Results of translabyrinthine removal of 300 acoustic neuromas related to tumour size

A Retrospective Clinicoradiologic Study of 126 Cerebellopontine Angle Tumors to Predict the Outcome of House–Brackmann Status to Prognosticate Them: A Single-Center Tertiary Care Perspective

Introduction House–Brackmann (HB) grading had been described to quantify the facial nerve involvement in cerebellopontine angle (CPA) tumors, a very common tumor in neurosurgical practice. Very few studies have specifically looked into the factors predicting the facial nerve morbidity and its severity. Here, we try finding these while going through the clinicoradiologic factors and its natural course to help us prognosticate the patients.

Objective To analyze the size of tumor and duration of symptoms to predict the severity of HB status of facial nerve presentation and outcome, and to study the course of the disease to help prognosticate the patients with respect to facial nerve status.

Materials and Methods This was a retrospective analysis of 126 operated CPA tumors, where we studied the natural course of HB status with respect to size and duration of symptoms of patients at our institute between December 2016 to February 2020.

Results Average duration of symptoms were 33.8 days with increasing risk of HB outcome after 36 days of symptoms. All patients improved to their preoperative facial nerve status at 3 months and only 18 maintained the worsened HB status. Average size of tumor was 3.53 cm, and size higher than 3.8 cm was associated with poorer HB outcome.

Conclusion Although there can be a significant deterioration of HB status in immediate postoperative period, it improves to preoperative status in due time. Tumor larger than 3.8 cm and symptom duration more than 36 days are two important factors predicting poorer HB outcome.

Vestibular Schwannoma Cerebellopontine Angle Position Impacts Facial Outcome

OBJECTIVES/HYPOTHESIS

To determine the impact of vestibular schwannoma (VS) position relative to the internal auditory canal (IAC) on postoperative facial nerve function and extent of surgical resection.

STUDY DESIGN

Retrospective chart review.

METHODS

Retrospective review of patients undergoing resection of large (≥25 mm) VSs. Outcome measures included early (≤1 month) facial function, long-term (≥1 year) facial function and extent of resection. Tumor measurements included the greatest dimension, dimension anterior to the IAC axis, dimension posterior to the IAC axis, and a ratio of posterior-to-anterior dimension (PA ratio).

RESULTS

A total of 127 patients met inclusion criteria. In early follow-up, 60% patients had good (House-Brackmann I-II), and 40% patients had poor (House-Brackmann III-VI) facial function. In long-term follow-up, 71% patients had good, and 29% patients had poor facial function. A total of 72% of patients underwent gross total resection (GTR) of their tumors. Patients with good facial function had significantly larger PA ratios than patients with poor function both early and long term; however, greatest dimension was the more clearly significant independent predictor of facial outcomes. A larger PA ratio was observed in patients in whom GTR was achieved, but this association was potentially confounded by surgeon preferences and was not statistically significant after controlling for surgical site.

CONCLUSIONS

This study demonstrates that VS position relative to the IAC axis can be used along with tumor size to predict postoperative facial outcomes. A greater proportion of tumor posterior to the IAC axis was associated with significantly better facial outcomes.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Microsurgical treatment of symptomatic vestibular schwannomas in patients under 40: different results before and after age of 30

In 10-15% of cases of vestibular schwannoma (VS), age at diagnosis is 40 years or less. Little is known about the differences in natural history, surgical findings, and postoperative outcomes of such younger patients as compared to those of greater age. To analyze clinical and surgical and imaging data of a consecutive series of n = 50 patients with unilateral sporadic VS, aged 40 years or younger - separated in a very young group (15-30 years) and a moderately young group (31-40 years). Retrospective case series. Fifty consecutive patients under 40 years of age underwent microsurgical resection of unilateral sporadic VS via the retrosigmoid approach. The study cohort was subdivided into two groups according to the age range: group A, age range 15-30 years (n = 23 patients), and group B, age range 31-40 years (n = 27 patients). The adherence of VS capsule to surrounding nervous structures and the tendency of the tumors to bleed were evaluated by reviewing video records; the course of the FN in relation to the tumor's surface was assessed in each case. Microsurgical removal of tumor was classified as total (T), near total (residual tumor volume < 5%), subtotal (residual tumor volume 5-10%), or partial (residual tumor volume > 10%). Mean tumor size of entire cohort was 2.53 (range: 0.6-5.8) cm: 2.84 cm in group A and 2.36 cm in group B (p = NS). Facial nerve course and position within the cerebellopontine angle did not differ significantly between the two groups. At 6-month follow-up, FN functional outcome was HBI-II in 69.5% in group A, versus 96.3% in group B (p < .001). Hearing preservation was achieved in 60.0% of patients of group A and in 58.3% of group B (p = NS). Total and near-total resection was feasible in 95.6% of cases of group A and in 88.9% of group B (p = NS). Tumor capsule was tightly adherent to nervous structures in 69.6% patients of group A and in 22.2% of group B (p < .05). Significant bleeding was encountered in 56.5% of group A tumors, and in 29.6% of group B tumors (p < .01). Microsurgery of VS in patients aged 40 or less is associated with good functional results, and with high rates of total and near total tumor removal. Patients < 30 years of age have more adherent tumor capsules. Furthermore, their tumors exhibit a tendency to larger sizes, to hypervascularization, to profuse intraoperative bleeding and they present worse long-term functional FN results when compared to patients in their fourth decade of life. Our limited experience seems to suggest that a near total resection in very young VS patients with large tumors should be preferred in adherent and hypervascularized cases, in order to maximize resection and preserve function.

Tumor-Related and Patient-Related Variables Affecting Length of Hospital Stay Following Vestibular Schwannoma Microsurgery

OBJECTIVE

Review a single institution's vestibular schwannoma (VS) microsurgery experience to determine (1) correlations between demographics, comorbidities, and/or surgical approach on hospital length of stay (LOS) and discharge disposition and (2) trends in surgical approach over time.

METHODS

Retrospective case series from a multidisciplinary skull base program at a tertiary care, academic hospital. All adult (>18 years) patients undergoing primary microsurgery for VS between 2008 and 2018 were included.

RESULTS

A total of 147 subjects were identified. Surgical approach was split between middle fossa (MF) (16%), retrosigmoid (RS) (35%), and translabyrinthine (TL) (49%) craniotomies. For the 8% of patients had other than routine (OTR) discharge. Mean LOS was significantly longer for patients undergoing RS than either MF or TL. Brainstem compression by the tumor was associated with longer LOS as were diagnoses of chronic obstructive pulmonary disease (COPD) and peripheral vascular disease (PVD). For all discharges, the 40 to 50- and 50 to 60-year-old subgroups had significantly shorter LOS than the 70-years-and-older patients. For the 92% of patients routinely discharged, there was a significantly shorter LOS in the 40 to 50-year-olds compared to the 70-years-and-older patients. There was a significant shift in surgical approach from RS to TL over the study period.

CONCLUSION

Over 90% of VS microsurgery patients were routinely discharged with a median hospital LOS of 3.2 days, both of which are consistent with published data. There is an inverse relationship between age and LOS with patients older than 70 years having significantly longer LOS. Brainstem compression, COPD, PVD, and the RS approach negatively affect LOS.

LEVEL OF EVIDENCE

4.

Prevention of cerebrospinal fluid leak after vestibular schwannoma surgery: a case-series focus on mastoid air cells' partition

BACKGROUND

Petrous bone pneumatization may be related to cerebrospinal fluid (CSF) leak secondary to vestibular schwannoma surgery.

