Hearing preservation in acoustic neuroma surgery. Middle fossa versus suboccipital approach

Over the past few years there have been reports discussing the preservation of hearing after the removal of acoustic neuromas through the middle cranial fossa or the suboccipital approaches. This is a complex issue with many facets and controversies. In an attempt to answer at least some of these controversies, this article reviews the experience of our group. Preservation of hearing was attempted in thirty-four cases out of 220 acoustic neuromas. In twenty cases the middle fossa approach was used: All tumors were less than 2 cm from the fundus, and in four patients the tumor was bilateral. In sixteen of the twenty (80%) the cochlear nerve was spared; in ten of twenty (50%) measurable hearing was retained, but in only four (20%) was the postoperative hearing serviceable according to the 50/50 rule. In fourteen cases the suboccipital approach was used: All but two of the tumors were smaller than 2 cm. In three patients the tumor was bilateral. The cochlear nerve was preserved in ten of the fourteen cases (71.4%). Measurable hearing was present in four of fourteen cases postoperatively (28.6%); none had serviceable hearing according to the 50/50 rule. Hearing was not preserved in any bilateral tumor case. The middle fossa and the suboccipital approaches are discussed as well as the relative merits of each procedure in preservation of hearing.     

Acoustic neuroma surgery with emphasis on preservation of hearing

A review is presented of 37 cerebellopontine angle tumors surgically removed between 1973 and 1978 by the author at the New York University Medical Center. A diagnostic protocol is outlined: An acoustic PEG (small volume pneumoencephalogram with polytomography) is utilized where a medium to large tumor is suspected, and a Pantopaque fossagram for the smaller tumors. Indications are given for the middle fossa, translabyrinthine and suboccipital approaches, depending on tumor size and level of hearing. Hearing was successfully preserved at or near the preoperative level in 3 of 6 extracanalicular tumors operated upon using the suboccipital microsurgical approach. Audiometric data are given, demonstrating the preservation of hearing. The surgical technique is described. There were no fatalities in the entire series. The incidence of permanent facial nerve palsy was 8%. Nerve palsy occurred in large tumors only.     

Facial nerve hemangioma of the geniculate ganglion: An endoscopic surgical approach

Facial nerve hemangiomas are rare benign tumors arising from the venous plexus surrounding the facial nerve. Surgical management of these tumors is controversial. The goal of surgery is complete tumor removal with restoration of facial nerve function and preservation of hearing, wherever possible. The approaches most used are the translabyrinthine and middle cranial fossa approaches. In this report, we describe the first facial hemangioma treated with an endoscopic transcanal approach, combined with a retroauricular transmastoid minicraniotomy for closure of the dural defect. A great auricular nerve graft was used to reconnect interrupted nerve segments. Histopathological examination confirmed the diagnosis of a hemangioma of the first genu of the facial nerve. With magnification of the structures, the transcanal endoscopic approach allowed a radical excision of the neoplasm permitting hearing function preservation, with the possibility to work with a minimally invasive approach with respect to the labyrinthine block and cochlea. Compared to a middle cranial fossa approach, the transcanal endoscopic approach avoided labyrinthine block removal and brain retraction.     

Hearing Preservation After Acoustic Neuroma Resection With Tumor Size Used As a Clinical Prognosticator

Three hundred sixty-four patients referred to the Chicago Otology Group for acoustic tumor removal between 1981 and 1995 were reviewed in a retrospective fashion. Of this group, 60 patients were candidates for hearing preservation surgery and thus underwent one of two surgical approaches to remove the tumor and preserve hearing. Eighteen patients had tumor removal via the middle cranial fossa approach, and 42 patients had tumor removed via the retrosigmoid approach. Of the 42 patients who underwent retrosigmoid removal, 33% had hearing preserved overall. Of the 18 patients in the middle fossa group, 44% had hearing preserved overall. The average tumor size of patients with preserved hearing in the retrosigmoid group was 1.4 cm, and in the middle fossa group was 0.74 cm. Of significance was the fact that in both groups of patients with a tumor of 1.5 cm or less there was a 50% chance of hearing preservation. In the group of patients with tumors larger than 1.5 cm there was only a 16% chance of preserving hearing. We propose that these data can be used for better counseling of patients preoperatively as to the chances of hearing preservation and the type of approach appropriate for each case.     

