Residual and recurrent acoustic neuroma in hearing preservation procedures: neuroradiologic and surgical findings

Salvage Management of Vestibular Schwannoma

The current management of vestibular schwannomas (VS) includes observation, microsurgery (MS), and stereotactic radiosurgery (SRS) or radiotherapy, and treatment failures may occur with any primary modality. SRS is most often used for microsurgical failures, as it carries a low risk of adverse events. Salvage MS following previous MS is reserved for specific cases and can present certain surgical challenges. Irradiation failures can be managed with both salvage MS and repeat SRS. This article is intended to review an approach to the failure of primary interventions for VS, with a focus on the time interval between modalities, rates of tumor control, functional outcomes, and possible complications.

Hearing After Vestibular Schwannoma Surgery: Is It Preserved Forever?

INTRODUCTION

Currently, it is possible to preserve the auditory nerve in a large number of cases, but the preservation of the hearing itself is unpredictable. Apart from wait and scan strategy and stereoradiotherapy, hearing after vestibular schwannoma surgery is considered to remain stable even in long-term follow-up.

MATERIALS AND METHODS

Twenty-eight patients had preserved hearing after retrosigmoid suboccipital microsurgery of the vestibular schwannoma between 2008 and 2014. A standard audiological protocol was performed together with an magnetic resonance imaging evaluation of the fluid content of the inner ear.

RESULTS

The mean difference in pure-tone average between the direct and final postsurgical examination was 12.758 dB ( p = 2.5E - 06). The word recognition score deteriorated by 17.45% ( p = 0.03516). The mean American Academy of Otolaryngology-Head and Neck Surgery score on the second examination was 2.5, and that on the second examination was 3.111 ( p = 0.00483). There was no significant deterioration in the healthy ear.The signal intensity ratio in the basal turn of the cochlea increased by an average of 0.13 points ( p < 0.05).Patients with persistent tumor or nodular enhancement in the internal acoustic meatus deteriorated significantly in hearing according to the American Academy of Otolaryngology-Head and Neck Surgery scale compared with patients without any finding in the meatus ( p = 0.01299).

CONCLUSIONS

There is a discrete but gradual deterioration of the hearing in the postoperative period. Hearing impairment is more pronounced in patients with a nodular process in the internal acoustic meatus, regardless of whether it is growth active. After surgery, the pathological content of the inner ear normalizes (evaluated on T2 magnetic resonance imaging sequences).

A prediction model for recurrence after translabyrinthine surgery for vestibular schwannoma: toward personalized postoperative surveillance

Purpose

The aim of this study is to compute and validate a statistical predictive model for the risk of recurrence, defined as regrowth of tumor necessitating salvage treatment, after translabyrinthine removal of vestibular schwannomas to individualize postoperative surveillance.

Methods

The multivariable predictive model for risk of recurrence was based on retrospectively collected patient data between 1995 and 2017 at a tertiary referral center. To assess for internal validity of the prediction model tenfold cross-validation was performed. A ‘low’ calculated risk of recurrence in this study was set at < 1%, based on clinical criteria and expert opinion.

Results

A total of 596 patients with 33 recurrences (5.5%) were included for analysis. The final prediction model consisted of the predictors ‘age at time of surgery’, ‘preoperative tumor growth’ and ‘first postoperative MRI outcome’. The area under the receiver operating curve of the prediction model was 89%, with a C-index of 0.686 (95% CI 0.614–0.796) after cross-validation. The predicted probability for risk of recurrence was low (< 1%) in 373 patients (63%). The earliest recurrence in these low-risk patients was detected at 46 months after surgery.

Conclusion

This study presents a well-performing prediction model for the risk of recurrence after translabyrinthine surgery for vestibular schwannoma. The prediction model can be used to tailor the postoperative surveillance to the estimated risk of recurrence of individual patients. It seems that especially in patients with an estimated low risk of recurrence, the interval between the first and second postoperative MRI can be safely prolonged.

Hearing improvement after vestibular schwannoma surgery in the era of the hearing preservation rule - case report and literature review

OBJECTIVES

Hearing preservation after vestibular schwannoma (VS) surgery remains a surgical challenge. In some patients with preserved inner ear function, hearing improvement is achievable. As it is currently impossible to determine which patients will present this outcome, predictions must rely on previously published reports. Our case report describes a patient who experienced hearing improvement from an unuseful level to a useful one after vestibular schwannoma surgery.

METHODS

Surgery was performed via suboccipital retrosigmoid approach. The patient underwent a basic audiovestibular protocol before and after the surgery - pure tone and speech audiometry, otoacoustic emissions, auditory brainstem responses, electronystagmography - together with a detailed questionnaire study. Usefulness of hearing was evaluated using the AAO-HNS guidelines, supplemented by a frequency of 4 kHz.