OBJECTIVE

To assess the association between petrous bone pneumatization and CSF leak in vestibular schwannoma surgery.

METHODS

A retrospective study included 222 consecutive vestibular schwannoma patients treated via a retrosigmoid or translabyrinthine approach in a 17-year period in one University Hospital. Association of CSF leak and petrous bone pneumatization, as seen on CT scans, was assessed on ANOVA and Student's t or Chi-squared test in case of non-parametric distribution.

RESULTS

One hundred and 75 resections were performed on a retrosigmoid approach and 47 on a translabyrinthine approach. Mean age was 53.6 ± 12.9 years. Mean follow-up was 5 years 6 months. Twenty-six patients (11.7%) showed CSF leak and 8 (3.6%) meningitis. Approach (p = 0.800), gender (p = 0.904), age (p = 0.234), body-mass index (p = 0.462), tumor stage (p = 0.681) and history of schwannoma surgery (p = 0.192) did not increase the risk of CSF leak. This risk was unrelated to mastoid pneumatization (p = 0.266). There was a highly significant correlation between internal acousticus meatus (IAM) posterior wall pneumatization and CSF leak after retrosigmoid surgery (p = 0.008). Eustachian tube packing in the translabyrinthine approach did not decrease risk of CSF leak (p = 0.571).

CONCLUSION

Degree of petrous bone pneumatization was not significantly related to risk of CSF leak, but pneumatization of the posterior IAM wall increased this risk in retrosigmoid surgery. Eustachian tube packing in the translabyrinthine approach is not sufficient to prevent postoperative CSF leak. Both approaches had similar rates of CSF leaks, around 12%.

Koos grade IV vestibular schwannomas: considerations on a consecutive series of 60 cases-searching for the balance between preservation of function and maximal tumor removal

Koos grade IV vestibular schwannomas (VS) (maximum diameter > 3 cm) compress the brainstem and displace the fourth ventricle. Microsurgical resection with attention to the right balance between preservation of function and maximal tumor removal is the treatment of choice. Our series consists of 60 consecutive patients with unilateral VS, operated on from December 2010 to July 2019. All patients underwent microsurgical removal via the retrosigmoid approach. The adherence of VS' capsule to the surrounding nervous structures and the excessive tendency of tumor to bleed during debulking, because of a redundant vascular architecture, was evaluated by reviewing video records. Microsurgical removal of tumor was classified as total (T), near-total (NT: residue < 5%), subtotal (ST: residue 5-10%), or partial (P: residue > 10%). Maximal mean tumor diameter was 3,97 cm (SD ± 1,13; range 3,1-5,8 cm). Preoperative severely impaired hearing or deafness (AAO-HNS classes C-D) was present in 52 cases (86,7%). Total or NT resection was accomplished in 46 cases (76,7%), 65,8% in cases with, and 95,4% without tight adhesion of capsule to nervous structures (p < 0,001). Endoscopic-assisted microsurgical removal of VS in the IAC was performed in 23 patients: in these cases, a T resection was obtained in 78,3% versus 45,9% of microsurgery only (p < 0,001). The capsule of VS was tightly adherent to nervous structures in 63,3% of patients, whereas hypervascular high-bleeding tumors represented 56,7%. Hearing preservation was possible in 2 out of 8 patients with preoperative class B hearing. At last follow-up, 34 (56,7%) patients had a normal postoperative FN outcome (HBI), 9 (15,0%) were HBII, 8 (13,3%) HBIII, and 9 (15,0%) HBIV. The total NT resection of solid and low-bleeding VS, without tight capsule adhesion, was associated with better FN outcome. Mortality was zero; permanent complications were observed in 2 cases (diplopia, hydrocephalus), transient in 9. Microsurgery of Koos grade IV VS seems to be associated with more than acceptable functional results, with high rate of T and NT removal of tumor. Long-term FN results seem to be worse in patients with cystic Koos grade IV VS, in cases with tight capsule adherences to nervous structures and in high-bleeding tumors.

A microscope-assisted endoscopic transcanal transpromontorial approach for vestibular schwannoma resection: a preliminary report

OBJECTIVE

To evaluate the feasibility of a microscope-assisted endoscopic transcanal transpromontorial approach (METTA) for the removal of small vestibular schwannomas (VS) limited to the internal auditory canal (IAC), and introduce a modification without external auditory canal (EAC) closure.

METHODS

Between August 2018 and February 2019, seven patients with intrameatal VS underwent surgery in our center, endoscopic transcanal transpromontorial approach was applied in the first 2 patients and the rest 5 patients were operated via METTA. Treatment outcomes including efficacy of tumor resection, facial nerve outcome, operation time and post-operative course were recorded and analyzed.

RESULTS

All seven patients were pathologically confirmed to have intrameatal VS. Total tumor removal was achieved in all cases. Two patients experienced cerebrospinal fluid leakage which resolved spontaneously within 5 days. The average operation time was 161.41 ± 18.42 min. All patients presented normal facial nerve function 1 month after surgery.

CONCLUSION

The METTA was effective in the removal of intrameatal VS. It can be an alternative surgical option for intrameatal VS with no serviceable hearing.

Morbidity Rate of the Retrosigmoid versus Translabyrinthine Approach for Vestibular Schwannoma Resection

Background and Objectives

Controversy related to the choice of surgical approach for vestibular schwannoma (VS) resection remains. Whether the retrosigmoid (RS) or translabyrinthine (TL) approach should be performed is a matter of debate. In the context of a lack of clear evidence favoring one approach, we conducted a retrospective study to compare the morbidity rate of both surgical approaches.

Subjects and Methods

168 patients underwent surgical treatment (2007-2013) for VS at our tertiary care center. There were no exclusion criteria. Patients were separated into two groups according to the surgical approach: TL group and RS group. Signs and symptoms including ataxia, headache, tinnitus, vertigo and cranial nerve injuries were recorded pre- and postoperatively. Surgical complications were analyzed. Perioperative facial nerve function was measured according to House-Brackmann grading system.

Results

Tumor resection was similar in both groups. Facial paresis was significantly greater in RS group patients preoperatively, in the immediate postoperative period and at one year follow-up (p<0.05). A constant difference was found between both groups at all three periods (p=0.016). The evolution of proportion was not found to be different between both groups (p=0.942), revealing a similar rate of surgically related facial paresis. Higher rate of ataxic gait (p=0.019), tinnitus (p=0.039) and cranial nerve injuries (p=0.016) was found in RS group patients. The incidence of headache, vertigo, vascular complications, cerebrospinal fluid leak and meningitis was similar in both groups. No reported mortality in this series.

Conclusions

Both approaches seem similar in terms of resection efficacy. However, according to our analysis, the TL approach is less morbid. Thus, for VS in which hearing preservation is not considered, TL approach is preferable.

Translabyrinthine microsurgical resection of small vestibular schwannomas

OBJECTIVE

Translabyrinthine resection is one of a number of treatment options available to patients with vestibular schwannomas. Though this procedure is hearing destructive, the authors have noted excellent clinical outcomes for patients with small tumors. The authors review their experience at a tertiary acoustic neuroma referral center in using the translabyrinthine approach to resect small vestibular schwannomas. All operations were performed by a surgical team consisting of a single neurosurgeon and 1 of 7 neurotologists.