Unilateral acoustic neuroma in childhood

Three cases of unilateral acoustic neuroma in childhood that are associated with neither neurofibromatosis type 1 nor type 2 were reported. All three cases had a hearing disorder as an initial symptom. Two of them had a large neuroma and had considerable abnormal findings in neurootological examinations, and one case with an intracanalicular tumor showed a unilateral progressive sensorineural hearing loss that had no response to steroid administration. Surgical removal of the tumor was carried out for these cases. Different approaches were used in each case; suboccipital approach, one-stage suboccipital and middle fossa approach, and middle fossa approach. Although the facial nerve functions were fairly well maintained, hearing preservation could not be attained in all. Papers dealing with this tumor were reviewed, and certain characteristics of cases with acoustic neuroma in childhood were discussed.     

Facial function in hearing preservation acoustic neuroma surgery

OBJECTIVE: To determine if facial function is worse after hearing preservation acoustic neuroma surgery (retrosigmoid and middle fossa) than in translabyrinthine surgery. DESIGN: Retrospective medical record review. SETTING: Private neuro-otology subspecialty practice of patients operated on in a tertiary care hospital. PATIENTS: This study evaluated 315 consecutive acoustic neuroma surgical procedures between April 1989 and July 1998. A total of 209 translabyrinthine procedures and 106 hearing preservation surgical procedures were performed. The hearing preservation procedures were equally divided between retrosigmoid (n = 48) and middle fossa (n = 58) procedures. METHODS: Medical records were reviewed and tabulated for tumor size, surgical approach, and House-Brackmann facial function grade at short-, intermediate-, and long-term intervals. RESULTS: Postoperative facial function in hearing preservation surgical procedures at short- and long-term follow-up was not worse than facial function after translabyrinthine surgical procedures in comparably sized tumors. CONCLUSION: Concern about postoperative facial function should not be the deciding factor in selecting hearing preservation vs nonhearing preservation acoustic neuroma surgery.     

Results of surgery by the modified extended middle cranial fossa approach in 100 patients with acoustic neuroma

The results of surgery by the middle cranial fossa (MCF) approach or the modified extended MCF approach in 100 patients with acoustic neuroma are reported. The rates of facial nerve preservation, tumor removal, and hearing preservation were reported and discussed. This surgical procedure can be applied to tumors of any size, from tumors confined to the internal auditory canal to those extending into the posterior fossa.     

Middle fossa acoustic tumor surgery: results in 106 cases

Although the middle cranial fossa approach has been used less frequently in recent years than in the past, it continues to be a useful technique for the removal of small acoustic tumors with possible hearing preservation. The approach provides complete exposure of the contents of the internal auditory canal, thus allowing positive facial nerve identification and facilitating total tumor removal. This paper reports the results of 106 middle fossa acoustic tumor removals over a 25-year period. Measurable postoperative hearing remained in 59% of cases. In 89% of cases, normal or near-normal postoperative facial nerve function was obtained. Total tumor removal was achieved in 98% of cases. Preoperative selection criteria are discussed, and postoperative complications are reported.     

Surgical exposure of the facial nerve indications and techniques.

Lesions producing facial nerve palsy may occur within the temporal bone anywhere between the internal auditory canal and the stylomastoid foramen. Surgical exposure of this nerve may be necessary for decompression, grafting, rerouting, or removal of such lesions as acoustic tumour, meningioma, facial nerve neuroma, and cholesteatoma. Contemporary surgical exposure of the facial nerve has as its aim adequate exposure of the facial nerve at any point in its course, with preservation of hearing and vestibular function, without further injury to the facial nerve and the necessity for producing a mastoid cavity. When hearing and balance function are present, the transcanal-transtympanic approach to the horizontal segment of the facial nerve offers limited access to the facial nerve in its tympanic course. Wider exposure is obtained by postauricular transmastoid exposure of the tympanic and mastoid portions of the facial nerve. The middle fossa approach to the facial nerve offers access to the internal auditory canal and labyrinthine portions of the nerve, whereas the retrolabyrinthine approach offers access to the facial nerve in the posterior fossa. Total facial nerve exposure with preservation of hearing and balance function is obtained by the combined transmastoid and middle cranial fossa approach. In individuals who have lost all function of hearing and balance, the postauricular translabyrinthine approach offers total exposure of the facial nerve within the temporal bone and posterior fossa. The aim of this discussion was to present in succinct fashion a systematized approach to surgical exposure of the facial nerve within the temporal bone and posterior fossa.     