RESULTS

Hearing was preserved and even improved from an unuseful level to a useful one. Based on the available literature, the most informative predictive factors for such a result seem to be: sudden sensorineural hearing loss prior to surgery, elicitable otoacoustic emissions and the origin from the superior vestibular nerve.

CONCLUSION

There are a limited number of studies on this topic and it is still impossible to regularly improve hearing in properly selected patients. Furthermore, the importance of postoperative hearing quality compared to other symptoms and complications remains debatable.

A critical comparison between the semisitting and the supine positioning in vestibular schwannoma surgery: subgroup analysis of a randomized, multicenter trial

OBJECTIVE

Patient positioning in vestibular schwannoma (VS) surgery is a matter of ongoing discussion. Factors to consider include preservation of cranial nerve functions, extent of tumor resection, and complications. The objective of this study was to determine the optimal patient positioning in VS surgery.

METHODS

A subgroup analysis of a randomized, multicenter trial that investigated the efficacy of prophylactic nimodipine in VS surgery was performed to investigate the impact of positioning (semisitting or supine) on extent of resection, functional outcomes, and complications. The data of 97 patients were collected prospectively. All procedures were performed via a retrosigmoid approach. The semisitting position was chosen in 56 patients, whereas 41 patients were treated while supine.

RESULTS

Complete resection was obtained at a higher percentage in the semisitting as compared to the supine position (93% vs 73%, p = 0.002). Logistic regression analysis revealed significantly better facial nerve function in the early postoperative course in the semisitting group (p = 0.004), particularly concerning severe facial nerve paresis (House-Brackmann grade IV or worse; p = 0.002). One year after surgery, facial nerve function recovered. However, there was still a tendency for better facial nerve function in the semisitting group (p = 0.091). There were no significant differences between groups regarding hearing preservation rates. Venous air embolism with the necessity to terminate surgery occurred in 2 patients in the semisitting position (3.6%). Supplementary analysis with a 2-tailed permutation randomization with 10,000 permutations of treatment choice and a propensity score matching showed either a tendency or significant results for better facial nerve outcomes in the early postoperative course and extent of resection in the semisitting group.

CONCLUSIONS

Although the results of the various statistical analyses are not uniform, the data indicate better results concerning both a higher rate of complete removal (according to the intraoperative impression of the surgeon) and facial nerve function after a semisitting as compared to the supine position. These advantages may justify the potential higher risk for severe complications of the semisitting position in VS surgery. The choice of positioning has to consider all individual patient parameters and risks carefully.

Radiosurgery treatment is associated with improved facial nerve preservation versus repeat resection in recurrent vestibular schwannomas

BACKGROUND

Vestibular schwannomas (VSs) are benign neoplasms of the Schwann cells of cranial nerve VIII, and treatment of VS typically involves surgical resection. However, tumor recurrence may necessitate reintervention, and secondary treatment modalities include repeat surgical resection or adjuvant radiosurgery. The purpose of this study is to examine the scientific literature in order to determine whether surgical resection or radiosurgery for recurrent VS results in better tumor control, hearing preservation, and preservation of facial nerve function.

METHODS

The PubMed, Scopus, Embase, Cochrane, and Web of Science databases were searched for studies reporting on patients undergoing either radiosurgery or repeat surgical resection after primary surgical resection for recurrent VS. Statistical analyses were performed on the compiled data, primarily outcome data involving tumor control, hearing preservation, and preservation of facial nerve function.

RESULTS

We analyzed the data of 15 individual studies involving 359 total patients, and our results reveal that tumor control rates are comparable between adjuvant radiosurgery (91%, CI: 88-94%) and secondary resection (92%, CI 75-98%). However, adjuvant radiosurgery was shown to preserve good facial nerve function better (94%, CI 84-98%) compared to secondary surgical resection (56%, CI 41-69%).

CONCLUSION

With comparable tumor control rates and better preservation of good facial nerve function, this study suggests that secondary radiosurgery for recurrent VS is associated with both optimal tumor control and preservation of good facial nerve function.

Surgical treatment of acoustic neuroma: Outcomes and indications

AIM

Surgery for acoustic neuroma has developed over the years with a gradual improvement in outcome. The goal of surgery should be cure of the disease and a low morbidity, preserving facial nerve function - and hearing, too, whenever feasible (i.e. in small tumors). The most appropriate approach must be decided case by case.

BACKGROUND

Results of microsurgery remain heterogeneous, however, probably due to the different amount of experience gained at different centers.

MATERIALS AND METHODS

Surgical series reported in the recent literature (2012-2015) were critically reviewed, along with some older papers with particularly representative series.

RESULTS AND CONCLUSION

Considering patients' age, surgical morbidity of different approaches, tumor size and hearing, some principles can be identified on which to base surgical indications with a view to achieving the goals of curing the disease with a low morbidity, preserving facial nerve function and hearing, too, whenever feasible (i.e. in patients with small tumors). Different therapeutic approaches are discussed.