METHODS

Data from a prospectively maintained clinical database were extracted and reviewed. Consecutive patients with a preoperative diagnosis of vestibular schwannoma that had less than 1 cm of extension into the cerebellopontine angle, operated on between 2008 and 2013, were included. Patents with neurofibromatosis Type 2, previous treatment, or preexisting facial weakness were excluded. In total, 107 patients were identified, 74.7% of whom had poor hearing preoperatively.

RESULTS

Pathologically, 6.5% of patients were found to have a tumor other than vestibular schwannoma. Excluding two malignancies, the tumor control rates were 98.7%, as defined by absence of radiographic disease, and 99.0%, as defined by no need for additional treatment. Facial nerve outcome was normal (House-Brackmann Grade I) in 97.2% of patients and good (House-Brackmann Grade I–II) in 99.1%. Complications were cerebrospinal fluid leak (4.7%) and sigmoid sinus thrombosis (0.9%), none of which led to long-term sequelae.

CONCLUSIONS

Translabyrinthine resection of small vestibular schwannomas provides excellent results in terms of complication avoidance, tumor control, and facial nerve outcomes. This is a hearing-destructive operation that is advocated for selected patients.

Hydroxyapatite cement cranioplasty following translabyrinthine approach: Long-term study of 369 cases

OBJECTIVE

To report the authors' experience with hydroxyapatite cement (HAC) cranioplasty and analyze the material's long-term safety and efficacy in repairing translabyrinthine skull-base defects by examining adverse events, specifically cerebrospinal fluid (CSF) leaks and surgical site infections.

STUDY DESIGN

Retrospective case-control study (primary study arm); prospective cross-sectional study of patients not examined within the last 5 years (secondary arm).

SETTING

tertiary-care neurotology private practice and academic practice (two centers).

METHODS

Hydroxyapatite cement implanted following translabyrinthine approach, with or without fat graft, was included. Combined approaches were excluded. Implant-associated adverse events were defined as 1) CSF leaks requiring reoperation or spinal drainage, and (2) infections requiring reoperation. Patients not examined within 5 years were interviewed by telephone to update their condition. Incidence of adverse events was compared to published data for translabyrinthine cranioplasty using fat graft alone. Implant survival analysis was performed.

RESULTS

The study cohort included 369 HAC implants in the same number of patients. There were seven CSF leaks and seven infections. Combined (n = 14) incidence of adverse events was 3.8% (2.09%, 6.28%). Compared to fat graft alone, the adverse events associated with HAC were fewer (P < 0.001). Up to 15 years (5,475 days), HAC cement maintained 95% adverse event-free survival. There were no cases of meningitis.

CONCLUSION

Cranioplasty using HAC with autologous fat following translabyrinthine skull-base surgery is safer and more effective than fat graft alone, up to 15 years after surgery.

LEVEL OF EVIDENCE

4. Laryngoscope, 127:2120-2125, 2017.

Surgery of the ear and the lateral skull base: pitfalls and complications

Surgery of the ear and the lateral skull base is a fascinating, yet challenging field in otorhinolaryngology. A thorough knowledge of the associated complications and pitfalls is indispensable for the surgeon, not only to provide the best possible care to his patients, but also to further improve his surgical skills. Following a summary about general aspects in pre-, intra-and postoperative care of patients with disorders of the ear/lateral skull base, this article covers the most common pitfalls and complications in stapes surgery, cochlear implantation and surgery of vestibular schwannomas and jugulotympanal paragangliomas. Based on these exemplary procedures, basic "dos and don'ts" of skull base surgery are explained, which the reader can easily transfer to other disorders. Special emphasis is laid on functional aspects, such as hearing, balance and facial nerve function. Furthermore, the topics of infection, bleeding, skull base defects, quality of life and indication for revision surgery are discussed. An open communication about complications and pitfalls in ear/lateral skull base surgery among surgeons is a prerequisite for the further advancement of this fascinating field in ENT surgery. This article is meant to be a contribution to this process.

Predictive factors influencing facial nerve outcomes in surgery for small-sized vestibular schwannoma

CONCLUSION

The most important predictive factor of facial nerve outcome in surgery for small-sized vestibular schwannoma (VS) is the adhesion between the tumor and the facial nerve.

OBJECTIVES

To compare the facial nerve outcomes between middle cranial fossa (MCF) and translabyrinthine (TL) approaches, and to analyze the preoperative and intraoperative factors influencing facial nerve outcome after small VS surgery in our neurotologic department.

METHODS

A total of 29 patients were retrospectively analyzed, with 16 in the MCF group and 13 in the TL group. Facial function was serially evaluated according to the House-Brackmann classification at 7 days, 1 month, 3 months, 6 months, and 1 year postoperatively. The effects of variables such as the surgical approach, tumor size, nerve origin, extrameatal extension, intraoperative tumor adhesion to the facial nerve, and facial nerve displacement were determined.

RESULTS

Early and late facial nerve outcomes showed no significant correlation with surgical approach, tumor origin, tumor size, extrameatal extension, or facial nerve displacement pattern. However, a significant correlation was observed with tumor adhesion to the facial nerve and facial nerve outcomes.

Fascial sling technique for dural reconstruction after translabyrinthine resection of acoustic neuroma: technical note

Reconstruction of presigmoid dural defects after resection of acoustic neuromas via the translabyrinthine approach is paramount to prevent postoperative CSF leakage. However, primary dural reapproximation and achieving a watertight closure of the dural defect in this anatomical region are quite difficult. Standard closure techniques after the translabyrinthine approach often involve packing an abdominal fat graft that plugs the dural defect and mastoidectomy cavity. This technique, however, may pose the risk of direct compression of the fat graft on the facial nerve and brainstem. Nonetheless, even with the evolution in dural repair techniques, postoperative CSF leaks can still occur and provide a route for infection and meningitis. In this report, the authors describe a novel dural “sling” reconstruction technique using autologous fascia lata to repair presigmoid dural defects created after translabyrinthine resection of acoustic neuromas. The fascia lata is sewn to the edges of the presigmoid dural defect to create a sling to suspend the fat graft within the mastoidectomy defect. A titanium mesh plate embedded in porous polyethylene is secured over the mastoidectomy defect to apply pressure to the fat graft. In the authors' experience, this has been a successful technique for dural reconstruction after translabyrinthine removal of acoustic neuromas to prevent postoperative CSF leakage. There were no cases of CSF leakage in the first 8 patients treated using this technique. The operative details and preliminary results of this technique are presented.

What really decides the facial function of vestibular schwannoma surgery?

Objectives

To find the main cause of facial nerve dysfunction in vestibular schwannoma (VS) surgery and review the prognosis of facial function in relation to tumor size, preoperative facial function and surgical approach.

Methods

We reviewed the surgical outcome of 134 patients with VS treated in our department between 1994 and 2008. All patients included in the study had postoperative facial paralysis after surgical management of their VS. There were 14 women and 7 men. The mean age was 48.5 years, with a mean follow-up period of 57 months.

Results

Twenty-one patients (sustained facial palsy, 4; newly developed facial palsy, 17) had facial nerve paralysis after surgery: ten patients in large VS and eleven patients in small VS. In large VS group, 4 patients had facial nerve function of HB grade II, 3 patients had HB grade III, and 3 patients had HB grade IV. In small VS group, 9 patients had HB grade II and 2 patients had HB grade IV. Middle cranial fossa approach rather than translabyrinthine approach for the preservation of hearing, led to facial nerve deterioration and the patients who had facial nerve paralysis perioperatively, had resulted in permanent facial paralysis.

