerve was found on the posterior surface of the cranial tumor. In one case the facial nerve entered the porus of the canal at its lower part, obtaining the expected anatomical position proximally within the middle portion of the canal. An anterior cranial, middle (five cases each), or caudal course (two cases) was seen in the remaining patients. After surgery, facial nerve function deteriorated in most cases; on follow-up evaluation House-Brackmann Grade I was found in 11, Grades II and III in 10, and Grade V in one patient. CONCLUSIONS: The facial nerve requires special attention in surgery for medial acoustic neuromas, because an atypical course of the nerve can be expected in the majority of cases. A split course of the nerve was found in 36% of the cases presented. Meticulous use of intraoperative facial nerve stimulation and continuous monitoring ensures facial nerve integrity and offers good functional results in patients with medial acoustic neuromas.     

Primary facial nerve tumors within the skull

In a series of 527 cerebellopontine angle tumors, there were 416 cases of acoustic nerve tumors and 14 cases of primary tumor of the facial nerve in the petrous bone or intracranial cavity. Six additional patients were presumed to have facial tumors, although they were not operated on. Of the 14 verified facial nerve tumors, all but two were neurinomas and 11 had important intracranial extensions into the middle and/or the posterior fossa. In most of these 14 cases, surgical removal was performed via the translabyrinthine route, which is advantageous in that it displays the characteristic relationship of the tumor to the facial nerve, and facilitates nerve repair. The clinical and radiological features of these facial nerve lesions are discussed and also the indications for surgical treatment which, as the unoperated cases illustrate, is not always necessary.     

MRI of the facial nerve during paralysis

Gadolinium-enhanced MRI was used to evaluate 10 patients with Bell's palsy and one patient with facial paralysis secondary to Lyme disease. Nine of the eleven patients showed increased signal intensity of their facial nerve with gadolinium-enhanced MRI. In all nine patients, the facial nerve was involved at the labyrinthine, geniculate ganglion and proximal tympanic portions of the facial nerve, while two of the nine patients also had involvement of the mastoid segment of the facial nerve. Patients whose facial nerve enhancement was limited to the labyrinthine, geniculate ganglion and proximal tympanic facial nerve ultimately had complete return of facial function. Patients whose facial nerve enhanced in the mastoid segment experienced incomplete return of facial function. Gadolinium is effective in localizing the site of inflammation during facial paralysis. Those patients with enhancement localized to the labyrinthine, geniculate ganglion and proximal tympanic segments were more likely to regain complete facial function. In contrast, patients who had enhancement of the mastoid segment of the facial nerve had poorer prognoses for complete return of facial function.