Surveillance after resection of vestibular schwannoma: measurement techniques and predictors of growth

OBJECTIVES

To compare different methods of measuring tumor growth after resection of vestibular schwannoma and to identify predictors of growth.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center, inpatient surgery with ambulatory follow-up.

PATIENTS

All patients who underwent vestibular schwannoma resection by the senior author from September 1991 to April 2012 and had two or more postoperative MRI scans.

INTERVENTIONS

Vestibular schwannoma resection. Measurement of tumor size and enhancement pattern on postoperative magnetic resonance imaging scans.

MAIN OUTCOME MEASURES

Tumor size as measured in one (linear), two (planar), and three (volumetric) dimensions using standard radiology workstation tools versus time elapsed since surgical resection.

RESULTS

Eighty-eight patients were included with mean follow-up of 3.9 years. Linear measurement of tumor size was found to have modest correlation with planar and volumetric measurements. Excellent correlation was found between the planar and volumetric methods. Nodular enhancement increased risk for tumor growth (OR 6.25, p = 0.03 on planar analysis). If there was growth, tumors with nodular enhancement typically showed increase in size beginning 2 years postoperatively, whereas those with linear or no enhancement were typically stable in size through 5 years. Younger age and larger preoperative tumor size were also risk factors for growth (OR 0.9/p = 0.01 and OR 1.09/p = 0.02).

CONCLUSION

Simple planar measurement is an efficient method that correlates well with the more time-consuming volumetric method. The major risk factor for tumor growth is nodular enhancement on a baseline scan, a finding that warrants annual MRI beginning 2 years postoperatively. Younger age and larger preoperative size minimally increased risk of growth.

Long-term outcome of gamma knife radiosurgery for vestibular schwannoma

Objective We evaluated the long-term outcome of vestibular schwannoma (VS) treated with gamma knife radiosurgery (GKRS) as a primary treatment as well as an adjunct therapy. Materials and Methods We performed a retrospective review (2000-2012) of 82 patients with VS who received GKRS. Of 82 patients, 20 patients with prior resection received GKRS treatment as an adjunct therapy. The remainder of the patients (62) received GKRS as a primary treatment. Results GKRS for VS showed significant variations in tumor growth control (decreased in 44 patients [54%], arrested growth in 30 patients [36%], and increased tumor size in 8 patients [10%]). Progression-free survival rates after GKRS at 3, 5, and 10 years were 98%, 95%, and 95%, respectively. Hearing, facial nerve function, and Karnofsky performance scale were significantly improved after GKRS compared with pretreated status (79 versus 90). Two patients (2.5%) required resection again due to tumor progression and worsening of signs and symptoms. Conclusion Long-term follow-up demonstrated that GKRS offers a high rate of tumor control, preservation of multiple nerve functions, and a good quality of life in both new and recurrent patients with VS.

Rate of recurrent vestibular schwannoma after total removal via different surgical approaches

OBJECTIVES

The objective of this study was to assess the differences in the recurrence rates of vestibular schwannoma (VS) after total tumor removal through enlarged translabyrinthine (ETL), retrosigmoid (RS), and middle cranial fossa (MCF) approaches. Our results were compared with previously published data, and literature reviews were done to identify the possible causes for the recurrence of VS.

METHODS

We performed a retrospective analysis of 2,400 cases of VS that underwent removal at the Gruppo Otologico, Piacenza, Italy, from 1983 until 2010. The minimum postoperative follow-up was 12 months. We also reviewed the previously published data on recurrence rates of VS after ETL, RS, and MCF approaches.

RESULTS

Total tumor removal was achieved in 2,252 cases (93.8%). The recurrence rate was 0.05% for the ETL approach, 0.7% for the RS approach, and 1.8% for the MCF approach. Literature reviews of 3 previously published case series utilizing the translabyrinthine approach showed that none of the primary tumors were less than 2.0 cm in size. Recurrences were seen between 1 and 13 years after the initial surgery.

CONCLUSIONS

The rate of VS recurrence after total removal is exceptionally low in experienced hands. Undetected microscopic deposits left on crucial points such as the facial nerve, the preserved cochlea nerve, or the fundus of the internal auditory canal could be possible causes for the recurrence. A definite advantage of an ETL approach is the excellent internal auditory canal exposure, resulting in an extremely low rate of VS recurrence. The patients should be followed up to 15 years with gadolinium-enhanced magnetic resonance imaging (with fat suppression sequence in ETL approach cases). Recurrent VS may exhibit a faster growth rate than primary VS.

Nodular enhancement within the internal auditory canal following retrosigmoid vestibular schwannoma resection: a unique radiological pattern

Object

The authors describe the unique occurrence of nodular enhancement within the fundus of the internal auditory canal (IAC) lateral to the preoperative radiological tumor margin following gross-total vestibular schwannoma (VS) resection.

