The widened retrolabyrinthe approach: a new concept in acoustic neuroma surgery

Recent advances in Otology: Current landscape and future direction

Hearing is an essential sensation, and its deterioration leads to a significant decrease in the quality of life. Thus, great efforts have been made by otologists to preserve and recover hearing. Our knowledge regarding the field of otology has progressed with advances in technology, and otologists have sought to develop novel approaches in the field of otologic surgery to achieve higher hearing recovery or preservation rates. This requires knowledge regarding the anatomy of the temporal bone and the physiology of hearing. Basic research in the field of otology has progressed with advances in molecular biology and genetics. This review summarizes the current views and recent advances in the field of otology and otologic surgery, especially from the viewpoint of young Japanese clinician-scientists, and presents the perspectives and future directions for several topics in the field of otology. This review will aid next-generation researchers in understanding the recent advances and future challenges in the field of otology.

Brazilian Society of Otology task force - Vestibular Schwannoma ‒ evaluation and treatment

OBJECTIVE

To review the literature on the diagnosis and treatment of vestibular schwannoma.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on vestibular schwannoma were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 parts: (1) Diagnosis - audiologic, electrophysiologic tests, and imaging; (2) Treatment - wait and scan protocols, surgery, radiosurgery/radiotherapy, and systemic therapy.

CONCLUSIONS

Decision making in VS treatment has become more challenging. MRI can diagnose increasingly smaller tumors, which has disastrous consequences for the patients and their families. It is important to develop an individualized approach for each case, which highly depends on the experience of each surgical team.

Clinical correlation research of 3D reconstruction of retrolabyrinthine space based on HRCT of temporal bone

Background: The retrolabyrinthine approach helps clinicians perform complex surgeries such as vestibular neurectomy, resection of petrous apex cholesteatoma, or use this space to complete endoscopic combined with microscope surgical operations in a relatively safe buffer space. Some of our current studies using 3D reconstruction in the clinic have also helped us perform some complex surgical procedures.Objective: This study aims to reveal the relationship between important structures in retrolabyrinthine space through objective parameters. These measurement data help clinicians locate intraoperatively and provide a reference for clinical surgery. Also, we are intended to help improve surgical techniques and expand the operating space to increase reachable anatomic structure.Material and Methods: The inner structures of the temporal bone from HRCT (High-resolution computed tomography) images which were taken at the Eye & ENT Hospital of Fudan University were reconstructed. Precise measurement of the structures was accomplished by using the software 3D-Slicer (3D Slicer, https://www.slicer.org/; version 4.8.0, Massachusetts, USA).Results: 3D model of temporal bone structures, including the cochlea, semicircular canals (SCCs), the internal auditory canal (IAC), facial nerve (FN), jugular bulb(JB), and carotid artery was reconstructed. The combination of HRCT and 3D models is utilized to analyze the Quantitative data of the retrolabyrinthine space and its adjacent structures.Conclusions and Significance: 3D reconstruction of CT images clearly displayed the detailed structures of the temporal bone. Surgical adaptability of the retrolabyrinthine approach can be assessed preoperatively by image and other methods, and anatomical parameters play an important role in the retrolabyrinthine space. Therefore, this study helps to skeleton the bone as much as possible to expand the surgical space, so that the surgeon can contact the anatomical structure more diversified to expand the surgical indications.

Vestibular Schwannoma Surgery with Endoscope-Assisted Retrolabyrinthine Approach under Modified Reinforced Continuous Intraoperative Monitoring for Hearing Preservation: Experience of 33 Cases in a Single Center

Surgery for vestibular schwannoma includes various techniques such as the middle cranial fossa, suboccipital, translabyrinthine, and retrolabyrinthine approaches. The retrolabyrinthine approach does not impair the labyrinth and allows postoperative hearing preservation. Previously, we reported an endoscope-assisted retrolabyrinthine approach under reinforced continuous intraoperative monitoring for preservation of hearing and facial nerve function. However, the hearing preservation rate was relatively low in patients with long-wave V latency in the auditory brainstem response or poor otoacoustic emission response under this approach. Thus, the hearing preservation rate in such patients remains to be improved. To overcome this limitation, we modified the previous approach. In 26 of the 33 consecutive cases (79%) over the last three years, preservation of hearing equivalent to that before surgery or improved hearing was achieved. Postoperative deafness was observed in only two of the 33 cases (6%). According to previous reports, the rate of hearing preservation using the retrolabyrinthine approach is approximately 30-50%. Therefore, we have achieved a higher hearing preservation rate than that previously reported using the endoscopy-assisted retrolabyrinthine approach under reinforced continuous intraoperative monitoring. These improvements in our department are considered to be helpful for hearing preservation.

Efficacy of Resection of Lateral Wall of Endolymphatic Sac for Treatment of Meniere's Disease

Background

To explore the long-term efficacy and safety of resection of the lateral wall of the endolymphatic sac for the treatment of intractable Meniere's disease (MD) as an alternative surgical procedure for treating this disorder.