Conclusion

The tumor size in VS is certainly one of the most important prognostic factors. However, VS tumor size alone should not be considered a unique prognostic indicator. The surgical approach used, which may be related to tumor size, based on the surgeon's experience, can be a deciding factor, and the status of the facial nerve injured by the tumor can influence postoperative facial nerve function.

Microsurgical excisions of vestibular schwannomas: A tumor-size-based analysis of neurological outcomes and surgical complications

INTRODUCTION

Vestibular schwannomas (VS) are benign tumors originating from Schwann cells in vestibulocochlear nerve. This study aimed at evaluating outcomes of microsurgical resections of VS based on tumor sizes in a South Asian country.

METHODS

The chart notes of 71 patients who underwent microsurgical resections of VS at a single academic center over a 20-year period (1990-2009) were reviewed, and relevant information was extracted. For analyzing outcomes, patients were divided into two groups based on tumor size at initial presentation: (1) Group A (tumor size ≤ 4 cm) and (2) Group B (tumor size > 4 cm). Pearson's chi-square and Fisher's exact tests were used for comparison of proportions; the independent sample t-test was used for comparison of means.

RESULTS

The average tumor diameter was 4.1 ± 1.5 (range, 1-6.6) cm. Complete resection was achieved more frequently in patients in Group A (P < 0.001). Duration of hospital stay and cost of treatment were significantly higher in Group B patients (P < 0.003 and P < 0.04, respectively). The severity of postoperative facial nerve injury, assessed by House-Brackmann grading system, was significantly higher in Group B (P < 0.01). Cerebrospinal fluid (CSF) leak and lower cranial nerve deficits also occurred more frequently after resection in Group B (P = 0.031 and P = 0.003, respectively).

CONCLUSION

We conclude that advanced stage tumors suggestive of delayed presentation are fairly common in Pakistan, and limit curative resection in the majority of patients. Postoperative morbidity is significantly higher in patients with tumor size > 4 cm.

Perioperative complications after translabyrinthine removal of large or giant vestibular schwannoma: Outcomes for 123 patients

CONCLUSION

Large vestibular schwannomas are benign but dangerous tumors. The translabyrinthine approach allows the surgeon to limit vital and functional complications due to the disease itself or to its surgical removal.

OBJECTIVE

Morbi-mortality study focused on large vestibular schwannoma surgically treated by translabyrinthine removal.

METHODS

This was a retrospective review of prospectively collected data in a series of 123 patients who underwent translabyrinthine removal of a large vestibular schwannoma (>4 cm in the cerebellopontine angle, stage IV). All surgical and medical complications and facial function were reviewed, with a 1-year follow-up.

RESULTS

Mortality during the first year was 0.8% (one case of infarct of the anterior inferior cerebellar artery, fatal after 8 months). In all, 4.9% of patients underwent a second surgery (for delayed hemorrhage or cerebrospinal fluid leak) during the first months after removal of a large vestibular schwannoma; 3.2% of patients experienced definitive neurologic complications (one death, one cerebellar disturbance, and two cases of 10th cranial nerve palsy).

Functional outcome after complete surgical removal of giant vestibular schwannomas

OBJECT

The authors evaluated the outcome of radical surgery in a consecutive series of patients with giant vestibular schwannomas (VSs).

METHODS

Fifty patients with VSs > 4.0 cm in maximal extrameatal diameter were included in this retrospective study (Group A). The group was compared with a matched group of 167 patients with VSs < 3.9 cm (Group B). In all cases the retrosigmoid approach was used. Outcome measures included completeness of tumor removal, facial nerve function, hearing, and the surgery-related complication rate.

RESULTS

The mean tumor size in Group A was 4.4 cm and that in Group B was 2.3 cm. Total removal was achieved in all Group A patients and in 97.6% of Group B patients. The anatomical integrity of the facial nerve was preserved in 92% in Group A and in 98.8% in Group B. At last follow-up 75% of the patients with giant VSs had excellent or good facial nerve function, 19% had fair function, and 6% had poor function. In 33% of patients (3 cases) with good preoperative hearing level, it was preserved. Newly developed lower cranial nerve dysfunction occurred in 3 patients but proved to be temporary in 2 of them. A CSF leak developed in 6% of those who not previously undergone surgery. Compared with Group B, a significant difference was found only in the rates of the following parameters: excellent facial nerve function, useful and good hearing, lower cranial nerve dysfunction, and blood collection (p < 0.05). The perioperative mortality rate in both groups was 0%.

CONCLUSIONS

In patients with a giant VS, total tumor removal can be achieved via the retrosigmoid approach with a 0% mortality rate and low morbidity rate, especially with regards to facial nerve function. In selected cases even hearing preservation is possible. Tumor size significantly correlates with postoperative outcome.

Do facial nerve displacement pattern and tumor adhesion influence the facial nerve outcome in vestibular schwannoma surgery?

OBJECTIVE

To assess the nerve facial displacement by a vestibular schwannoma and nerve adhesion to tumor as predictive factors of facial function outcome.

STUDY DESIGN

A prospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Ninety-six patients undergoing a solitary vestibular schwannoma surgery during 2005 were included. Data concerning tumor size (Stage 1, intracanalicular; Stage 2, < or =15 mm in the cerebellopontine angle [CPA]; Stage 3, 15-30 mm in the CPA; and Stage 4, >30 mm in the CPA), intraoperative facial nerve displacement (Type 1, anterior to the tumor; Type 2, anterior and superior to the tumor and separated from the cochlear nerve; Type 3, superior to the tumor; and Type 4, posterior to the tumor), degree of tumor adhesion (weak, intermediate, and strong) and postoperative facial function according to the House and Brackmann classification at days 10, 30, 90 and 180 were collected.

RESULTS

A good facial function (Grade 1 or 2) was reported in 73% at postoperative Day 180. Univariate analysis showed that facial outcome was better in small tumors, in displacement Types 1 and 2 (Type 1, 46%; Type 2, 34%; and Type 3, 20%), and in tumors with weak and intermediate adhesion (weak, 10%; intermediate, 38%; and strong, 52%). Facial nerve displacement and adhesion were related to tumor stage. The combination of tumor stage, adhesion, and nerve displacement in a logistic regression model was highly predictive of postoperative facial function.

CONCLUSION

Facial nerve displacement and nerve adhesion to tumor are significant predictive factors of facial function outcome after vestibular schwannoma surgery in addition to tumor size.

Vascular complications of vestibular schwannoma surgery: a comparison of the suboccipital retrosigmoid and translabyrinthine approaches

Object

Vascular complications of the surgery for vestibular schwannomas (VSs) can have devastating consequences; however, there is scant literature on the systematic analysis of the different types of complications. In this context, the authors of this study analyzed these complications, with particular interest in the role of surgical approach in their occurrence.

Methods

The charts of 391 patients who had undergone 413 procedures for VS during a 24-year period were reviewed retrospectively. A suboccipital retrosigmoid (RS) approach was used in 338 procedures, and the translabyrinthine (TL) route in 75. Postoperative hemorrhage or infarction was identified and stratified according to the complication type and surgical approach.