Function-saving microsurgery in suboccipital removal of large acoustic neuromas

Various successful approaches are available for acoustic neurinoma surgery, permitting total tumor removal and preservation of cranial nerve function. In smaller and medium sized tumors excellent results can be achieved with respect to facial and cochlear nerve function using the transtemporal approach. For larger tumors similar results can be achieved by the suboccipital approach. The results of 45 completely removed large acoustic neurinomas all operated upon via the suboccipito-lateral approach with microsurgical techniques and neurophysiological monitoring are presented. The average tumor size, excluding the portion within the internal auditory canal was 3 cm. Anatomical preservation of the VIIth cranial nerve was achieved in nearly all cases. Satisfactory to excellent facial nerve function was preserved in 70% of all cases. Initial hearing was preserved in 29%. However delayed postoperative hearing loss was encountered in 13%. Therefore definite hearing preservation was achieved in 16% of the cases. Intraoperative monitoring, especially of auditory evoked potentials, was very helpful in achieving these functional results.     

Adjunctive use of endoscopy during acoustic neuroma surgery.

OBJECTIVE/HYPOTHESIS: In specific clinical situations, endoscopes offer better visualization than the microscope during acoustic neuroma (vestibular schwannoma) surgery and can therefore decrease the incidence of the postoperative complications of cerebrospinal fluid (CSF) leakage and recurrence of tumor. This study was undertaken to determine if the use of adjunctive endoscopy provides complementary information to the operating surgeon during surgery for acoustic neuromas. METHOD: Seventy-eight patients with acoustic neuromas underwent tumor excision by two neurotologists (PAW., D.S.P.), together with their respective neurosurgical partners, via a retrosigmoid (suboccipital) approach (n = 68), translabyrinthine approach (n = 7), or middle cranial fossa approach (n = 3). Endoscopy with a rigid glass lens endoscope was used during tumor removal to examine posterior fossa neurovascular structures, and after tumor excision to inspect the internal auditory canal (IAC), inner ear, and middle ear, depending on the approach used. One of the authors (D.S.P.) has not used adjunctive endoscopy during resections via the translabyrinthine and middle cranial fossa approaches, and therefore, these cases were excluded from the data collection and analysis. RESULTS: Complete tumor excision was achieved in 73 patients. Endoscopy allowed improved identification of tumor and adjacent neurovascular relationships in all cases. In addition, residual tumor at the fundus of the IAC (n = 11) and exposed air cells (n = 24) not seen with the microscope during retrosigmoid approaches were identified endoscopically. In one of the translabyrinthine cases, the endoscope allowed identification of open air cells not visualized with the microscope. None of the 78 patients developed CSF rhinorrhea. Incorporating the endoscope did not significantly increase operative time. CONCLUSIONS: Endoscopy can be performed safely during surgery to remove acoustic neuromas. The adjunctive use of endoscopy may offer some advantages including improved visualization, more complete tumor removal, and a lowered risk of CSF leakage.     

Surgical approaches and complications in the removal of vestibular schwannomas

Vestibular schwannomas are benign tumors that usually originate from the balance portion of cranial nerve VIII. The treatment options currently available for vestibular schwannomas include observation with serial imaging, stereotactic radiation, and microsurgical removal. Although the ultimate goal in treatment of vestibular schwannomas is preservation of life, the best option for each patient depends on symptoms, tumor size, tumor location, and the patient's general health and age. Surgical exposure of the cerebellopontine angle for removal of vestibular schwannomas can be performed safely via a translabyrinthine, retrosigmoid, and middle fossa approach. Each approach has its advantages and disadvantages. The goal of surgery is complete eradication of tumor with preservation of hearing and facial nerve function when possible.     

Retrosigmoid approach for acoustic tumor removal.