Methods

Data from 73 patients who were referred to our hospital and diagnosed with unilateral MD between January 2015 and June 2019 were retrospectively analyzed in this study. Seventy-three patients who had frequent vertigo even after receiving standardized conservative treatment for at least half a year underwent resection of the lateral wall of the endolymphatic sac. Vertigo control and auditory function were assessed. Pure tone audiometry, caloric test, and vestibular evoked myogenic potential were performed to evaluate audiological and vestibular functions. The post-operative follow-up duration was more than 2 years.

Results

Among the 73 patients (male 34 cases, female 39 cases; age 20–69 years, average 51.4), vertigo was controlled effectively for 66 cases (90.4%) after 2 years of follow-up; 45 cases (61.6%) were completely controlled, and 21 cases (28.8%) were substantially controlled in this study. The patients of 16.4% had hearing loss with more than 10 dB change based on the four-tone average (0.5, 1, 2 and 3 kHz). No patient had a facial nerve weakness, cerebrospinal fluid leakage, or other complications.

Conclusion

Resection of the lateral wall of the endolymphatic sac, which can effectively control vertiginous symptoms in intractable MD patients, represents an effective and safe therapy for this disease. Resection of the lateral wall of the endolymphatic sac is expected to be used as an alternative treatment for MD.

The combined TL-RS approach: Advantages and disadvantages of working 360 degrees around the sigmoid sinus

Abstract Objective: To highlight the advantages and disadvantages of the combined translabyrinthine (TL) and classic retrosigmoid (RS) approach. Design: Retrospective chart review. Setting: National Tertiary Referral Center for skull base pathology. Participants: Twenty-two patients with very large cerebellopontine angle tumors were resected using the combined TL-RS approach. Main outcome measures: Preoperative patient characteristics, including age, sex, and hearing loss. Tumor characteristics, pathology, and size. Intraoperative outcome: Tumor removal. Postoperative outcomes included facial nerve function, residual tumor growth, and neurological deficits. Results: Thirteen patients had schwannoma, eight had meningioma, and one had both. The mean age was 47 years, mean tumor size was 39 × 32 × 35 mm (anterior-posterior, medial-lateral, craniocaudal), and mean follow-up period was 80 months. Tumor control was achieved in 13 patients (59%), and nine (41%) had residual tumor growth that required additional treatment. Seventeen patients (77%) had postoperative HouseBrackmann (HB) facial nerve function grade 12, one had HB grade 3, one HB V, and three HB VI. Conclusion: Combining TL and RS approach may be helpful in safely removing large meningiomas and schwannomas in selected cases. This valuable technique should be considered when sufficient exposure cannot be achieved with the TL or RS approach alone.

Anatomic Assessment of the Limits of an Endoscopically Assisted Retrolabyrinthine Approach to the Internal Auditory Canal

Objective  Data regarding the surgical advantages and anatomic constraints of a hearing-preserving endoscopic-assisted retrolabyrinthine approach to the IAC are scarce. This study aimed to define the minimum amount of retrosigmoid dural exposure necessary for endoscopic exposure of the IAC and the surgical freedom of motion afforded by this approach. Methods  Presigmoid retrolabyrinthine approaches were performed on fresh cadaveric heads. The IAC was exposed under endoscopic guidance. The retrosigmoid posterior fossa dura was decompressed until the fundus of the IAC was exposed. Surgical freedom of motion at the fundus was calculated after both retrolabyrinthine and translabyrinthine approaches. Results  The IAC was entirely exposed in nine specimens with a median length of 12 mm (range: 10-13 mm). Complete IAC exposure could be achieved with 1 cm of retrosigmoid dural exposure in eight of nine mastoids. For the retrolabyrinthine approach, the median anterior-posterior surgical freedom was 13 degrees (range: 6-23 degrees) compared with 46 degrees (range: 36-53 degrees) for the translabyrinthine approach ( p  = 0.014). For the retrolabyrinthine approach, the median superior-inferior surgical freedom was 40 degrees (range 33-46 degrees) compared with 47 degrees (range: 42-51 degrees) for the translabyrinthine approach ( p  = 0.022). Conclusion  Using endoscopic assistance, the retrolabyrinthine approach can expose the entire IAC. We recommend at least 1.5 cm of retrosigmoid posterior fossa dura exposure for this approach. Although this strategy provides significantly less instrument freedom of motion in both the horizontal and vertical axes than the translabyrinthine approach, it may be appropriate for carefully selected patients with intact hearing and small-to-medium sized tumors involving the IAC.

Hearing preservation/rehabilitation surgery for small vestibular schwannoma: preliminary experience with the presigmoid retrolabyrinthine approach

BACKGROUND

The presigmoid retrolabyrinthine approach (PRA) for small vestibular schwannoma (VS) has unique advantages. Combination with partial labyrinthectomy further makes up its defect of high demand for anatomy.

OBJECTIVE

Aimed to describe our use of the PRA with partial labyrinthectomy in VS surgery.

METHODS

We retrospectively analyzed 10 patients diagnosed with VS who underwent PRA between September 2017 and November 2020. Their perioperative data were analyzed.