Postoperative vascular complications were encountered in 11 procedures (2.7%), and their incidence was the same for both the RS and TL approaches. Of these complications, eight were hemorrhagic (two cerebellopontine angle, one intracerebellar, and five epidural hematomas) and three were ischemic in nature. Five patients (45.4%) had a complete recovery, and four patients (36.4%) a partial recovery; two patients (18.2%) died. The overall procedure-related mortality rate was 0.5% (two of 413 procedures): 0.3% (one of 338 procedures) for the RS approach and 1.3% (one of 75 procedures) for the TL approach (p > 0.05).

Conclusions

In this study, the overall incidences of vascular complications in VS surgery were similar for the RS and TL approaches. Regardless of the preferred surgical route, this group of complications carries a significant risk of morbidity and therefore warrants special consideration in the management of VSs.

Facial nerve function after excision of large acoustic neuromas via the suboccipital retrosigmoid approach

We review our results for facial nerve preservation in 105 patients with large acoustic neuromas (diameter 4.0 cm or larger) undergoing excision via the suboccipital retrosigmoid approach. Microneurosurgical techniques and facial nerve monitoring were used. Complete tumor removal was achieved in 91 cases (86.7%) and subtotal removal in 14 (13.3%). There were two postoperative deaths (1.9%). The facial nerve was preserved anatomically in 83 (79.1%) patients. Using the House-Brackmann grading system, facial nerve function was assessed immediately after surgery, at the time of discharge and 1 year after surgery. Excellent function (Grades I and II) was present in 41.0%, 41.8%, and 56.7% of patients at each time interval, respectively, with acceptable function (Grade I-IV) in 78.5% (68/87 cases) at follow-up assessment at one year. The suboccipital retrosigmoid approach resulted in good anatomical and functional preservation of the facial nerve during excision of large acoustic neuromas, with minimal other morbidity and low mortality. We recommend this approach for excision of large acoustic neuromas.

Cranial nerve preservation in surgery for large acoustic neuromas

Facial nerve outcomes and surgical complication rates for other cranial nerves were evaluated retrospectively after the resection of large acoustic neuromas. The charts of all patients who underwent surgical removal of an acoustic neuroma between 1992 and 2001 at New York University Medical Center were reviewed. Fifty-four patients with tumors measuring 3 cm or larger were included in the study. Four patients had neurofibromatosis type 2, two of whom underwent bilateral removal of acoustic neuromas. Translabyrinthine microsurgical removal of tumor was performed in 47 of 56 cases (84%). In all cases, EMG monitoring, improved sharp microdissection, and ultrasonic aspiration were employed. Facial nerve function was assessed using the House-Brackmann facial nerve grading system immediately after surgery and at follow-up visits. A House-Brackmann grade III or better was achieved in 90% of patients, and a grade II or better was achieved in 84% of patients. Ultimate facial nerve outcome was excellent after the surgical resection of large acoustic neuromas. Preoperative cranial nerve palsies also improved after surgery. The translabyrinthine approach for tumor removal is our treatment of choice for acoustic neuromas 3 cm or larger.

Resection of large vestibular schwannomas: facial nerve preservation in the context of surgical approach and patient-assessed outcome

Object. Vestibular schwannoma surgery has evolved as new therapeutic options have emerged, patients' expectations have risen, and the psychological effect of facial nerve paralysis has been studied. For large vestibular schwannomas for which extirpation is the primary therapy, the goals remain complete tumor resection and maintenance of normal neurological function. Improved microsurgical techniques and intraoperative facial nerve monitoring have decreased the complication rate and increased the likelihood of normal to near-normal postoperative facial function. Nevertheless, the impairment most frequently reported by patients as an adverse effect of surgery continues to be facial nerve paralysis. In addition, patient assessment has provided a different, less optimistic view of outcome. The authors evaluated the extent of facial function, timing of facial nerve recovery, patients' perceptions of this recovery and function, and the prognostic value of intraoperative facial nerve monitoring following resection of large vestibular schwannomas; they then analyzed these results with respect to different surgical approaches.

Methods. The authors retrospectively reviewed a database of 67 patients with 71 vestibular schwannomas measuring 3 cm or larger in diameter. The patients had undergone surgery via translabyrinthine, retrosigmoid, or combined approaches. Clinical outcomes were analyzed with respect to intraoperative facial nerve activity, responses to intraoperative stimulation, and time course of recovery.

Eighty percent of patients obtained normal to near-normal facial function (House—Brackmann Grades I and II). Patients' perceptions of facial nerve function and recovery correlated well with the clinical observations.

Conclusions. Trends in the data lead the authors to suggest that a retrosigmoid exposure, alone or in combination with a translabyrinthine approach, offers the best chance of facial nerve preservation in patients with large vestibular schwannomas.

Management Options for Cerebrospinal Fluid Leak after Vestibular Schwannoma Surgery and Introduction of an Innovative Treatment

OBJECTIVE

To review the management of cerebrospinal fluid leak after vestibular schwannoma removal reported in the literature and to present a novel approach to management of recalcitrant cases.

DATA SOURCES

MEDLINE and PubMed literature search using the terms "cerebrospinal fluid leak" or "cerebrospinal fluid fistula" and "acoustic neuroma" or "vestibular schwannoma" covering the period from 1985 to present in English. A review of bibliographies of these studies was also performed.

STUDY SELECTION

Criteria for inclusion in this meta-analysis consisted of the availability of extractable data from studies presenting a defined group of patients who had undergone primary vestibular schwannoma removal and for whom the presence and absence of cerebrospinal fluid leakage was reported. Studies reporting combined approaches were excluded. No duplications of patient populations were included. Twenty-five studies met the inclusion criteria.

DATA EXTRACTION

Quality of the studies was determined by the design of each study and the ability to combine the data with the results of other studies. All of the studies were biased by their retrospective, nonrandomized nature.

DATA SYNTHESIS

Significance (p < 0.05) was determined using the chi test.

CONCLUSIONS

Incisional cerebrospinal fluid leakage responded well to local management and lumbar drainage. Rhinorrhea often necessitated surgical intervention. No specific reoperation techniques correlated exclusively with better reoperation outcomes. The transaural/transnasal approach presents an alternative for surgical management of cerebrospinal fluid rhinorrhea.

Cerebrospinal Fluid Leak Prevention After Translabyrinthine Removal of Vestibular Schwannoma

OBJECTIVES/HYPOTHESIS

The purpose of the report was to present an update on the authors' results for prevention and management of cerebrospinal fluid (CSF) leak after translabyrinthine approach for vestibular schwannoma.

STUDY DESIGN

: Retrospective case review.

METHODS

The study was conducted at Gruppo Otologico (Piacenza, Italy), a tertiary referral center for neurotology and skull base surgery. In all, 710 patients underwent translabyrinthine approach for the removal of vestibular schwannoma at that institution between April 1987 and December 2002. The medical records were retrospectively reviewed to identify tumor size, the incidence of postoperative CSF leak, and its treatment.

RESULTS

The overall rate of CSF leak was 1.4%.

CONCLUSION

The use of proper surgical technique minimizes the risk of CSF leak. Study results show that the continued application of the authors' proposed preventive measures resulted in the maintenance of a low rate of CSF leak. Immediate management of CSF fistulae helps prevent meningitis.