The retrosigmoid technique has evolved from the traditional suboccipital operation and, when combined with removal of the posterior wall of the internal auditory canal, affords a wide exposure of the cerebellopontine angle. This approach may be used for acoustic neuromas of all sizes, from intracanalicular to more than 4 cm from the porus acusticus. Hearing preservation may be attempted and is generally successful in a substantial minority of cases. The facial nerve is readily visualized at the lateral end of the internal auditory canal and is at no greater risk than in the translabyrinthine operation. We use this approach for all hearing preservation surgery as well as for tumors of more than 3 cm, regardless of hearing.     

内听道海绵状血管瘤的临床资料分析

摘要：目的探讨内听道海绵状血管瘤的诊断和治疗方法。方法回顾性分析2006年1月~2013年12月6例内听道海绵状血管瘤患者的临床资料,对患者的临床表现、影像学表现、手术方法及效果进行分析。6例患者均进行了CT与MRI检查,其中5例患者伴有面神经功能障碍,对此5例患者进行了手术治疗,对1例面神经功能正常的患者采取严密随访策略。结果6例患者术前均出现了听力下降与耳鸣,其中5例手术患者病理确诊为内听道海绵状血管瘤。手术径路包括4例迷路径路与1例颅中窝径路,术中发现肿瘤与面神经和（或）前庭蜗神经粘连,难以分离,其中3例由于肿瘤无法与面神经分离行面神经切除重建术,2例患者面神经解剖保留。术后5例患者患侧听力均丧失,术后1年行MRI复查肿瘤无残留,面神经功能均有不同程度提高。随访患者行MRI检查示肿瘤未生长。结论内听道海绵状血管瘤术前可以根据临床表现与特征性影像学表现作出诊断;相较于内听道其他常见肿瘤,海绵状血管瘤更易侵犯神经,因此手术时机的选择应更加积极;迷路径路相较于乙状窦后径路或颅中窝径路在处理内听道海绵状血管瘤上有优势,比较容易进行面神经定位与重建。     

Nerve of origin, tumor size, hearing preservation, and facial nerve outcomes in 359 vestibular schwannoma resections at a tertiary care academic center

Objective: To determine nerve of origin, tumor size, hearing preservation rates, and facial nerve outcomes in a retrospective cohort study of patients undergoing translabyrinthine (TL), middle cranial fossa (MCF), and retrosigmoid/suboccipital (SO) approaches to vestibular schwannomas (VS). Study Design: Retrospective. Methods: Chart review. Results: Patient charts from 231 TL, 70 MCF, 53 SO, and 5 combined TL/SO procedures for VS were evaluated in 356 patients. The inferior vestibular nerve (IVN) was the nerve of origin in 84 of 359 cases (23.3%), while the superior vestibular nerve (SVN) was the nerve of origin in 36 patients (10%). In 239 of 359 cases (66.6%), the nerve of origin was not identified. Forty patients undergoing hearing preservation surgery had hearing results and nerve of origin data available for review. Functional hearing (<50dB PTA and >50% speech discrimination) was preserved in 10 of 15 patients (75%) with SVN tumors, while only 7 of 25 patients (28%) with IVN tumors retained functional hearing. Facial nerve outcomes and nerve of origin were recorded simultaneously in 109 patients. Seventy‐one of 74 patients (95%) patients with IVN tumors achieved a House‐Brackmann (HB) grade I–III, while 35 of 35 patients (100%) with SVN tumors retained HB I–III facial function. Looking at tumor size versus hearing preservation, functional hearing was preserved in 22 of 49 patients (45%) with <1‐cm tumors, and 4 of 20 patients (20%) with 1‐ to 1.5‐cm tumors. For all cases with documented facial nerve function, HB I–III were achieved in 96% of SO, 94% of MCF, and 88% of TL procedures. Conclusions: Our retrospective data indicated that IVN tumors were twice as common as SVN tumors. The nerve of origin did not affect facial nerve outcomes but did impact hearing preservation rates. Patients with tumors <1 cm in size had the best chance for hearing preservation. Overall facial nerve preservation was excellent with >90% achieving HB 1 to 3 function at final follow‐up.     

The diagnosis and management of cerebellopontine angle tumors.