Methods

The nature of the study was a retrospective chart review of records. The authors reviewed the cases of all patients who underwent microsurgical resection of a VS between January 2000 and January 2010 at a single tertiary referral center. Patients with incomplete resection, neurofibromatosis Type 2, and those with fewer than 2 postoperative MR images available for review were excluded.

Postsurgical patients with IAC enhancement located lateral to the preoperative imaging–delineated tumor margin were identified. Lesion morphology was characterized on serial MR imaging studies. Clinical follow-up and outcomes were recorded.

Results

Over the past decade, 350 patients underwent microsurgical VS resection. Of these, 16 patients met study criteria and were found to have postsurgical enhancement in the distal aspect of the IAC lateral to the imaging limits of the preoperative tumor margin on the first postoperative MR imaging study (37.5% women, median age 45 years). Initial MR imaging was performed at a mean of 3.1 months following surgery, and the mean radiological follow-up duration was 39.8 months (range 16.4–101.9 months). None of the 16 patients developed recurrence during the follow-up course.

Conclusions

In contrast to previous publications that have reported a high rate of recurrence in cases involving nodular enhancement within the original tumor bed, postoperative enhancement in the IAC lateral to the original tumor margin appears to carry much less risk for tumor recurrence. These findings may be helpful when counseling patients on the recommended frequency of postoperative follow-up imaging.

Fast-growing vestibular schwannoma

A case of a Jehovah's witness affected by an intracanalicular vestibular schwannoma with an extremely fast growth rate is presented. Nine months after presentation, the tumor reached 23 mm in the cerebellopontine angle. A partial removal through a retrosigmoid approach was planned. Because of the presence of a dominant high jugular bulb masquering the internal auditory canal, the intracanalicular portion of the tumor was left in place. The residual tumor grew 12 mm in 2 months. Even after a gross total removal through a middle cranial fossa approach, the tumor recurred, reaching the size of 30 mm in 17 months. A modified transcochlear approach was then performed, and the patient was free of disease at the last radiologic follow-up, 8 months after the surgery. We illustrate our strategy in treating this aggressive benign lesion with unusual behavior.

Long-term outcomes in patients with vestibular schwannomas treated using gamma knife surgery: 10-year follow up

Object. Gamma knife surgery (GKS) has been a safe and effective treatment for vestibular schwannomas in both the short and long term, although less is known about long-term outcomes in the past 10 years. The aim of this study was to clarify long-term outcomes in patients with vestibular schwannomas treated using GKS based on techniques in place in the early 1990s.

Methods. Eighty patients harboring a vestibular schwannoma (excluding neurofibromatosis Type 2) were treated using GKS between May 1991 and December 1993. Among these, 73 patients were assessed; seven were lost to follow up. The median duration of follow up was 135 months. The mean patient age at the time of GKS was 56 years old. The mean tumor volume was 6.3 cm3, and the mean maximal and marginal radiation doses applied to the tumor were 28.4 and 14.6 Gy, respectively. Follow-up magnetic resonance images were obtained in 71 patients. Forty-eight patients demonstrated partial tumor remission, 14 had tumors that remained stable, and nine demonstrated tumor enlargement or radiation-induced edema requiring resection. Patients with larger tumors did not fare as well as those with smaller lesions. The actuarial 10-year progression-free survival rate was 87% overall, and 93% in patients with tumor volumes less than 10 cm3. No patient experienced malignant transformation.

Conclusions. Gamma knife surgery remained an effective treatment for vestibular schwannomas for longer than 10 years. Although treatment failures usually occurred within 3 years after GKS, it is necessary to continue follow up in patients to reveal delayed tumor recurrence.

Enlarged translabyrinthine approach for the management of large and giant acoustic neuromas: a report of 175 consecutive cases

The translabyrinthine approach was once considered inadequate for the removal of acoustic neuromas (ANs), but that theory has few proponents today. Over the years, the translabyrinthine approach has been modified into the enlarged translabyrinthine approach, with experience and technical refinements leading to a wider access. Between April 1987 and December 2001, the Gruppo Otologico of Piacenza-Rome was able to remove 175 ANs 3 cm or larger in size from the cerebellopontine angle by adopting this modified surgical technique. These tumors represented 24.7% of all 707 ANs for which surgery was performed during the same period of time. Among the 175 cases, there was only 1 death. The incidence of complications was very low and was comparable to results previously published in the literature. Consequently, the hospital stay was short, with a mean of 7.3 days (5.1 days in the last 45 cases). The preoperative ipsilateral hearing was already compromised in 119 of the 175 cases (68%; class C/D according to the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology-Head and Neck Surgery, 1995). From our results, we can conclude that the use of the enlarged translabyrinthine approach in AN surgery is not dependent on tumor size. On the contrary, the advantages of a low rate of morbidity and a short hospital stay are ample proof that this is the best approach for the removal of large ANs.