RESULTS

Six tumors were on the left and three were on the right. One case was due to neurofibromatosis type 2 with bilateral involvement and underwent internal auditory canal decompression by PRA without tumor removal; all other patients underwent total tumor resection. Four patients underwent cochlear implantation simultaneously because of hearing loss that was detected during surgery. Three patients underwent partial labyrinthectomy. Five patients achieved hearing preservation, and one experienced hearing improvement. One of the three patients who underwent partial labyrinthectomy maintained hearing. All patients' pre- and postoperative facial nerve functions were House-Brackmann grade I. After a median follow-up time of 13 months, no tumors recurred.

CONCLUSIONS

PRA for small VS is a safe and effective surgery that can achieve facial nerve and hearing preservation. Combination with partial labyrinthectomy can also preserve hearing.

Extended Retro/Infralabyrinthine Approach to Cerebellopontine Angle and Internal Auditory Canal, a Radio-Anatomic Study

INTRODUCTION

There is a considerable controversy about approaches that preserve hearing in acoustic neuroma surgery. Transtemporal approaches have the advantage of extradural drilling and minimal cerebellar retraction. We aimed to measure the limits and exposure of extended infra/retrolabyrinthine approach using temporal bone dissection and temporal high resolution computed tomography (HRCT).

MATERIALS AND METHODS

Hundred temporal bone sides (unpaired) underwent HRCT. The images were used to estimate the limits and exposure of infra/retrolabyrinthine approach. Also, 10 temporal bone sides underwent the same imaging protocol then were dissected to measure actual exposure and limits of dissection. These measures were compared with those retrieved by HRCT to find if they are appropriate to be applied in general population.

RESULTS

Mean posterior fossa angle of vision (24.5 degrees), retrolabyrinthine (internal auditory canal) IAC (58.6%), and infralabyrinthine IAC exposures (73.2%) were documented based on data retrieved from CT scan. After temporal bone dissection, posterior fossa (p = 0.139) and infralabyrinthine exposures (p = 0.674) were not statistically different comparing with measures retrieved from CT scan; however, retrolabyrinthine exposure was overestimated (p = 0.012).

CONCLUSION

We found that at least 20% more of IAC length can be exposed by extension of retrolabyrinthine to infralabyrinthine dissection. Infralabyrinthine exposure can be estimated preoperatively using temporal bone CT but the same is not true for retrolabyrinthine exposure.

Simultaneous supervision by microscope of endoscope-assisted microsurgery via presigmoid retrolabyrinthine approach: A pilot study

OBJECTIVE

To examine the impact of integrated hybrid operating rooms for endoscope-assisted microsurgery using the presigmoid retrolabyrinthine (RL) approach, and to determine the value of simultaneous supervision of skull base endoscopic procedures by microscope.

MATERIAL AND METHODS

We retrospectively reviewed endoscope-assisted surgery using the RL approach at our institution between September 2013 and January 2017. The simultaneous supervision of endoscopic procedures by microscope was realized using the integrated hybrid system. Intra- or postoperative complications and surgical outcomes were analyzed. All patients were followed for at least 1 year.

RESULTS

In total, 32 patients were studied: 4 vestibular schwannomas, 5 cholesteatomas, 8 hemifacial spasms, 5 glossopharyngeal neuralgias, and 10 Ménière's disease. In patients with vestibular schwannoma or cholesteatoma, complete removal was performed in all patients. In patients with Ménière's disease, hemifacial spasm or glossopharyngeal neuralgia, satisfactory symptom relief was achieved in all patients. Two (6.3%) patients had hearing loss after surgery which did not recover. One (3.1%) patient with vestibular schwannoma had mild facial palsy (HB III) at 2 weeks after the operation and recovered to near normal facial nerve function (HB II) at 1 year after surgery. No permanent or transient dysfunction of the trigeminal nerve or the lower cranial nerves was observed during follow-up. No complications such as cerebrospinal fluid (CSF) leakage or meningitis were observed.

CONCLUSION

The endoscope provided a clearer and larger view, which solved the limitations of surgery using the RL approach. Endoscopic surgery under simultaneous supervision by microscope was safe and efficient in hearing preservation as well as in preservation of facial nerve function. An integrated operation room provided better support and the ability to switch quickly between these various complex devices.

Endoscopically Assisted Drilling, Exposure of the Fundus through a Presigmoid Retrolabyrinthine Approach: A Cadaveric Feasibility Study

The presigmoid retrolabyrinthine approach to the cerebellopontine angle is traditionally described to not provide access to the internal auditory canal (IAC). We aimed to evaluate the extent of the IAC that could be exposed with endoscopically assisted drilling and to measure the percentage of the IAC that could be visualized with the microscope and various endoscopes after drilling had been completed. Presigmoid retrolabyrinthine approaches were performed bilaterally on 4 fresh cadaveric heads. We performed endoscopically assisted drilling to expose the fundus of the IAC, which resulted in exposure of the entire IAC in 8 of 8 temporal bone specimens. The microscope afforded a mean view of 83% (n = 8) of the IAC. The 0°, 30°, 45°, and 70° endoscope each afforded a view of 100% of the IAC in 8 of 8 temporal bone specimens. In conclusion, endoscopic drilling of the IAC of can provide an extradural means of exposing the entire length of the IAC while preserving the labyrinth.