The diagnosis and surgical management of cerebellopontine angle tumors remains a challenge. Early detection and microsurgical technique have lowered mortality rates and have allowed surgeons to preserve facial nerve function in a high percentage of cases. The purpose of this paper is to report a series of 171 lesions removed through the middle fossa, translabyrinthine, and combined translabyrinthine-suboccipital approaches. Results and complications are covered in detail.     

Perioperative complications in acoustic neuroma (vestibular schwannoma) surgery.

OBJECTIVE: Retrospective study and review of the complications other than those related to the facial nerve and hearing, encountered in acoustic neuroma surgery. Also, an evaluation of hospital stay and its relation with various factors. STUDY DESIGN: Retrospective case review. SETTING: Tertiary neurotologic and skull base referral center. PATIENTS: A series of 707 patients who underwent surgical removal of acoustic neuroma from April 1987 to December 2001. INTERVENTIONS: The surgical approaches used were the enlarged translabyrinthine approach, the enlarged middle fossa approach, and the retrosigmoid approach. In a small number of cases, the operations were performed through other approaches. MAIN OUTCOME MEASURES: The duration of hospital stay and appearance of complications in the perioperative period along with their management. Results related to the facial nerve and hearing were not considered in this study. RESULTS: The most frequent complication was abdominal subcutaneous hematoma (site of fat harvest), which occurred in 23 patients (3.2%). Cerebrospinal fluid leak was present in 20 patients (2.8%), 15 of whom needed revision surgery. Other complications included VIth cranial nerve dysfunction in 12 cases (1.68%), subdural hematoma in 3 cases (0.4%), cerebellopontine angle hematoma in 4 cases (0.6%), cerebellar edema in 2 cases (0.28%), brainstem hematoma in 1 case (0.14%), transitory aphasia in 1 case (0.14%), and lower cranial nerve dysfunction in 1 case (0.14%). Mortality occurred in only one case (0.14%). Medical complications seldom occurred. The postoperative hospital stay ranged from 2 to 36 days, with an average of 6.4 days. The overall hospital stay diminished over time from 10.2 days in 1987 to 1990, to 4.9 days in 2001. There was a significant relation between hospital stay and tumor size, approach used, and presence/absence of complications. CONCLUSIONS: Perioperative complications in acoustic neuroma surgery do exist, but this study demonstrated how low the incidence is. The authors believe that the low percentage of complications is mainly attributable to the majority of operations being carried out in specialized clinics, where they are considered routine operations. They believe that following individualized approaches, depending on tumor size and on the preoperative function of the cranial nerves, is the proper way to reach a significant reduction in complications while maintaining a high percentage of total tumor removal. The results of this study, considered as a basis of comparison with other studies, will certainly be useful in preoperative patient counseling.     

Evaluation of Surgical Approaches to Endoscopic Auditory Brainstem Implantation

Objectives: This study investigates the use of endoscopy for the placement of an auditory brainstem implant by translabyrinthine, retrosigmoid (suboccipital), and middle cranial fossa approaches. Study Design: Cadaver dissection and endoscope-assisted placement of the auditory brainstem implant. Methods: Translabyrinthine, retrosigmoid, and middle cranial fossa dissections were performed bilaterally in five cadaveric heads. An auditory brainstem implant was placed within the lateral recess of the fourth ventricle under endoscopic visualization. The implantation was performed with all approaches and documented by digital image capture followed by production of dye-sublimation photographic prints. Results: The lateral recess was visualized with the endoscope in all three approaches to the brainstem. The 30° endoscope provided the best visualization by translabyrinthine and retrosigmoid dissection and was essential for the middle cranial fossa approach. Refinement of implant position was readily achieved, as even the deepest portion of the recess could be seen with all three approaches. Conclusions: This study finds that endoscopy provides superior visualization of the lateral recess of the fourth ventricle than the operating microscope with all approaches. The retrosigmoid approach is recommended, as it provides the best view of the implantation site and the easiest angle for placement of the prosthesis. The use of the endoscope may allow for a smaller craniotomy than with conventional microscopic techniques, depending on tumor size. The translabyrinthine approach provides a good view of the lateral recess but had no advantage over other approaches. The middle cranial fossa approach is only possible with angled endoscopes; however, it is technically the most difficult and places the facial nerve at greatest risk.     