Comparison of management options for patients with acoustic neuromas

Management options for patients with vestibular schwannomas (acoustic neuromas) include observation, tumor resection, stereotactic radiosurgery, and fractionated radiotherapy. In this report the authors review their 15-year experience with radiosurgery and discuss indications and expectations in relation to the different approaches. They conducted a survey of neurosurgeons to determine management preferences in two different cases of intra- and extra-canalicular tumor presentations. Patient decisions must be based on quality information derived from peer-reviewed literature.

Treatment of residual vestibular schwannoma

OBJECTIVE

To evaluate the results of the surgical removal of residual vestibular schwannomas and compare them with results obtained from the first operation.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary otologic and skull base referral center. PATIENTS Twenty-three patients with residual vestibular schwannoma from a total of 637 patients who underwent surgery during the same time (April 1987 to April 2001). Only 1 patient had previously been treated in the same center. All but 1 patient had previously undergone at least 1 retrosigmoid approach. The majority of patients experienced an extensive list of complications and additional treatments after the first operation. Only 2 patients experienced some measurable hearing preoperatively. Previous hospitalization averaged 34.9 days, with a minimum of 5 and a maximum of 150 days.

INTERVENTIONS

16 patients were treated through an enlarged translabyrinthine approach and 7 through a modified transcochlear approach.

MAIN OUTCOME MEASURES

Total tumor removal, postoperative complications, hospital stay.

RESULTS

All but 2 patients underwent a total removal. Complications recorded were 1 temporary hemiparesis and aphasia, 1 subcutaneous abdominal hematoma, and 2 transitory VIth cranial nerve palsies. No additional treatment was required. The postoperative hospital stays ranged from 3 to 22 days, with a mean of 6.9.

CONCLUSIONS

Patients with vestibular schwannoma should be treated by an experienced team in a referral center to reduce postoperative morbidity and decrease the need to resort to only partial removal. Planned subtotal removal should be reserved for a few selected cases. The retrosigmoid approach is considered to have the highest risk that tumor remnants will unintentionally be left. In surgery of a residual vestibular schwannoma that has previously been treated through the retrosigmoid approach, the translabyrinthine approach offers some advantages with respect to performing another retrosigmoid procedure. In the presence of long-lasting facial palsy, the modified transcochlear approach represents the safest and most viable option available.

Retrosigmoid approach for small and medium-sized acoustic neuromas

OBJECTIVE

Clinical study of the keyhole acoustic neuroma retrosigmoid approach for facial nerve and hearing preservation.

STUDY DESIGN

This was a prospective case review from October 1993 to December 1998 in a referral hospital care unit.

PATIENTS

A total of 119 consecutive patients with a tumor size of <25 mm in the cerebellopontine angle corrected by a retrosigmoid approach were included in the study.

INTERVENTIONS

Standard audiometric and imaging assessments, complete tumor removal by using endoscopy-assisted control, and nerve monitoring.

MAIN OUTCOME MEASURES

House-Brackmann facial nerve grade and hearing level by the American Academy of Otolaryngology-Head and Neck Surgery classification.

RESULTS

Grades I and II facial nerve function was obtained in 96% of cases, measurable hearing was preserved in 49% of cases, and 30% of cases achieved serviceable hearing.

CONCLUSION

The retrosigmoid approach is a safe and reliable approach in random patients with small and medium-sized acoustic neuromas.

Acoustic Neuromas

Patients with acoustic neuromas have several treatment options that include observation, surgical resection, stereotactic radiosurgery, and fractionated radiotherapy. Resection is indicated for patients with larger tumors that have caused major neurologic deficits from brain compression. Surgeons perform stereotactic radiosurgery as the main alternative to acoustic tumor resection with the goals of preserved neurologic function and prevention of tumor growth. The long-term outcomes of radiosurgery, particularly with gamma knife technique, have proven its role in the primary or adjuvant management of this disease. Radiotherapy can be offered to selected patients with larger tumors in whom radiosurgery may not be feasible. Patients with neurofibromatosis type-2 pose specific challenges, particularly in regard to preservation of hearing and other cranial nerve function. The primary clinical issues include avoiding tumor-related or treatment-related mortality, prevention of further tumor-related neurologic disability, minimizing treatment risks such as spinal fluid leakage, infections, or cardiopulmonary complications, maintaining regional cranial nerve function (facial, trigeminal, cochlear, and glossopharyngeal/vagal), avoiding hydrocephalus, maintaining quality of life and employment, and reducing cost. All treatment choices should strive to meet all of these goals.

[Trans-labyrinthine approach for the resection large and giant acoustic nerve neuromas]

The standard translabyrinthine approach for acoustic neuromas removal was introduced by W. House in 1964. After several years of experience the original translabyrinthine approach has been progressively modified into the current "enlarged" approach by extending the area of bone removal. This increased surgical field has made the translabyrinthine approach suitable for the removal of tumours of all sizes. We present our serie of 71 large (52) and giant (19) neuromas of the VIIIth nerve removed through a translabyrinthine approach between 1993 and 1998 at the ENT Department of Legnano.