Total Facial Paralysis after Vestibular Schwannoma Surgery: Probability of Regaining Normal Function

The aim of the present study was to ascertain the precise fraction of vestibular schwannoma cases that recover to normal function after postoperative total facial nerve paralysis and to compare our results with those presented in the literature. This was a retrospective case review of 631 cases. Among the 132 cases with immediate postoperative facial nerve palsy (House Brackmann [HB] grade VI), only 2 (1.5%) recovered to normal function (HB grade I). In an attempt to compare our results with those of other series in the literature, we found a large variation in the incidence of recovery of this group of patients to grade I, ranging from 0% to 50%. Our analysis of the reported data revealed widely varying methods of data collection and presentation, making a scientifically valid comparison particularly difficult. According to our data, complete (HB grade I) or near-complete (HB grade II) facial nerve function recovery from an immediate postoperative grade VI palsy is extremely rare.

Endolymphatic duct blockage: quality of life assessment of a novel surgical technique for Ménière disease

The aim of this study is to evaluate the quality of life (QOL) of patients treated by endolymphatic duct blockage (EDB) for Ménière's disease with a dedicated questionnaire. This is a retrospective cross-sectional study which included 54 patients diagnosed with severe, refractory Ménière's disease according to the AAO-HNS criteria and treated with EDB between 2010 and 2013. Answers to the first 38 questions have assigned scores from 0 to 4 (0 corresponding to the poorest QOL). A preoperative score called S1 was calculated as follows: S1 = sum of preoperative question scores/maximum possible preoperative score ×100. The same formula was used to calculate the postoperative score S2. The change in QOL score, S3, was then calculated (S3 = S2-S1). All answers were analyzed anonymously. Statistical analysis was done using Student t test and Chi square test. A response rate of 89 % was obtained with the Ménière's disease outcome questionnaire. The preoperative (S1) score was 21.4 (±12.6) and the postoperative score (S2) was 64.6 (±21.6) with a change in QOL (S3) of 43.3 (p < 0.001). Postoperatively, 89.9 % reported no Ménière's attacks (p < 0.001). Seventy-nine percent (15/19) of the questions showed a significant improvement after surgery. These results show that EDB is associated with a significant improvement of the QOL of patients suffering from severe Ménière's disease.

Endolymphatic duct blockage: a randomized controlled trial of a novel surgical technique for Ménière's disease treatment

OBJECTIVES

To compare the effectiveness of the endolymphatic duct blockage (EDB) and the endolymphatic sac decompression (ESD) to control Ménière's disease symptoms and to evaluate their effect on hearing level.

STUDY DESIGN

Prospective nonblinded randomized study.

SETTING

Tertiary medical center.

SUBJECTS AND METHODS

Fifty-seven patients affected by a refractory Ménière's disease were included out of which 22 underwent an ESD and 35 underwent an EDB. Five periods of follow-up were considered: 0 to 1 week, 1 week to 6 months, 6 to 12 months, 12 to 18 months, and 18 to 24 months. Mean outcome measurements consisted of vertigo control, tinnitus, aural fullness, instability, and hearing level. Hearing level was evaluated using pure-tone average (PTA) and speech discrimination score (SDS).

RESULTS

There was no significant difference between the 2 groups in the number of vertigo spells per months preoperatively (P = .153). Twenty-four months postoperatively, 96.5% of the EDB group had achieved a complete control of vertigo spells against 37.5% of the ESD group with a statistically significant difference (P = .002). There was a better control of tinnitus and aural fullness with EDB (P = .021 and P = .014, respectively). There was no statistically significant difference in hearing level preoperatively (P = .976) and 24 months postoperatively (P = .287) between the 2 groups. Hearing level was preserved in each group with no significant difference between the preoperative and the postoperative levels (P > .05).

CONCLUSION

EDB is more effective than the traditional ESD in controlling the symptoms of Ménière's disease. It is a novel surgical technique with promising results for a complete treatment of Ménière's disease. There are no significant complications or adverse effect.

The intracranial facial nerve as seen through different surgical windows: an extensive anatomosurgical study

BACKGROUND

The facial nerve has a short intracranial course but crosses critical and frequently accessed surgical structures during cranial base surgery. When performing approaches to complex intracranial regions, it is essential to understand the nerve's conventional and topographic anatomy from different surgical perspectives as well as its relationship with surrounding structures.

OBJECTIVE

To describe the entire intracranial course of the facial nerve as observed via different neurosurgical approaches and to provide an analytical evaluation of the degree of nerve exposure achieved with each approach.

METHODS

Anterior petrosectomies (middle fossa, extended middle fossa), posterior petrosectomies (translabyrinthine, retrolabyrinthine, transcochlear), a retrosigmoid, a far lateral, and anterior transfacial (extended maxillectomy, mandibular swing) approaches were performed on 10 adult cadaveric heads (20 sides). The degree of facial nerve exposure achieved per segment for each approach was assessed and graded independently by 3 surgeons.

RESULTS

The anterior petrosal approaches offered good visualization of the nerve in the cerebellopontine angle and intracanalicular portion superiorly, whereas the posterior petrosectomies provided more direct visualization without the need for cerebellar retraction. The far lateral approach exposed part of the posterior and the entire inferior quadrants, whereas the retrosigmoid approach exposed parts of the superior and inferior quadrants and the entire posterior quadrant. Anterior and anteroinferior exposure of the facial nerve was achieved via the transfacial approaches.

