Acoustic Neuroma

Evolving Role of Non-Total Resection in Management of Acoustic Neuroma in the Gamma Knife Era

OBJECTIVE

To examine patients with residual tumor after vestibular schwannoma (VS) resection with focus on need for further therapy, including stereotactic radiosurgery (SRS) and revision surgery.

STUDY DESIGN AND SETTING

Retrospective review at two tertiary otology referral centers.

PATIENTS AND INTERVENTION

Patients undergoing primary surgery for VS from 2007 to 2017.

MAIN OUTCOME MEASURE

Degree of resection and need for further treatment.

RESULTS

Of 289 patients undergoing surgery, 38 (13.1%) underwent subtotal resections (<95% of tumor resected) and 77 (26.6%) underwent near-total resections (≥95% but <100%). Patients with any residual tumor had larger tumors preoperatively (mean estimated volume 6.3 cm versus 2.1 cm, p < 0.0005) but were otherwise clinically and demographically similar to the population as a whole. Further treatment (surgery or SRS) was needed in 4.6, 14.3, and 50.0% of patients after gross total, near-total, and subtotal resections, respectively (p < 0.0005). Patients undergoing additional therapy had larger residual tumors (median post- to preoperative estimated volume ratio 0.09 versus 0.01, p < 0.0005). Patients undergoing subtotal and near-total resections had poorer facial function at ultimate follow up than those undergoing gross total resections (p = 0.001), likely due to larger tumors and more difficult resections. Literature review revealed higher rates of gross total resection as well as facial palsy in the pre-SRS era.

CONCLUSION

Residual tumor following VS resection is more common today than in the pre-SRS era. Availability of SRS may encourage leaving residual tumor intraoperatively to preserve neural structures. Current surgical strategies decrease surgical morbidity but necessitate further treatment in over 10% of cases.

Nonvestibular schwannomas of the brain: a 7-year experience

OBJECTIVE

Nonvestibular schwannomas are uncommon tumors of the brain. Trigeminal nerve schwannomas are the most common of this group, followed by glossopharyngeal, vagal, facial, accessory, hypoglossal, oculomotor, trochlear, and abducens nerve schwannomas, in descending order of frequency. We present a series of nonvestibular schwannomas that were surgically treated during a 7-year period.

METHODS

Forty-six patients with schwannomas of Cranial Nerves V (26 cases), VII (7 cases), IX, X, and XI (9 cases), XII (3 cases), and III (1 case) were microsurgically treated by the senior author (LNS) during a 7-year period, from 1993 to 2000. The clinical presentations, operative approaches, complications, and results were studied.

RESULTS

Forty-five patients underwent gross total tumor resection in the first operation. One patient who had undergone subtotal tumor resection in the initial operation experienced a large recurrence after 4 years, and gross total tumor resection was achieved in the second operation. There were no postoperative deaths. Postoperative morbidity consisted of cerebrospinal fluid leaks for 5 patients (3 patients required a second operation to repair the leak, and 2 patients responded to lumbar drain placement), meningitis for 3 patients (2 cases were aseptic and 1 involved bacterial meningitis, which resolved with antibiotic therapy), vasospasm requiring angioplasty for 1 patient, temporary hemiparesis for 2 patients (who experienced good recoveries), and permanent hemiparesis for 1 patient. New cranial nerve deficits were observed for 24% of patients but were usually partial. The mean follow-up period was 33.3 months (range, 0.2-93 mo). No patient experienced tumor recurrence after complete tumor removal. The patient who experienced regrowth of the tumor did not exhibit recurrence after the second operation. The Karnofsky Performance Scale scores at the latest follow-up examination were 80 or more for 45 patients (98%) and 70 for 1 patient.

CONCLUSION

Nonvestibular schwannomas can be treated via microsurgical excision, with excellent functional results. Recurrence is rare after total tumor excision, although much longer follow-up monitoring is required.

Hypoglossal-facial nerve anastomosis for facial nerve palsy following surgery for cerebellopontine angle tumors

Hypoglossal-facial nerve anastomosis is one of the procedures frequently performed to restore function after facial palsy secondary to surgery for removal of cerebellopontine angle tumors. The published results of hypoglossal-facial nerve anastomosis have been variable, and there are still questions about the indications, timing, and surgical techniques for this procedure. The goals of the present retrospective analysis of 22 cases of hypoglossal-facial nerve anastomosis were to assess the extent of the functional recovery and to analyze the factors affecting this recovery. The 22 cases of complete facial palsy were gleaned from a series of 245 cases of cerebellopontine angle tumors treated surgically by one of the authors. Twenty patients had an acoustic neuroma (average size 3.5 cm), one patient had a petrous meningioma, and one patient had a facial neuroma. The average age of the patients was 47.3 years (range 19 to 69 years). The average interval from tumor surgery to hypoglossal-facial nerve anastomosis was 6.4 months (range 12 days to 17 months), and the average follow-up period after the procedure was 65 months. The results were graded as good, fair, poor, or failure according to a new method of classifying facial nerve function after hypoglossal-facial nerve anastomosis. The results were good in 14 cases (63.6%), fair in three (13.6%), and poor in four (18.2%); one (4.5%) was a failure. Good and fair results occurred with higher frequency in younger patients who were operated on within shorter intervals, although these relationships were not statistically significant. There were no surgical complications. Good or fair results were achieved in 17 (77.3%) of the 22 cases, and thus hypoglossal-facial nerve anastomosis is considered an effective procedure for most patients with facial palsy after surgery for cerebellopontine angle tumors.