Conventionally fractionated stereotactic radiotherapy (FSRT) for acoustic neuromas

PURPOSE

Analysis of local tumor control and functional outcome following conventionally fractionated stereotactic radiotherapy (FSRT) for acoustic neuromas.

PATIENTS AND METHODS

From 11/1989 to 9/1999 51 patients with acoustic neuromas have been treated by FSRT. Mean total dose was 57.6 +/- 2.5 Gy. Forty-two patients have been followed for at least 12 months and were subject of an outcome analysis. Mean follow-up was 42 months. We analyzed local control, hearing preservation, and facial and trigeminal nerve functional preservation. We evaluated influences of tumor size, age, and association with neurofibromatosis Type 2 (NF2) on outcome and treatment related toxicity.

RESULTS

Actuarial 2- and 5-year tumor control rates were 100% and 97.7%, respectively. Actuarial useful hearing preservation rate was 85% at 2 and 5 years. New hearing loss was diagnosed in 4 NF2 patients. Pretreatment normal facial nerve function was preserved in all cases. Two cases of new or impaired trigeminal nerve dysesthesia required medication. No other cranial nerve deficit was observed. In Patients without NF2 tumor size or age had no influence on tumor control and cranial nerve toxicity. Diagnosis of NF2 was associated with higher risk of hearing impairment (p = 0.0002), the hearing preservation rate in this subgroup was 60%.

CONCLUSION

FSRT has been shown to be an effective means of local tumor control. Excellent hearing preservation rates and 5th and 7th nerve functional preservation rates were achieved. The results support the conclusion that FSRT can be recommended to patients with acoustic neuromas where special attention has to be taken to preserve useful hearing and normal cranial nerve function. For NF2 patients, FSRT may be the treatment of choice with superior functional outcome compared to treatment alternatives.

Stereotactic radiosurgery for tumor-related trigeminal pain

OBJECTIVE

Between 1 and 6% of patients who are diagnosed with facial pain syndromes have tumors that involve the trigeminal nerve. We report the effects of stereotactic radiosurgery on tumor-related trigeminal pain.

METHODS

We reviewed results, from a prospective database, for 24 consecutive patients with cranial base tumors and either trigeminal neuralgia (n = 9) or painful trigeminal neuropathy (n = 15) who underwent stereotactic radiosurgery during an 8-year period. The tumor was the radiosurgical target for these patients (not the trigeminal nerve or ganglion). The median clinical follow-up period after radiosurgery was 45 months (range, 12-90 mo); the median neuroimaging follow-up period was 36 months (range, 5-86 mo).

RESULTS

There were 20 women and 3 men, with an average age of 57 years (range, 33-79 yr). One patient had bilateral facial pain and underwent staged radiosurgery. Pathological classification indicated 16 meningiomas and 8 malignant cranial base tumors (adenoid cystic carcinoma, n = 6; squamous cell carcinoma, n = 2). Twelve of 24 patients (50%) were initially free of pain, and another 11 patients (46%) reported that they experienced significant improvements in their trigeminal pain syndromes after radiosurgery. The tumor histological type, quality of facial pain, preexisting facial numbness, and marginal and maximal radiation doses were not related to postradiosurgical facial pain outcomes. Three patients with malignant cranial base carcinomas developed recurrent facial pain, 1 to 9 months after radiosurgery, which was related to tumor progression outside the irradiated volume. One patient (4%) developed new partial V2 numbness after radiosurgery.

CONCLUSION

Radiosurgery proved to be effective in improving tumor-related trigeminal pain for the majority of patients with either benign or malignant cranial base tumors. Recurrence of trigeminal pain is frequent for patients with malignant cranial base carcinomas and is related to tumor progression.

Stereotactic radiosurgery in the management of acoustic neuromas associated with neurofibromatosis Type 2

OBJECT

Stereotactically guided radiosurgery is one of the primary treatment modalities for patients with acoustic neuromas (vestibular schwannomas). The goal of radiosurgery is to arrest tumor growth while preserving neurological function. Patients with acoustic neuromas associated with neurofibromatosis Type 2 (NF2) represent a special challenge because of the risk of complete deafness. To define better the tumor control rate and long-term functional outcome, the authors reviewed their 10-year experience in treating these lesions.

METHODS

Forty patients underwent stereotactic radiosurgery at the University of Pittsburgh, 35 of them for solitary tumors. The other five underwent staged procedures for bilateral lesions (10 tumors, 45 total). Thirteen patients (with 29% of tumors) had undergone a median of two prior resections. The mean tumor volume at radiosurgery was 4.8 ml, and the mean tumor margin dose was 15 Gy (range 12-20 Gy). The overall tumor control rate was 98%. During the median follow-up period of 36 months, 16 tumors (36%) regressed, 28 (62%) remained unchanged, and one (2%) grew. In the 10 patients for whom more than 5 years of clinical and neuroimaging follow-up results were available (median 92 months), five tumors were smaller and five remained unchanged. Surgical resection was performed in three patients (7%) after radiosurgery; only one showed radiographic evidence of progression. Useful hearing (Gardner-Robertson Class I or II) was preserved in six (43%) of 14 patients, and this rate improved to 67% after modifications made in 1992. Normal facial nerve function (House-Brackmann Grade 1) was preserved in 25 (81%) of 31 patients. Normal trigeminal nerve function was preserved in 34 (94%) of 36 patients.