CONCLUSION

The surgical route used must rely on the size, nature, and general location of the lesion, as well as on the capability of the particular approach to better expose the appropriate segment of the facial nerve.

[Posterior petrosal approach - analysis of the surgical technique in cadavers simulation]

The aim of the study was to present consecutive stages of the posterior petrosal approach (PPA). Eighteen simulations of PPA were performed on non-fixed human cadavers without any known pathologies in the head and neck. The consecutive stages of the procedure were documented with photographs and schemes. The starting point for PPA is a temporal craniotomy, suboccipital craniectomy and mastoidectomy with keeping the bony labyrinth intact. Approach to the middle part of the clivus is achieved by raise of the temporal lobe and section of the superior petrosal sinus and tentorium and by mobilization the sigmoid sinus. Posterior petrosal approach is a reproducible technique, which provides surgical penetration of the middle clivus and related regions. It reduces the operating distance and allows to limit the cerebellum and temporal lobe traction and to preserve the anatomic integrity of the brain stem and cranial nerves of the cerebellopontine angle.

Facial nerve outcome after vestibular schwannoma surgery: our experience

In this study we evaluate the postoperative facial nerve function after vestibular schwannoma (VS) surgery and analyze the factors that cause it. We included 97 consecutive patients undergoing surgical excision of sporadic unilateral VS. Patient and tumor characteristics, surgical approaches, facial nerve function, extent of tumor removal, perioperative complications are all analyzed through standardized systems. Four different surgical approaches are used: translabyrinthine, retrolabyrinthine, retrosigmoid, and middle cranial fossa. Anatomic preservation of the facial nerve is achieved in 97% of patients. The incidence of postoperative facial palsy is found to be statistically correlated to tumor size, but not to the surgical approach used and to extent of tumor penetration in the internal auditory canal. A significant improvement of the short-term facial nerve outcome is detected in patients undergone simultaneous intraoperative electromyography (EMG) and pneumatic facial nerve monitoring. Complete tumor excision is achieved in 94% of cases. Complication rates are excellent and no deaths are reported. Short- and long-term facial nerve outcome is good and comparable with those of other series reported in literature. In VS surgery both EMG and pneumatic facial nerve monitors should be simultaneously used. Further investigations are desirable to improve the facial outcome respecting the oncological radicality.

Stage II vestibular schwannoma: predictive factors for postoperative hearing loss and facial palsy

OBJECTIVES

To assess predictive factors for deafness and facial palsy after vestibular schwannoma surgery on a translabyrinthine or retrolabyrinthine approach, and to compare sequela results to those for gamma knife radiosurgery.

PATIENTS AND METHODS

A retrospective study included 70 patients operated on for stage II vestibular schwannoma (Koos classification). Postoperative hearing was assessed on pure-tone average and speech discrimination score, and facial palsy on the House and Brackmann classification, preoperatively and at 1 year postoperatively. Various predictive factors were assessed for both. Statistical analysis used the Fischer exact test, with a significance threshold of P<0.05.

RESULTS

Hearing was conserved in 18.9% of patients operated on with a retrolabyrinthine approach, with 8.1% conserving useful hearing. Facial function was conserved in 91.4%. Predictive factors for hearing conservation did not achieve statistical significance, but showed trends for: preoperative pure-tone average threshold≤30dB and speech discrimination score≥ 70%, age less than 55 years, tinnitus, nearly normal auditory brainstem response (ABR) latency, and homogeneous tumor on MRI. Predictive factors for conserved facial function likewise did not achieve statistical significance, but showed trends for: age less than 55 years, deafness of progressive onset, absence of cardiovascular risk factors, nearly normal ABR latency and tumor size<13.5mm on MRI.

CONCLUSION

Facial nerve risk is largely the same with surgery or gamma knife radiosurgery. Concerning hearing, gamma knife radiosurgery seems to provide better hearing conservation, but only over the short term.

A comparative anatomic study of a modified temporal-occipital transtentorial transpetrosal-ridge approach and a transpetrosal presigmoid approach

OBJECTIVE

To evaluate the anatomic features of a modified temporal-occipital transtentorial transpetrosal-ridge approach versus the conventional approach for surgery of petroclival tumors.

METHODS

The conventional transpetrosal presigmoid approach or the modified temporal-occipital transtentorial transpetrosal-ridge approach was performed on different sides of the heads from 10 adult Chinese cadavers to compare incision site, exposure area, and operating space.

RESULTS

In the modified approach, only medial and median parts of the petrous ridge were removed. No significant differences in maximal visual angle and operative depth were found between the two approaches (P > 0.05). The modified approach required a much smaller bone window compared with the presigmoid approach. The exposure in the middle of the ventral brainstem in the modified approach was much greater than in the presigmoid approach. The angle required for exposure of the temporal lobe via the ventral medulla oblongata in the modified approach was much smaller than in the presigmoid approach (P < 0.05).

CONCLUSIONS

The modified temporal-occipital transtentorial transpetrosal-ridge approach is a feasible surgical approach to remove petroclival tumors.

