Long-term Facial Function Research Articles

Facial nerve function after translabyrinthine vestibular schwannoma surgery

To evaluate the long-term facial function of patients after translabyrinthine vestibular schwannoma [VS] surgery and identify factors that influence these outcomes. A retrospective review was performed that included 580 consecutive patients who underwent translabyrinthine craniotomy for removal of VS at a tertiary referral neurotologic practice between February 2000 and July 2004. A total of 512 patients who underwent primary microsurgical treatment of sporadic unilateral VS met inclusion criteria. Patient and tumor characteristics as well as perioperative complications are described. Perioperative and long-term facial function were evaluated in 392 patients who had at least 1-year follow-up. Complication rates after translabyrinthine craniotomy for VS are low. Patients with smaller tumors have significantly better postoperative facial function than those with larger tumors. Excellent long-term facial function can be expected in the majority of patients who undergo microsurgical removal of VS via the translabyrinthine approach. Alternative treatment strategies may need to be developed for the treatment of VS > 3.5 cm in order to maximize postoperative facial function.

Staged resection of large acoustic neuromas

Surgical removal of large (>3 cm) acoustic neuromas is associated with poor long-term facial nerve function results and higher complication rates. This study analyzes whether long term facial nerve function and the incidence of neurological and vascular complications is improved by resection of large acoustic neuromas in 2 or 3 stages. Among 660 patients who underwent surgical resection of acoustic neuromas between 1989 and 2002 by the senior author (J.M.K.), 34 (5%) patients underwent a staged resection of their large-sized tumors: stage I via a retrosigmoid craniotomy and stage II via a translabyrinthine approach. A retrospective chart review was performed. Tumor size, completeness of tumor removal, tumor recurrence, facial nerve function, and any complications were noted. The average tumor size was 4.4 cm with a mean postoperative length of follow-up of 6 years after the last surgery. Thirty-one patients underwent a 2-staged resection and 3 patients underwent a 3-staged resection. After their last surgery, 32 (94%) patients had excellent long-term facial function grades of House-Brackmann (H-B) I, one was H-B III, and one was H-B VI. All patients had a total or near-total (>98%) resection. There were no tumor recurrences on follow-up MRI scans. From these 71 operations, no patients required reoperation for a CSF leak. There were no deaths, strokes, hydrocephalus, or meningitis. In conjunction with the reported technical refinements, staged resection of large tumors significantly reduces morbidity and improves long-term facial nerve function. C.

Predictive factors of long-term facial nerve function after vestibular schwannoma surgery.

To assess predictive factors of long-term facial nerve function in a series of patients undergoing vestibular schwannoma surgery and to evaluate the reproducibility of the relevant parameters. Prospective. Three tertiary referral neurotology units in two separate countries. A total of 67 patients, with normal preoperative facial function and an anatomically intact facial nerve postoperatively, undergoing vestibular schwannoma surgery during a sequential 18-month period. Recording of intraoperative stimulus amplitudes (minimum intensity medial to the tumor after excision) and postoperative facial nerve function up to 2 years after surgery. Long-term facial nerve function related to tumor size, early postoperative facial nerve function, and intraoperative electrophysiologic intensities. Multivariate logistic regression model identified tumor size and the minimum intensity required to provoke a stimulus threshold event medial to the tumor after excision as independent predictors of a favorable initial outcome. Immediate facial nerve function was the only independent predictor of long-term normal function. The sensitivity of this predictor was 95% (95% confidence interval [CI], 89-100%); specificity, 83% (95% CI, 62-100%); positive predictive accuracy, 96% (95% CI, 91-100%); and negative predictive accuracy, 77% (95% CI, 54-100%). The combination of electrophysiologic intensities and tumor size are reproducible and better predictors of initial facial nerve function than any individual parameter, but long-term facial nerve function is more likely to have a better outcome if the nerve is left intact and a per-operative graft repair is not performed. The study suggests that although the best available predictor of overall long-term facial nerve outcome is the level of early postoperative function, this factor is not useful in surgical rehabilitation decision making.