Quality of Life in patients with vestibular schwannomas managed conservatively

Since the era of magnetic resonance imaging (MRI) scanning, vestibular schwannomas are being diagnosed earlier, growth has been shown to be static in up to 70% of cases and patients have admitted to a reduced quality of life following acoustic neuroma surgery. The aim of this study was to assess the quality of life in patients with vestibular schwannomas managed conservatively. Fifty patients with a vestibular schwannoma were identified who were being managed by interval MRI scanning. Fifty patients attending the general otolaryngology clinic with similar symptoms were prospectively recruited. Each group was assessed using the short form 36 (SF-36) health survey. Both groups were adequately age and sex matched and the SF-36 scores were comparable across all eight health domains.

The Incidence of Cerebrospinal Fluid Leak after Vestibular Schwannoma Surgery

OBJECTIVE

To review the incidence of cerebrospinal fluid leak after vestibular schwannoma removal reported in the literature.

DATA SOURCES

MEDLINE and PubMed literature search using the terms "acoustic neuroma" or "vestibular schwannoma," and "cerebrospinal fluid leak" or "cerebrospinal fluid fistula" covering the period from 1985 to the present in the English language literature. A review of bibliographies of these studies was also performed.

STUDY SELECTION

Criteria for inclusion in this meta-analysis consisted of the availability of extractable data from studies presenting a defined group of patients who had undergone primary vestibular schwannoma removal and for whom the presence and absence of cerebrospinal fluid leakage was reported. Studies reporting combined approaches were excluded. No duplications of patient populations were included. Twenty-five studies met the inclusion criteria.

DATA EXTRACTION

Quality of the studies was determined by the design of each study and the ability to combine the data with the results of other studies. All of the studies were biased by their retrospective, nonrandomized nature.

DATA SYNTHESIS

Significance (p < 0.05) was determined using the chi2 test.

CONCLUSIONS

Cerebrospinal fluid leak occurred in 10.6% of 2,273 retrosigmoid surgeries, 9.5% of 3,118 translabyrinthine surgeries, and 10.6% of 573 middle fossa surgeries. The type of cerebrospinal fluid leak was not associated with surgical approach. Meningitis was significantly associated with cerebrospinal fluid leak (p < 0.05). Age and tumor size were not associated with cerebrospinal fluid leak.

One-stage Removal of Residual Intracanalicular Acoustic Neuroma and Hemihypoglossal-intratemporal Facial Nerve Anastomosis: Technical Note

OBJECTIVE AND IMPORTANCE

Incomplete removal of residual intracanalicular tumor and injury to the facial nerve are the main problems associated with surgery of large acoustic neuromas via the retromastoid suboccipital approach. In patients with residual or recurrent intracanalicular neuromas, the translabyrinthine approach is the preferred surgical route, allowing complete tumor removal; it may eventually also be used for exposure of the intratemporal portion of the facial nerve for a hemihypoglossal-facial nerve anastomosis when a postoperative facial palsy exists This one-stage procedure has not been described previously.

CLINICAL PRESENTATION

Three patients with postoperative facial palsy and residual intracanalicular tumor after surgical removal of a large acoustic neuroma via the retromastoid suboccipital approach underwent reoperation via the translabyrinthine approach and one-stage removal of the residual tumor and hemihypoglossal-facial nerve anastomosis. All three patients had a complete facial palsy of House-Brackmann Grade VI and a residual tumor of 8 to 12 mm.

TECHNIQUE

A classic translabyrinthine approach was used to open the internal auditory canal and remove the residual intracanalicular tumor. The facial nerve was exposed in its mastoid and tympanic parts, mobilized, and transected; then, the long nerve stump was transposed into the neck and used for an end-to-side anastomosis into the hypoglossal nerve. The operation resulted in variable improvement of the facial muscle function up to Grade III (one patient) and Grade IV (two patients).

CONCLUSION

Reoperation via the translabyrinthine approach is indicated for removal of residual intracanalicular acoustic neuroma and realization of a hypoglossal-facial nerve anastomosis in a single procedure. It is suggested that this type of anastomosis may also be used during the initial operation for acoustic neuroma removal when the facial nerve is inadvertently sectioned.

Cerebrospinal fluid leak after acoustic neuroma surgery: a comparison of the translabyrinthine, middle fossa, and retrosigmoid approaches

OBJECTIVE

To determine whether the choice of surgical approach affects the rate of postoperative cerebrospinal fluid leakage in patients who have undergone surgical resection of acoustic neuroma.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

Three hundred patients who underwent surgery for acoustic neuromas were selected by consecutive medical record number until 100 resections via each surgical approach (translabyrinthine, middle fossa, and retrosigmoid) had been gathered.

MAIN OUTCOME MEASURES

Surgical approach used, cerebrospinal fluid leak incidence, tumor size, patient age.

RESULTS

Postoperative cerebrospinal fluid leak of any severity was observed in 13% of translabyrinthine, 10% of middle fossa, and 10% of retrosigmoid patients. These difference in the rate of cerebrospinal fluid leakage were not statistically significant (p = 0.82). The majority of leaks were managed conservatively with fluid and activity restriction, often accompanied by a period of lumbar subarachnoid drainage. There was a need to return to the operating room for a definitive procedure in 4% of translabyrinthine, 2% of middle fossa, and 3% retrosigmoid patients; again not statistically different among the approaches (p = 0.43). Tumor size was not correlated with cerebrospinal fluid leak rate (p = 0.13). Patient age, for patients older than 50 years, was suggestive of increased odds of cerebrospinal fluid leak (p = 0.06).

CONCLUSION

Neither surgical approach nor tumor size affects the rate of postoperative cerebrospinal fluid leakage or the necessity of managing a leak with a return to the operating room. Cerebrospinal fluid leakage rates have remained stable in recent decades despite numerous innovative attempts to improve dural closure, seal transected air cell tracts, and occlude anatomic pathways. The finding that leak rates were similar among three dissimilar surgical techniques suggests that factors other than techniques of wound closure, such as transient postoperative rises in cerebrospinal fluid pressure, may be responsible for these recalcitrant cases.

Cerebrospinal fluid leak after acoustic neuroma surgery: influence of tumor size and surgical approach on incidence and response to treatment

OBJECT

The aims of this study were to review the incidence of cerebrospinal fluid (CSF) leakage complicating the removal of acoustic neuroma and to identify factors that influence its occurrence and treatment.

METHODS

Prospective information on consecutive patients who underwent operation for acoustic neuroma was supplemented by a retrospective review of the medical records in which patients with CSF leaks complicating tumor removal were identified. This paper represents a continuation of a previously published series and thus compiles the authors' continuous experience over the last 24 years of practice. In 624 cases of acoustic neuroma the authors observed an overall incidence of 10.7% for CSF leak. The rate of leakage was significantly lower in the last 9 years compared with the first 15, most likely because of the abandonment of the combined translabyrinthine (TL)-middle fossa exposure. There was no difference in the leakage rate between TL and retrosigmoid (RS) approaches, although there were differences in the site of the leak (wound leaks occurred more frequently after a TL and otorrhea after an RS approach, respectively). Tumor size (maximum extracanalicular diameter) had a significant effect on the leakage rate overall and for RS but not for TL procedures. The majority of leaks ceased with nonsurgical treatments (18% with expectant management and 49% with lumbar CSF drainage). However, TL leaks (especially rhinorrhea) required surgical repair significantly more often than RS leaks. This has not been reported previously.

CONCLUSIONS

The rate of CSF leakage after TL and RS procedures has remained stable. Factors influencing its occurrence include tumor size but not surgical approach. The TL-related leaks had a significantly higher surgical repair rate than RS-related leaks, an additional factor to consider when choosing an approach. The problem of CSF leakage becomes increasingly important as nonsurgical treatments for acoustic neuroma are developed.