Beyond audiofacial morbidity after vestibular schwannoma surgery

Object

Outcomes following vestibular schwannoma (VS) surgery have been extensively described; however, complication rates reported in the literature vary markedly. In addition, the majority of reports have focused on outcomes related to cranial nerves (CNs) VII and VIII. The objective of this study was to analyze reported morbidity unrelated to CNs VII and VIII following the resection of VS.

Methods

The authors performed a comprehensive search of the English language literature, identifying and aggregating morbidity and death data from patients who had undergone microsurgical removal of VSs. A subgroup analysis based on surgical approach and tumor size was performed to compare rates of CSF leakage, vascular injury, neurological deficit, and postoperative infection.

Results

One hundred articles met the inclusion criteria, providing data for 32,870 patients. The overall mortality rate was 0.2% (95% CI 0.1–0.3%). Twenty-two percent of patients (95% CI 21–23%) experienced at least 1 surgically attributable complication unrelated to CNs VII or VIII. Cerebrospinal fluid leakage occurred in 8.5% of patients (95% CI 6.9–10.0%). This rate was markedly increased with the translabyrinthine approach but was not affected by tumor size. Vascular complications, such as ischemic injury or hemorrhage, occurred in 1% of patients (95% CI 0.75–1.2%). Neurological complications occurred in 8.6% of cases (95% CI 7.9–9.3%) and were less likely with the resection of smaller tumors (p < 0.0001) and the use of the translabyrinthine approach (p < 0.0001). Infections occurred in 3.8% of cases (95% CI 3.4–4.3%), and 78% of these infections were meningitis.

Conclusions

This study provides statistically powerful data for practitioners to advise patients about the published risks of surgery for VS unrelated to compromised CNs VII and VIII.

Transpetrosal approaches for meningiomas of the posterior aspect of the petrous bone

OBJECTIVE

To assess outcome following excision of meningiomas of the posterior aspect of the petrous bone through transpetrosal approaches.

MATERIAL AND METHOD

We carried out a retrospective case-series study in a multidisciplinary tertiary care center on all patients who underwent meningiomas removal from January 1989 to September 2005. Surgical approaches were transpetrosal: widened retrolabyrinthine, translabyrinthine, transotic and transcochlear, occasionally combined with a subtemporal transtentorial approach. Epidemiology, symptoms, preoperative evaluation, surgery, postoperative complications and facial and auditory results were analyzed using standardized grading systems. The Desgeorges and Sterkers classification was used to assess tumor size and location.

RESULTS

Forty women and three men underwent surgery (mean age: 56.7). Medium-sized tumors stages 2 and 3 (84%) and AM and P localization (34% and 20.4%) predominated. In 65% of cases, the tumor extended beyond the CPA. Main presenting symptoms were balance disorders (72%) and sensorineural hearing loss (53.5%). Mortality was nil. A preoperative facial nerve paresis was present in 14% of patients. Tumor removal was complete in 79.1% of cases. At 1-year post-op, 73% of patients had a normal or subnormal facial function and 55% had serviceable hearing. A cerebrospinal fluid leakage occurred in 6.9%.

DISCUSSION

Posteriorly attached meningiomas are less symptomatic and of better prognosis than medially inserted ones. Transpetrosal approaches are reliable for the removal for all types and sizes of such tumors, and can be easily combined in the same procedure with a subtemporal transtentorial approach to remove extensions to the clivus and tentorium. They offer low morbidity and a high proportion of facial nerve and hearing preservation.

Symptomatic subdural hygroma and temporal lobe edema after translabyrinthine removal of acoustic neuroma

The translabyrinthine approach is familiar to most neurosurgeons and neuro-otologists and is frequently used to remove acoustic neuromas. Some of the complications associated with this surgery include cerebrospinal fluid (CSF) leaks, meningitis, and rarely fat graft prolapse. The authors report a 60-year-old woman who underwent a translabyrinthine approach and microsurgical resection of a right-sided 1-cm acoustic neuroma. Initially, she was discharged home after an uneventful postoperative course. Four days later, she sought treatment in the emergency room complaining of headaches, dizziness, and lethargy. A computed tomographic (CT) scan showed a large right-sided subdural hygroma and right temporal lobe edema. The patient underwent burr hole evacuation of the collection and placement of a subdural drain, after which the edema in the temporal lobe and hygroma resolved. We speculate that the underlying mechanism was the result of inadvertant damage to the venous drainage and an arachnoid tear that was not appreciated during surgery. Neurosurgeons and neuro-otogists should be aware of this unusual complication of translabyrinthine surgery and its possible underlying mechanisms.

Avantages de l’abord rétro-labyrinthique pour l’exérèse des méningiomes insérés au pourtour du coude du sinus latéral

PURPOSE

To describe the retrolabyrinthine approach for the resection of 9 meningiomas inserted around the lateral sinus between the transverse and sigmoid parts, to discuss the value of this approach compared to the retrosigmoid approach for resection of meningioma in this localization and to review the literature.

METHODS

Retrospective study. Between 1988 and 2002, 9 patients (8 female, mean age 50 years) underwent surgery via the retrolabyrinthine approach for resection of meningiomas inserted around the lateral sinus between the transverse and sigmoid parts.