The evolution of surgical approaches for posterior fossa meningiomas.

OBJECTIVE: To evaluate surgical outcomes for the treatment of posterior fossa meningiomas at the House Ear Clinic from 1987 to 2001. We review our current treatment algorithm and present our postoperative outcomes with attention to facial and auditory neural preservation. STUDY DESIGN: Retrospective review. SETTING: Tertiary care center. PATIENTS: Medical records of 71 patients who underwent posterior fossa meningioma surgery at the House Ear Clinic were reviewed. INTERVENTION: All patients had surgical removal of their meningioma via translabyrinthine, transcochlear, retrosigmoid, extended middle fossa, or combined petrosal approaches by House Ear Clinic neurotologists and neurosurgeons. MAIN OUTCOME MEASURES: Preoperative and postoperative auditory and facial nerve function data were collected. Patient and tumor characteristics including presenting symptoms, completion of tumor resection, and complications secondary to surgery were also recorded. RESULTS: The most common presenting symptoms in this series were otologic, with hearing loss (61%), tinnitus (58%), and imbalance (58%) as the three most common. Gross total resection was achieved in 67 (94%) patients. Hearing-preservation surgery was attempted in 37 (52%) patients (68% via extended middle fossa or combined approach). Twenty-one patients with preoperative Class A hearing had follow-up audiometric data and 18 (86%) had serviceable hearing preserved. Excluding transcochlear craniotomies, 85% of patients had normal facial nerve function postoperatively. Cerebrospinal fluid leak (6%) was the most common complication. CONCLUSIONS: Advances in microsurgical techniques have greatly changed our management of patients with posterior fossa meningiomas. These changes have reduced postoperative morbidity. Specifically, use of the anterior and posterior petrosal approaches has facilitated facial and auditory neural preservation while not compromising the extent of tumor excision.     

Posterior petrous face meningiomas: an algorithm for surgical management.

OBJECTIVE: The objective of the present study was to report our surgical strategy in the management of 81 patients with posterior petrous face meningiomas. STUDY DESIGN: Retrospective study. SETTING: This study was conducted at a quaternary private otology and cranial base center. PATIENTS: Of 139 patients with posterior fossa meningioma, 81 occurred on the posterior petrous face of the temporal bone and were the object of this study. INTERVENTIONS: Thirty-one patients were approached by the enlarged translabyrinthine approach. The enlarged translabyrinthine approach with transapical extension Type II was performedin 29 patients. The combined retrosigmoid-retrolabyrinthine approach was chosen in 8 cases. The modified transcochlear approach Type A with permanent posterior transposition of the facial nerve (FN) was performed in 6 patients. Two patients underwent a retrolabyrinthine subtemporal transapical approach. One patient underwent a transpetrous middle cranial fossa approach. Four patients with intracanalicular meningiomas were operated on through the enlarged middle cranial fossa approach. RESULTS: Total removal of the tumor (Simpson Grades I and II) was achieved in most patients (92.5%). The FN was anatomically preserved in 79 of the 81 (97.5%) patients. Five patients had less than 1 year follow-up, and 2 patients were lost to follow-up and were excluded in evaluation of the final FN outcome. At 1-year follow-up, 46 patients (63%) had Grade I to II, 19 (26%) had Grade III, 4 (5.4%) had Grade IV, 1 (1.3%) had Grade V, and 3 (4.1%) had Grade VI. Hearing-preserving surgery was attempted in 15 patients (18.5%) with preoperative serviceable hearing. Of these 15 patients, 11 had their hearing preserved at the same preoperative level, and 4 experienced postoperative deafness. Postoperatively, a new deficit of 1 or more of the lower cranial nerves was recorded in 3 patients. One patient experienced subcutaneous cerebrospinal fluid collection that required surgical management. CONCLUSION: Total tumor removal (Simpson Grades I-II) remains our treatment of choice and takes priority over hearing preservation. Subtotal resection is indicated for older and debilitated patients with giant lesions to relieve the tumor compression on the cerebellum and brainstem. Subtotal removal is also preferred in the face of the absence of a plane of cleavage between the tumor and the brainstem, in the presence of encasement of vital neurovascular structures, in elderly patients with tumors adherent to preoperatively normal facial or lower cranial nerves.