Can continuous intraoperative facial electromyography predict facial nerve function following cerebellopontine angle surgery?

Intraoperative cranial nerve monitoring has significantly improved the preservation of facial nerve function following surgery in the cerebellopontine angle (CPA). Facial electromyography (EMG) was performed in 60 patients during CPA surgery. Pairs of needle electrodes were placed subdermally in the orbicularis oris and orbicularis oculi muscles. The duration of facial EMG activity was noted. Facial EMG potentials occurring in response to mechanical or metabolic irritation of the corresponding nerve were made audible by a loudspeaker. Immediate (4-7 days after tumor excision) and late (6 months after surgery) facial nerve function was assessed on a modified House-Brackmann scale. Late facial nerve function was good (House-Brackmann 1-2) in 29 of 60 patients, fair (House-Brackmann 3-4) in 14, and poor (House-Brackmann 5-6) in 17. Postmanipulation facial EMG activity exceeding 5 minutes in 15 patients was associated with poor late function in five, fair function in six, and good function in four cases. Postmanipulation facial EMG activity of 2-5 minutes in 30 patients was associated with good late facial nerve function in 20, fair in eight, and poor in two. The loss of facial EMG activity observed in 10 patients was always followed by poor function. Facial nerve function was preserved postoperatively in all five patients in whom facial EMG activity lasted less than 2 minutes. Facial EMG is a sensitive method for identifying the facial nerve during surgery in the CPA. EMG bursts are a very reliable indicator of intraoperative facial nerve manipulation, but the duration of these bursts do not necessarily correlate with short- or long-term facial nerve function despite the fact that burst duration reflects the severity of mechanical aggression to the facial nerve.

Prediction of postoperative facial nerve function in acoustic neuroma surgery

There is a need for an uncomplicated, consistent method to predict facial nerve function after acoustic neuroma surgery. A prospective study with a 2-year follow-up of 35 patients undergoing acoustic neuroma surgery was performed assessing how well intraoperative facial nerve monitor electrophysiological thresholds and facial function postsurgery can predict ultimate nerve function. Tumour size was a strong predictor of immediate (P-value < 0.0005) and long-term facial nerve function (P-value = 0.004). Immediate facial nerve function was strongly predicted by stimulus intensity (P-value = 0.007) and there was a suggestion of a relationship between long-term facial nerve response and stimulus intensity. It was not possible to predict delayed facial dysfunction nor the extent or timing of recovery of abnormal function. It is concluded that the combination of facial function at 1 month postsurgery with tumour size and stimulus thresholds is the best available indicator of ultimate facial function.

Intraoperative electromyography for predicting facial function in vestibular schwannoma surgery.

To assess the validity of intraoperative minimal stimulation threshold (MST) for predicting long-term facial function after vestibular schwannoma surgery. Prospective blinded study. MST after tumor dissection and postoperative clinical facial function, assessed using the House Brackmann grading system (HB), were used to predict long-term clinical facial function, recorded at least 6 months after surgery. Two hundred and nine consecutive patients fulfilled selection criteria and 184 had successful intraoperative electrophysiologic monitoring and were eligible for further study. MST of 0.05 mA had moderate accuracy for predicting good long-term facial function, with 94% sensitivity, 91% positive predictive value (PPV), 60% specificity, and 70% negative predictive value (NPV). A more relevant group of 77 patients with poor postoperative facial function (HB III-VI) were assessed for predicting good long-term function. Applying this criteria, test accuracy fell, with 83% sensitivity, 64% PPV, 60% specificity, and 75% NPV. Postoperative clinical facial function had a greater accuracy for predicting good long-term function, with 83% sensitivity, 79% PPV, 75% specificity, and 79% NPV. A model of predicted probabilities of good outcome (HB I and II) was derived from a logistic regression with two additive predictors (postoperative HB and MST). This demonstrated that for patients with postoperative HB grade V, MST aided prediction. Intraoperative stimulation thresholds, when assessed against a relevant group of patients with poor postoperative facial function, had poor predictive accuracy. The severity of immediate postoperative clinical facial function was the most accurate predictor of long-term outcome. MST aided long-term prediction in a small but relevant group of patients with postoperative HB grade V facial function.