RESULTS

Resection was total (8 Simpson I and 1 Simpson II) in all patients. In the early postoperative course, one patient was treated for meningitidis with an LCR leak and one patient present a temporary paresis of the vagus nerve. Mean follow-up was 5 years (6 months-10 years). All patients continued their pre-treatment occupation after surgery. No recurrence was observed.

CONCLUSION

Two approaches can be used for resection of meningiomas in this localization. The retrosigmoid approach is a common neurosurgical approach exposure of the cerobellopontine angle. It is practised by most neurosurgeons. Via this approach, the cerebellar lobe must be pushed back so the arteries feeding the tumor are in the operative field at the end of the procedure. For numerous authors the operative field is too narrow. On the other hand, the retrolabyrinthine approach described in 1972 by Hitselberger and Pulec allows exposure of feeding arteries during the first steps of operation, an easier resection of meningioma insertion and better control of the lateral sinus. This approach can be enlarged to the retrosigmoid or the subtemporal anatomic region.

Twenty years' experience in the treatment of acoustic neuromas with fractionated radiotherapy: a review of 45 cases

PURPOSE

To evaluate very long-term results of fractionated radiotherapy (FRT) of acoustic neuromas (AN).

METHODS AND MATERIALS

From January 1986 to January 2004, FRT was performed in 45 consecutive patients (46 AN). Indications were as follows: poor general condition contraindicating surgery, hearing preservation in bilateral neuromas, partial resection, nonsurgical recurrence. A 3-field to 5-field technique with static beams was used. A mean total dose of 51 Gy was given (1.80 Gy/fraction). The median tumor diameter was 31 mm (range, 11-55 mm). The median follow-up from FRT was 80 months (range, 4-227 months).

RESULTS

The particularity of our series consists of a very long-term follow-up of FRT given to selected patients. Nineteen patients died, two with progressive disease, and 17 from non-AN causes. A serviceable level of hearing was preserved in 7/9 hearing patients. No patient had facial or trigeminal neuropathy. Tumor shrinkage was observed in 27 (59%) and stable disease in 16 (35%). Tumor progression occurred in three patients, 12 to 15 months after FRT. Two additional tumors recurred after shrinkage 20 and 216 months after treatment and were operated on. Actuarial local tumor control rates at 5 and 15 years were 86%. For the patient who had a tumor recurrence at 216 months, histologic examination documented transformation to a low-grade malignant peripheral nerve sheath tumor.

CONCLUSION

Very long-term efficacy of FRT is well documented in this series. However, our results suggest that malignant transformation can occur many years after FRT so we advocate caution when using this treatment for young patients.

Retrolabyrinthine craniectomy: the unsung hero of skull base surgery

Despite being the foundation of, or supplement to, many skull base exposures, the retrolabyrinthine approach has not been adequately illustrated in the skull base literature. As an aid to skull base surgeons in training, this article provides a step-by-step description of the microsurgical anatomy and operative nuances of this important technique.

Surgery of cerebellopontine angle epidermoid cysts: role of the widened retrolabyrinthine approach combined with endoscopy

OBJECTIVES

To evaluate the use of the retrolabyrinthine approach (RLA) combined with endoscopy with particular reference to preservation of cranial nerve function and completeness of excision in surgery of epidermoid cysts.

METHODS

A retrospective study was performed on a series of 8 consecutive patients of whom 7 have undergone surgery. Main outcome measures Measures include audiological and neurological status preoperatively and postoperatively, size of the lesion, the surgical approach, completeness of excision, and operative morbidity.

RESULTS

The tumors were all large, ranging from 2 x 3 cm to 6 x 6 cm. Presenting symptoms were headache (75%), dysequilibrium (62%), trigeminal nerve palsy (38%), abducens nerve palsy (25%), and, rarely, auditory symptoms. Seven patients underwent surgery, 5 by the RLA, 1 by a translabyrinthine approach (TLA), and 1 by a transcochlear approach. Complete excision was achieved in 5 of the 7 patients. A transtentorial approach was combined in 2 cases (1 RLA, 1 TLA). Endoscopy was used in 3 cases. It allowed a complete tumor excision. One case of keratinous meningitis was observed. Trigeminal nerve function returned to normal in all patients. Postoperative facial nerve function was grade I in 5 cases and grade III in 2 cases. Hearing was preserved in 3 cases as class A, 1 case as class B. In the 2 cases presenting with abducens nerve palsy preoperative symptoms were initially aggravated before returning to normal function by 1 year postoperatively. The RLA with endoscopy allowed less invasive surgery and preservation of hearing in 4 of the 5 cases where it was attempted. Tumor control appeared better than with the suboccipital approach. Mortality and postoperative morbidity also appear reduced.

CONCLUSION

RLA combined with endoscopy should be considered as the standard approach for excision of epidermoid cysts. Extension of this approach into a TLA or transcochlear approach will depend on preoperative difficulties and preoperative hearing.

Vestibular schwannoma surgery outcomes: our multidisciplinary experience in 400 cases over 17 years

OBJECTIVES/HYPOTHESIS

The aim of the study was to evaluate the incidence of short- and intermediate-term postoperative complications after vestibular schwannoma surgery.

STUDY DESIGN

Retrospective review in a tertiary referral center.