CONCLUSIONS

Stereotactically guided radiosurgery is a safe and effective treatment for patients with acoustic tumors in the setting of NF2. The rate of hearing preservation may be better with radiosurgery than with other available techniques.

Stereotactic radiosurgery in the management of acoustic neuromas associated with neurofibromatosis Type 2

Object

Stereotactically guided radiosurgery is one of the primary treatment modalities for patients with acoustic neuromas (vestibular schwannomas). The goal of radiosurgery is to arrest tumor growth while preserving neurological function. Patients with acoustic neuromas associated with neurofibromatosis Type 2 (NF2) represent a special challenge because of the risk of complete deafness. To better define the tumor control rate and long-term functional outcome, the authors reviewed their 10-year experience in treating these lesions.

Methods

Forty patients underwent stereotactic radiosurgery at the University of Pittsburgh, 35 of them for solitary tumors. The other five underwent staged procedures for bilateral lesions (10 tumors, 45 total). Thirteen patients (with 29% of tumors) had undergone a median of two prior resections. The mean tumor volume at radiosurgery was 4.8 ml and the mean tumor margin dose was 15 Gy (range 12–20 Gy).

The overall tumor control rate was 98%. During the median follow-up period of 36 months, 16 (36%) tumors regressed, 28 (62%) remained unchanged, and one (2%) grew. In the 10 patients for whom more than 5 years of clinical and neuroimaging follow-up results were available (median 92 months), five tumors were smaller and five remained unchanged. Surgical resection was performed in three patients (7%) after radiosurgery; only one showed radiographic evidence of progression. Useful hearing (Gardner-Robertson Class I or II) was preserved in six (43%) of 14 patients and this rate improved to 67% after modifications made in 1992. Normal facial nerve function (House-Brackmann Grade 1) was preserved in 25 (81%) of 31 patients. Normal trigeminal nerve function was preserved in 34 (94%) of 36 patients.

Conclusions

Stereotactically guided radiosurgery is a safe and effective treatment for patients with acoustic tumors in the setting of NF2. The rate of hearing preservation may be better with radiosurgery than with other available techniques.

Vestibular schwannoma management. Part I. Failed microsurgery and the role of delayed stereotactic radiosurgery

OBJECT

The purpose of this study was to analyze patient outcomes and to define the role of radiosurgery in patients who have undergone prior microsurgical resection of their vestibular schwannoma.

METHODS

The authors evaluated the pre- and postoperative clinical and neuroimaging characteristics of 76 consecutive patients with 78 vestibular schwannomas who underwent radiosurgery after previous surgical resection. Twenty-nine patients (37% of tumors) had undergone more than one prior resection. Forty-three patients (55% of tumors) had significant impairment of facial nerve function (House-Brackmann Grades III-VI) after their microsurgical procedure; 50% had trigeminal sensory loss, and 96% had poor speech discrimination (< 50%). The median evaluation period following radiosurgery was 43 months (range 12-101 months). Tumor growth control after radiosurgery was achieved in 73 tumors (94%). Six patients underwent additional surgical resection despite radiosurgery (median of 32 months after radiosurgery), and one patient underwent repeated radiosurgery for tumor progression outside the irradiated volume. Eleven (23%) of 47 patients with Grades I to III facial function before radiosurgery developed increased facial weakness after radiosurgery. Eleven patients (14%) developed new trigeminal symptoms.

CONCLUSIONS

Radiosurgery proved to be a safe and effective alternative to additional microsurgery in patients in whom the initial microsurgical removal failed. Stereotactic radiosurgery should be considered for all patients who have regrowth or progression of previously surgically treated vestibular schwannomas.

Long-term outcomes after radiosurgery for acoustic neuromas

BACKGROUND

Stereotactic radiosurgery is the principal alternative to microsurgical resection for acoustic neuromas (vestibular schwannomas). The goals of radiosurgery are the long-term prevention of tumor growth, maintenance of neurologic function, and prevention of new neurologic deficits. Although acceptable short-term outcomes have been reported, long-term outcomes have not been well documented.

METHODS

We evaluated 162 consecutive patients who underwent radiosurgery for acoustic neuromas between 1987 and 1992 by means of serial imaging tests, clinical evaluations, and a survey between 5 and 10 years after the procedure. The average dose of radiation to the tumor margin was 16 Gy, and the mean transverse diameter of the tumor was 22 mm (range, 8 to 39). Resection had been performed previously in 42 patients (26 percent); in 13 patients the tumor represented a recurrence of disease after a previous total resection. Facial function was normal in 76 percent of the patients before radiosurgery, and 20 percent had useful hearing.