Pre-operative and per-operative factors conditioning long-term facial nerve function in vestibular schwannoma surgery through translabyrinthine approach.

Facial nerve function was evaluated in 103 patients, after vestibular schwannoma removal through the translabyrinthine approach. The mean follow-up was 43 months (minimum six months). Grade I facial function was achieved in 100 per cent of stage I schwannomata compared with 36 per cent of stage IV schwannomata. Grade I or II facial function was found in 78 per cent of homogeneous schwannomata, compared with 48 per cent of heterogeneous schwannomata. Facial function was preserved in 89 per cent of cases, if the angle between the internal auditory canal and the schwannoma was > 66 degrees, compared with 54 per cent if the angle was < 66 degrees. There was 82 per cent of normal facial function when the nerve appeared normal after tumour removal, compared with 18 per cent when the nerve was traumatized. When the ratio (stimulation threshold at the internal auditory canal/stimulation threshold at brainstem) was < 2, post-operative facial function was preserved in 87 per cent of cases, compared with 13 per cent when the ratio was > 2.

Individualizing hearing preservation in acoustic neuroma surgery.

Surgical series of hearing preservation in acoustic neuroma usually emphasize a team's results with one particular technique. This report reviews acoustic neuroma outcomes of individualizing the surgical approach to patient and tumor characteristics. This study reviews 60 consecutive hearing preservation acoustic neuroma surgeries in a total series of 330 acoustic neuromas. Tumor sizes ranged from 0.3 to 4 cm in patients ranging from 23 to 74 years of age. Middle fossa surgery was performed in 57%, retrosigmoid in 43%. Overall, measurable hearing was preserved in 77%, and useful hearing in 67%. Among middle fossa cases, 85% had measurable and 74% had useful hearing. Among retrosigmoid surgeries, 65% had measurable hearing and 58% had useful hearing. Overall, long-term facial nerve function was excellent (grade I or II) in 90% and poor (grade V or VI) in 2%. There was one case of bacterial meningitis (2%), and cerebrospinal fluid leaks requiring surgery occurred in four patients (7%). The hearing preservation and other outcome parameters in this series compare favorably with other reports. We believe that individualizing the surgical approach to the patient's tumor characteristics and clinical features contributed to the high rate of hearing preservation.

Facial Nerve Outcome after Acoustic Neuroma Surgery: A Study from the Era of Cranial Nerve Monitoring

The introduction of intraoperative cranial nerve monitoring in posterior fossa surgery has greatly aided the surgeon in identification and anatomic preservation of cranial nerves. As a result, the long-term function of the facial nerve continues to improve after removal of acoustic neuroma. Herein, we report our long-term (1 year or greater) facial nerve outcome in 129 patients who underwent surgical removal of their acoustic neuromas with the aid of intraoperative neurophysiologic monitoring between 1986 and 1990. The facial nerve was anatomically preserved in 99.2% of the patients, and 90% of all the patients had grade 1 or 2 facial nerve function 1 year after surgery. Long-term facial function was inversely correlated with the size of tumor (chi-squared, p < 0.02) and was not related to the side of tumor, the age and sex of the patient, or the surgical approach. In a comparison among tumor groups matched for size, no statistically significant difference in facial nerve outcome between the translabyrinthine and retrosigmoid approaches was detected. The proximal facial nerve stimulation threshold at the end of surgical removal was predictive of long-term facial nerve function (analysis of variance, p < 0.02). At 1 year, 98% (87 of 89) of the patients with electrical thresholds of 0.2 V or less had grade 1 or 2 facial nerve function compared with only 50% (8 of 16) of those with thresholds between 0.21 and 0.6 V. In the era of cranial nerve monitoring, patients can be better advised about long-term facial nerve outcome after surgical intervention. Preoperatively, the size of the tumor is the most critical factor in predicting long-term facial function. Postoperatively, the proximal seventh nerve stimulation threshold at the end of the surgical procedure can be used as one prognostic measure of long-term facial nerve function.