METHODS

In 400 patients who underwent surgical removal of vestibular schwannoma from 1984 to 2000,symptoms, preoperative evaluation, surgery, and postoperative complications were analyzed using standardized grading systems.

RESULTS

One hundred ninety-four men and 206 women had an operation. Mean age was 53.9 years (age range, 11-78 y). Tumor size according to Koos stage was stage 1 in 39 cases, stage 2 in 122 cases, stage 3 in 87 cases, and stage 4 in 152 cases. Preoperatively, 7.5% of patients had facial nerve dysfunction. Surgical approaches were translabyrinthine in 229 patients, widened retrolabyrinthine in 128 cases, suboccipital in 42 cases, and transotic in 1 case. Mortality was 0.5%. Facial nerve was transected in 15 cases (3.7%) and immediately repaired in 5 cases. A delayed hypoglossal-to-facial nerve anastomosis was performed in 12 cases. At 1 year, House-Brackmann grade in 70.7% of patients was 1 to 2; in 24.3%, 3 to 4; and in 5%, 5 to 6. Poor facial nerve outcome was correlated with tumor size, preoperative irradiation, and nerve dysfunction and was not correlated with the approach used. Most patients had postoperative dizziness, and 30% still had vestibular disturbances after 1 year. Nine patients (2.2%) had a cerebrospinal fluid rhinorrhea, and 24 had a cerebrospinal fluid wound leak (6%). Twenty-two patients (5.5%) had postoperative meningitis. Two patients had a cerebellopontine angle hemorrhage, and three a brainstem infarct.

CONCLUSION

Transpetrosal approaches (translabyrinthine, widened retrolabyrinthine) are safe for vestibular schwannoma removal, and rates of postoperative complications and sequelae are decreasing.

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.

The transmastoid retrolabyrinthine approach in vestibular schwannoma surgery

OBJECTIVE

We conducted a prospective analysis of 22 patients with small vestibular schwannoma and useful hearing who were operated on via a transmastoid retrolabyrinthine approach between January 1994 and March 1999.

PATIENTS AND METHODS

The average age was 35 years, and there were 14 females and 8 males. All patients had unilateral tumors, with 10 of them occurring in the right ear and 12 occurring in the left ear. The following parameters were included in our protocol: total removal of the tumor, intraoperative difficulties or complications, immediate postoperative complications, facial score 10 days and 3 months after the surgery, and audiologic evaluation 90 days after the surgery.

RESULTS

A good exposure of the internal auditory canal was possible in 19 cases. In 3 patients we had to change the approach to a translabyrinthine one to achieve total removal of the tumor in all patients. Hearing was preserved at the same preoperative levels in 31% of the cases.

CONCLUSIONS

The retrolabyrinthine approach offered security to the facial nerve, no morbidity, and good percentage of hearing preservation. It is also easily changeable to a translabyrinthine approach when more exposure is necessary.

Surgical management of intratemporal lesions

In order to evaluate the decisional elements in the surgical strategy of deep-seated and/or extensive intratemporal lesions, a retrospective review of cases followed up between 1985 and 1996 in our department was undertaken. Eighty-one adult patients presenting temporal bone lesions located or extending beyond the middle ear limits excluding vestibular schwannomas and surgically treated were included. The population comprised 38 men and 43 women (mean age: 43 years, range: 17-81). Pre-, intra- and postoperative data were collected from medical files. The principal factors influencing the choice of the surgical approach were the location of the lesion and its presumed aggressiveness, the tumour involvement of the internal carotid artery and the labyrinth on preoperative imaging, and the preoperative hearing loss. A coherent algorithm based on these factors can be proposed for the surgical management of intratemporal lesions. High quality preoperative imaging is mandatory for the surgical planning.

[Fractionated irradiation of cerebellopontine angle neurinoma: 12 years' experience of the Bordeaux University Hospital Center]

PURPOSE

To evaluate retrospectively the long-term results of fractionated radiation therapy (RT) in cerebello-pontine angle neurinomas (CPA).

METHODS AND MATERIAL

From January 1986 to October 1995, 29 patients with stage III and IV neurinomas were treated with external fractionated RT. One patient was irradiated on both sides and indications for RT were as follows: (1) general contraindications for surgery (16 patients); (2) hearing preservation in bilateral neurinomas after controlateral tumor exeresis (six patients); (3) partial tumor removal (five patients); and, (4) non-surgical recurrence (three patients). A three to four fields technique with coplanar static beams and conformal cerobend blocks was used; doses were calculated on a 95 to 98% isodoses and were given five days a week for a median total dose of 51 Gy (1.8 Gy/fraction). Most patients were irradiated with 6 to 10 MV photons).

RESULTS

Median follow-up was 66 months (seven to 120 months). Seven patients died, two with progressive disease, five from non-tumoral causes. Tumor shrinkage was observed in 13 patients (43.3%), stable disease in 14 (46.6%), and tumor progression in three. Two patients underwent total tumor removal after RT (one stable and one growing tumor). Hearing was preserved in four out of six patients. No patient experienced facial or trigeminal neuropathy.

CONCLUSION

Fractionated RT is a well tolerated and efficacious treatment of large non-surgical CPA neurinomas.