Facial nerve repair by interposition nerve graft: results in 22 patients

Resection of tumors of the posterior cranial base may incorporate a segment of the facial nerve because of tumor infiltration, or may result in unplanned nerve injury. Immediate repair of the facial nerve by resuture or with an autogenous nerve graft is highly desirable to ensure optimal recovery of facial function. Twenty-four patients who underwent extensive surgery of the posterior skull base and facial nerve reconstruction were studied. Of these, 12 patients had preoperative facial weakness and 3 had facial palsy. All patients underwent graft reconstruction from the subarachnoid or labyrinthine portion of the facial nerve to the fallopian or extracranial segment. The greater auricular nerve was used as a graft in 14 patients, and the sural nerve in 10. Two patients died of their disease soon after surgery, and, therefore, were excluded from our follow-up. In the remaining 22 patients, the median follow-up time was 20 months. As evaluated by the House-Brackmann grading system, 45% (10/22) of the surviving patients achieved a good recovery of facial function, 36% (8/22) attained a fair recovery, and 18% (4/22) had minimal or no recovery. There was no statistical correlation between the length of the graft used and the degree or timing of clinical recovery. The surgical result obtained in all patients with complete preoperative facial palsy and in one patient with dense facial paresis was poor.

Intracranial repair of interrupted facial nerve in course of operation for acoustic neurinoma by microsurgical technique

The microsurgical refinement of the lateral suboccipital approach is, in our opinion, the most satisfactory operative technique for achieving total removal of acoustic neurinomas of all sizes. In this series of 164 operated cases, large or very large tumours accounted for 64% of the cases (105 patients). The facial nerve was sacrificed in about 19% of the cases. In 81% of the cases the facial nerve was respected (65%) or repaired (16%) by direct intracranial suture performed immediately after tumour removal. Good or fair functional results were obtained in about 65% of the cases by this last procedure, which has to be considered as the treatment of choice for facial nerve repair. The results are compared with those of other series and with those obtained by different nerve substitution procedures.

[Results of 110 microsurgical acoustic neuroma operations]

We report our experiences in 110 cases of microsurgical removal of acoustic neurinomas. The historic development, the chances of preservation of the facial nerve and hearing function and the mortality risks are described in detail, hereby stressing the advantages of the lateral suboccipital approach in microneurosurgery.

Hypoglossofacial anastomosis for facial palsy after resection of acoustic neuroma

Twelve patients with facial palsy after resection of acoustic neuromas were treated by hypoglossofacial anastomosis. The nerve anastomosis were performed 1-2 months after resection of the tumor in 10 cases (group A). Two cases (group B) had the anastomosis performed more than 2 years after damage to the facial nerve. All the cases had been followed for more than 9 months. The results of reinnervation of the paralyzed facial muscles were quite satisfactory, i.e., over 80% of the cases obtained a good functional recovery. Although there was a 2-month delay in functional recovery of group B patients, the final results were practically the same in both groups. Therefore, the effect of the duration of the paralysis of the facial nerve seems to be less important in facial nerve surgery than in nerve surgery of the extremities. The procedures of anastomosis of descendens hypoglossi to the distal stump to the hypoglossal in 7 of the 10 patients using the hypoglossal as the donor nerve was of little help in prevention or restoration of the hemiatrophy of the tongue. In spite of long-term inconvenience in speaking and eating after section of the hypoglossal, all the patients were able to make enough adjustments about 2-3 months after nerve surgery.

Spinofacial anastomosis

Removal of large acoustic neuromas may still be followed by facial nerve palsy. The results of fourteen cases of spinofacial nerve anastomosis have been studied and compared with the results of spinofacial and hypoglossal-facial anastomoses reported in the literature. Other standard treatments of facial palsy have been briefly reviewed and criteria developed by which the most appropriate therapy for facial paralysis may be selected.

FACIAL NERVE PRESERVATION BY POSTERIOR FOSSA TRANSMEATAL MICRODISSECTION IN TOTAL REMOVAL OF ACOUSTIC TUMOURS

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