CLINICAL CORRELATES OF ACOUSTIC NEUROMA VOLUME

A computer-assisted, MRI-based technique of tumor volume determination was used to correlate preoperative hearing levels and long-term postoperative facial function with acoustic neuroma volume. Preoperative hearing was studied in a group of 41 patients subjected to direct tumor volume calculations and in another group of 131 patients in whom volume was extrapolated from the acoustic neuroma volume-diameter relation. Similarly postoperative facial function was correlated with acoustic neuroma volume in another 864 patients in whom long-term follow-up was available. Preoperative hearing levels were found not to be significantly related to tumor volume. However, postoperative facial function was significantly associated with tumor volume and was best predicted as a nonlinear function of diameter. Thus, tumor volume changes are important considerations in the clinical management of acoustic neuromas. Patients should be advised that even small changes in tumor diameter (especially in larger tumors) can result in tumor volume changes that may be associated with significant changes in postoperative facial function.

Predicting long-term facial nerve outcome after acoustic neuroma surgery.

Although anatomic preservation of the facial nerve is achieved in nearly 90% of reported cases after acoustic neuroma surgery, postoperative long-term facial function is of most concern to the patient. This study examines long-term facial nerve function in relation to the immediate postoperative function and the function at time of discharge from the hospital. Subjects included 515 patients who underwent primary acoustic neuroma removal at House Ear Clinic from 1982 through 1989 and who had normal preoperative facial function, an intact facial nerve after surgery, and a House-Brackmann facial nerve grade available immediately postoperatively, at time of hospital discharge, and at least 1 year postoperatively. Rate of acceptable facial function (House grades I-IV) differed significantly (p < or = 0.001) at the three postoperative time intervals: 85.2%, immediate; 73.6%, discharge; 93.8%, long-term. Of those with good immediate function (grades I-II), 98.6% had acceptable long-term function. Of those with poor immediate function (grades V-VI), 69.8% had acceptable long-term function. We conclude that facial nerve recovery after acoustic neuroma surgery is characterized by slight deterioration in the immediate postoperative period, but subsequent improvement in the long-term. Patients can be reliably counseled that acceptable function immediately after surgery is associated with a favorable long-term outcome; poor function immediately after surgery, despite an intact nerve, has a more guarded prognosis.

Acoustic tumour volume and the prediction of facial nerve functional outcome from intraoperative monitoring.

The long-term facial function in 26 patients undergoing surgery to remove an acoustic neuroma has been related to the tumour volume (ml) estimated by computerized tomogram (CT) reconstruction techniques. Analysis of data allowed accurate categorization into 'small' (= < 5 ml) and 'large' (> 5 ml) tumours, which gave the maximum prognostic distinction between two groups for facial recovery. Thus, of the 14 patients with small volume tumours, 11 achieved a good (House grade I or II) facial outcome compared with 1 out of 12 patients with large tumours. Combined with the information derived from the assessment of intraoperative facial nerve electrical integrity using a combined nerve stimulator and EMG monitor, long-term facial function was predictable for all small tumours defined by volume. This represented a 15% improvement in prediction of facial recovery when defining tumour size by maximum linear dimension (small = < 2.5 cm, large > 2.5 cm). The calculations of volume obtained using a simplified ellipsoidal model compared well with CT reconstructed values (r2 = 0.85), and gave identical prediction and outcome comparisons.

The Facial Nerve in the Infratemporal Approach

A new method of re-routing the facial nerve in the infratemporal fossa approach is presented. Exposure of the skull base is not compromised and better immediate and long-term facial function is achieved. A consecutive series of 31 cases is discussed.