A review of facial nerve outcome in 100 consecutive cases of acoustic tumor surgery

OBJECTIVE

To determine the facial nerve outcomes at a tertiary neurotological referral center specializing in acoustic neuroma and skull base surgery.

STUDY DESIGN

Retrospective review of 100 consecutive patients in whom acoustic neuromas were removed using all of the standard surgical approaches.

METHODS

Functional facial nerve outcomes were independently assessed using the House-Brackmann facial nerve grading system.

RESULTS

The tumors were categorized as small, medium, large, and giant. If one excludes the three patients with preoperative facial palsies, 100% of the small tumors, 98.6% of the medium tumors, 100% of the large tumors, and 71% of the giant tumors had facial nerve function grade I-II/VI after surgery.

CONCLUSION

Facial nerve results from alternative nonsurgical treatments must be compared with facial nerve outcomes from experienced surgical centers. Based on the facial nerve outcomes from our 100 consecutive patients, microsurgical resection remains the preferred treatment modality for acoustic tumors.

Current surgical results of retrosigmoid approach in extralarge vestibular schwannomas

BACKGROUND

Vestibular schwannomas (VS) are common tumors that can be cured; they are reported to comprise 6 approximately 8% of all intracranial tumors. The primary objective in the surgery of extralarge VS is total removal of the tumor mass while preserving the facial nerve. In extralarge tumors, complete excision of the tumor carries a significant risk of injuring the facial nerve and adjacent vital brain structures. The authors are reporting the techniques and results of operation on extralarge VS.

METHODS

The material consisted of 30 patients during the last 6 years with surgically treated VS that had a maximal extrameatal diameter exceeding 4 cm. Suboccipital craniotomy and tumor removal was performed with patients in the lateral position. Results and complications of the surgical technique will be reviewed.

RESULTS

Average age of patients was 45.2 years; there was a slight female predominance (1.5:1). Size of the mass ranged from 41 to 70 mm; all were removed by the retrosigmoid transmeatal approach. Peritumoral edema on MRI was seen in 50% (15/30). Total removal was achieved in 73.3% (22/30) with no significant relationship to peritumoral edema. In the cases of total removal, the facial nerve preservation rate was 86.4% (19/22). There was no mortality. Surgical complications were hemorrhage and CSF leakage in 1 case (3%) and 8 cases (26.7%), respectively, but in most of these cases, conservative treatment was adequate. In patients in whom anatomic preservation of the facial nerve was achieved, facial nerve function improved progressively within a year. In all cases except for one with gait disturbance, a good outcome was achieved.

CONCLUSIONS

Our surgical techniques, including the prediction of facial nerve displacement, not using retractors, and replacement of bone, contributed to good surgical results in a series of extralarge VS.

Postoperative quality of life in vestibular schwannoma patients measured by the SF36 Health Questionnaire

OBJECTIVE

To quantify the postoperative quality of life in patients following surgical treatment for vestibular schwannoma.

STUDY DESIGN

Patient self-assessment using the short form 36 (SF36) multidimensional quality of life health questionnaire. Sex- and age-matched normalized scores were calculated using a standardized process and accepted normative data.

SETTING

Tertiary referral skull base unit.

RESULTS

An 80% response rate (90 patients) was achieved. The postoperative quality of life in vestibular schwannoma patients, as quantified by seven of the eight SF36 health scales was less than the appropriate matched healthy standard. Comparison of a variety of preoperative patients and tumor factors-different operative approaches (translabyrinthine and retrosigmoid), tumor size (group cut of points of tumor diameter 1.5 mm and 2.5 mm), patient sex, and ranking of patient age-showed no statistically significant difference in measured quality of life outcomes for each of these traditional predictors.

CONCLUSION

Reduced quality of life in patients after surgical treatment for vestibular schwannoma, coupled with the low tumor growth rates and minimal preoperative symptoms, supports a conservative approach to patient management. The advantages and disadvantages of a variety of approaches used to measure the quality of life after surgical treatment of vestibular schwannoma and their impact on clinical decision making for patients, are discussed.

Report of 190 consecutive cases of large acoustic tumors (vestibular schwannoma) removed via the translabyrinthine approach

OBJECT

The choice of approach for surgical removal of large acoustic neuromas is still controversial. The authors reviewed the results in a series of patients who underwent removal of large tumors via the translabyrinthine approach.

METHODS

The authors conducted a database analysis of 190 patients (89 men and 101 women) with acoustic neuromas 3 cm or greater in size. The mean age of these patients was 46.1+/-15.6 years. One hundred seventy-eight patients underwent primary translabyrinthine surgical removal and 12 underwent surgery for residual tumor. Total tumor removal was accomplished in 183 cases (96.3%). The tumor was adherent to the facial nerve to some degree in 64% of the cases, but the facial nerve was preserved anatomically in 178 (93.7%) of the patients. Divided nerves were repaired by primary attachment or cable graft. Facial nerve function was assessed immediately after surgery, at the time of discharge, and at 3 to 4 weeks and 1 year after discharge. Excellent function (House-Brackmann facial nerve Grade I or II) was present in 55%, 33.9%, 38.8%, and 52.6% of the patients for each time interval, respectively, with acceptable function (Grades I-IV) in 81% at 1 year. Cerebrospinal fluid leakage that required surgical repair occurred in only 1.1% of the patients and meningitis in 3.7%. There were no deaths.

CONCLUSIONS

Use of the translabyrinthine approach for removal of large tumors resulted in good anatomical and functional preservation of the facial nerve, with minimum incidence of morbidity and no incidence of mortality. The authors continue to recommend use of this approach for acoustic tumors larger than 3 cm and for smaller tumors when hearing preservation is not an issue.

Unilateral acoustic tumors: how often do they recur after translabyrinthine removal?

Unilateral acoustic tumors rarely recur after total translabyrinthine removal. Review of the patient records of the House Ear Clinic revealed five recurrent tumors, for an approximate incidence of 0.3%. A questionnaire was mailed to 857 patients who were at least 9 years postoperative and failed to find any additional recurrent tumors. No preoperative or intraoperative factors were identified to predict recurrence. The average time interval from initial removal to recurrence was approximately 10 years. Flow cytometric analysis did not reveal any fundamental differences between the recurrent acoustic tumor group and a larger group of 112 acoustic tumors. Based on observed growth rates of the recurrent acoustic tumors, a single gadolinium-enhanced magnetic resonance image 5 years after surgery is advised. To prevent recurrence, a margin of normal-appearing proximal eighth cranial nerve should be removed and the nerve stump cauterized.