RESULTS

The rate of tumor control (with no resection required) was 98 percent. One hundred tumors (62 percent) became smaller, 53 (33 percent) remained unchanged in size, and 9 (6 percent) became slightly larger. Resection was performed in four patients (2 percent) within four years after radiosurgery. Normal facial function was preserved in 79 percent of the patients after five years (House-Brackmann grade 1), and normal trigeminal function was preserved in 73 percent. Fifty-one percent of the patients had no change in hearing ability. No new neurologic deficits appeared more than 28 months after radiosurgery. An outcomes questionnaire was returned by 115 patients (77 percent of the 149 patients still living). Fifty-four of these patients (47 percent) were employed at the time of radiosurgery, and 37 (69 percent) remained so. Radiosurgery was believed to have been successful by all 30 patients who had undergone surgery previously and by 81 (95 percent) of the 85 who had not. Thirty-six of the 115 patients (31 percent) described at least one complication, which resolved in 56 percent of those cases.

CONCLUSIONS

Radiosurgery can provide long-term control of acoustic neuromas while preserving neurologic function.

Outcomes after gamma knife radiosurgery in solitary acoustic tumors and neurofibromatosis Type 2

Surgeons perform stereotactic radiosurgery as the main alternative to acoustic tumor (vestibular schwannoma) resection. The goals of radiosurgery include preservation of neurological function and prevention of tumor growth. Longer-term outcomes are not well documented for patients with solitary tumors or those with neurofibromatosis Type 2 (NF2).

To define outcomes, the authors evaluated 462 consecutive patients with solitary acoustic tumors and 40 patients with NF2 (total of 45 tumors treated) who underwent radiosurgery between 1987 and 1998.

Serial imaging studies, clinical evaluations, and a patient survey were performed. The average tumor margin dose was 15 Gy, and the mean transverse tumor diameter was 22 mm. In patients with solitary tumors, prior resection had been performed in 111 patients (24%); 27 patients experienced tumor recurrence after a “total resection.”

The clinical tumor control rate (no resection required) was 98%. In non-NF2 patients followed for at least 5 years, 100 tumors (61.7%) were smaller, 53 (32.7%) remained unchanged in size, and nine (5.6%) were slightly larger. Resection was performed in four patients (2.4%). Neurological deficits after radiosurgery all occurred within the first 28 months. The rates of facial and trigeminal neuropathy varied with radiosurgery technique. In patients with NF2, 16 tumors were smaller, 28 remained unchanged, and one enlarged (overall 98% control rate at median 3-year follow up). Resection was performed in three patients (7%). Useful hearing was preserved in six (43%) of 14 NF2 patients who had useful hearing before radiosurgery.

Radiosurgery provided long-term tumor control associated with high rates of neurological function preservation. No further tumor surgery was necessary in 98% of patients with solitary tumors followed for a minimum of 5 years.

Vestibular schwannoma management in the next century: a radiosurgical perspective

PURPOSE

To discuss how the evolution of vestibular schwannoma radiosurgery, changes in health care delivery, and patient accessibility to medical information will affect the management of vestibular schwannomas in the future.

CONCEPT

In comparison with microsurgical resection of vestibular schwannomas, radiosurgery has a lower morbidity rate, a similar risk of requiring further surgery, and higher patient satisfaction. As this information becomes more widely available to patients and third-party payors, radiosurgery may replace surgical resection as the preferred management strategy for patients with small to medium sized vestibular schwannomas in the United States.

RATIONALE

It is estimated that 2500 patients are diagnosed with vestibular schwannomas each year in the United States. Assuming that 80% undergo surgery, 2000 operations are performed annually for newly diagnosed vestibular schwannomas. Data available since 1987 regarding the number of cases for which gamma knife radiosurgery was performed were used to predict the number of patients who will undergo vestibular schwannoma radiosurgery in the future. If the current trend continues, an equal number of patients will undergo surgical resection and radiosurgery to treat their vestibular schwannomas (approximately 1000/yr) sometime between 2005 and 2010. Moreover, it is predicted that by 2020, two-thirds of the patients who are newly diagnosed with vestibular schwannomas will undergo radiosurgery, with surgical resection being reserved for patients with large tumors associated with symptomatic brain stem compression.

DISCUSSION

Early data regarding vestibular schwannoma radiosurgery predicted an exponential growth curve. Although it is premature to assume that the current trend will continue, it is likely that an ever increasing percentage of patients will undergo radiosurgery as accessibility to this alternative increases, and more data are published regarding long-term tumor growth control rates. If the mathematical model proves to be accurate, then stereotactic radiosurgery will replace surgical resection as the preferred management strategy for the majority of patients with vestibular schwannomas.