False-Positive Magnetic Resonance Imaging of Small Internal Auditory Canal Tumors: A Clinical Radiologic, and Pathologic Correlation Study

Magnetic resonance imaging with gadolinium facilitates the early diagnosis of internal auditory canal tumors at a small enough stage to permit increasing application of hearing preservation surgical techniques. Surgeons report successful removal of tumors as small as 3 mm, which are diagnosed with enhanced magnetic resonance imaging. A retrospective study was performed to determine the risk of false-positive “tumor” diagnosis with enhanced magnetic resonance imaging. We reviewed the imaging records, office notes, and surgical records of 112 consecutive “tumors” involving the internal auditory canal treated by the Wilford Hall USAF Medical Center Neurotology Service between July 1991 and July 1994. Two categories of false-positive magnetic resonance imaging were Identified: (1) surgically confirmed absence of internal auditory canal neoplasm and (2) spontaneous resolution of the internal auditory canal lesions on subsequent, enhanced magnetic resonance images. Overall, eight false-positive scans were identified. Three were surgically confirmed as false-positive, and five resolved on subsequent Imaging studies. All cases were smaller than 6 mm and involved the distal internal auditory canal (fundus). The surgically confirmed cases were approached through a middle fossa technique with successful hearing preservation. The overall rate of surgical false-positive results was 3.5% (3 cases in 86 surgeries). However, the overall false-positive rate for intracanalicular “tumors” was 32% (8 cases in 25 intracanalicular lesions). Although hearing preservation is more likely in small lesions, the surgeon must consider the possibility that an internal auditory canal lesion smaller than 6 mm may actually represent a nonneoplastic process. Enhancing lesions limited to the internal auditory canal fundus may be treated by reimaging the patient in 6 months after the first image rather than by prompt surgical exploration.

Translabyrinthine removal of large acoustic neuromas

Several surgical approaches to the cerebellopontine angle and internal auditory canal have been developed for the removal of acoustic neuromas. The choice of an approach may be influenced by hearing levels and tumor size. We reviewed the records of the primary translabyrinthine removal of 167 large (> or = 4 cm) acoustic neuromas performed between 1982 and 1990. Patients ranged in age from 15 to 83 years, with a mean of 43 years (male, 49%; female, 51%). Total removal was achieved in 95%. The facial nerve was preserved anatomically intact in 91%. At follow-up (mean, 2.1 yr), facial nerve function was acceptable (Grades I-IV) in 75% and good (Grades I-II) in 42%. Vascular complications occurred in 4.8%; however, there were no deaths. A cerebrospinal fluid leak occurred in 9.6% of cases, and meningitis occurred in 8.3%. In patients with large tumors where there is little chance to preserve preoperative hearing, we have successfully used the translabyrinthine approach for total tumor removal. The advantages and disadvantages of both the translabyrinthine and suboccipital approaches are discussed.

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.

Modified Rambo meatoplasty in translabyrinthine tumor removal

Spinal fluid otorrhea and otorhinorrhea are morbid complications that occur in up to 18% of patients after removal of translabyrinthine tumor. Both of these problems can be significantly reduced if, during the initial surgery, the posterior canal wall is taken down and the tympanic membrane and external auditory canal skin are removed for better exposure of the eustachian tube orifice. The external auditory meatus can then be sealed by a previously described modification of the Rambo procedure. This additional procedure adds about 20 minutes to the surgery and presents a small risk of retained squamous epithelium. Fifty consecutive patients were divided into two equal groups and studied retrospectively. In group I, the patients underwent a modified Rambo meatoplasty at the time of the removal of their translabyrinthine tumor, whereas patients in group II had the tympanic orifice of their eustachian tube obstructed through the facial recess. Review of the postoperative course of these fifty patients indicated that the addition of the modified Rambo meatoplasty was justified by the overall reduction in morbidity and expense it provided.

Cerebrospinal fluid leaks and meningitis in acoustic neuroma surgery

Cerebrospinal fluid leaks and associated meningitis are the most common life-threatening complications of surgery for acoustic neuromas. This retrospective study reviews 319 patients who had surgery for 321 acoustic tumors at the Sunnybrook Health Sciences Center, University of Toronto, from April 1975 to March 1990. Cerebrospinal fluid leaks occurred after 13.4% of primary tumor operations. Surgical repair was required in 6.2% of all patients; 4.4% needed more than one operation. Meningitis occurred in 5.3% of all patients. These complications were more common in larger tumors and after the combined translabyrinthine middle fossa approach. Transnasopharyngeal eustachian tube obliteration was used to stop recurrent cerebrospinal fluid leaks in two patients.

Postoperative complications in acoustic neuroma surgery by the extended middle cranial fossa approach

The complications of acoustic neuroma (AN) surgery by the extended middle cranial fossa approach were studied in 160 cases. Death during surgery occurred in 3 cases (1.9%); 2 of these involved large tumors and the third was a case of recurrence. Transient temporal lobe symptoms were seen in 24 cases (15.3%); the average tumor diameter in these cases was 36.0 mm. Beside symptoms of 7th and 8th nerve disturbance, hemiparesis was seen 7.6%; 3rd, 4th, and 6th cranial nerve symptoms in 7.0%; and cerebellar symptoms in 7.6% of the patients. The incidence of these disturbances increased with tumor size. Cerebrospinal fluid (CSF) leakage occurred in 20.4% of the cases and this necessitated surgical treatment in 5% of the cases.

Hearing conservation in acoustic neuroma surgery via the posterior fossa

An increasing number of patients with an acoustic neuroma present with useful hearing in the tumour ear. Surgical removal of these tumours via the posterior fossa route may enable preservation of the cochlear nerve and otic capsule without increasing the morbidity to the facial nerve. The results of treating 51 cases of acoustic neuroma via the posterior fossa is presented. Forty four tumours measured less than 20 mm in diameter in the cerebellopontine angle and surgery was undertaken with hearing preservation as a principle objective. In 26 cases, the cochlear nerve was preserved anatomically and post-operative hearing at levels better than mean pure tone threshold of 50 dB or 50 per cent speech discrimination was recorded in 14 patients. The preservation of hearing represents a worthwhile surgical goal in selected patients with an acoustic neuroma without increasing the operative morbidity.

The translabyrinthine approach for the removal of large acoustic neuromas

The results and the sequelae are reported from a series of consecutive 400 translabyrinthine removals of acoustic neuromas comprising almost all such tumors in Denmark during a 12-year period from 1976 to 1988. There were two intrameatal, 137 median-sized, 112 large and 149 advanced tumors, the latter having a diameter exceeding 40 mm. The mortality rate in the overall series was 2%. The incidence of cerebrospinal fluid leak occurred in 11%, and persisted for more than 2 weeks in 4%. Facial nerve function was completely normal in 67% of the patients, while only 5% required a nerve anastomosis.

Is preservation of hearing in acoustic neuroma worthwhile?

In a series of 300 translabyrinthine removals of acoustic neuromas, comprising almost all tumours operated on in Denmark during a period of 10 years, the preoperative hearing in the tumour ear and in the contralateral ear was analysed in 72 patients with tumours smaller than 2 cm in extrameatal diameter. These patients constitute likely candidates for a hearing preserving operation via the suboccipital approach. In the tumour ear in 4 patients there was a pure-tone average (PTA) of 0-20 dB and a discrimination score (DS) of 81-100%. Applying this criterion to the whole series, 1% of the patients would be candidates for a hearing preserving procedure. Changing the criterion to a PTA of 0-40 dB and a DS of 61-100%, the number of candidates would increase to 8 patients (3%), and with a PTA of 0-50 dB and a DS of 51-100% 14 candidates (5%) would have been found. In all of these patients, contralateral hearing was normal (SRT 0-20 dB, DS 95-100%). Since preservation of hearing would be achieved in only half of those subjected to suboccipital removal and since the hearing retained in patients with successful operations is generally poorer than the preoperative level, the number of patients obtaining serviceable hearing is so modest that preservation of hearing cannot be considered an argument in favour of suboccipital tumour removal. It should be borne in mind that contralateral hearing is normal in these patients and that, according to most reports, the mortality rate is higher and paralysis of the facial nerve more frequent with the suboccipital approach than with the translabyrinthine procedure.