Search

Objectives: To assess facial nerve injury caused by vestibular Schwannoma compression and the adaptive ability of the nerve/muscle complex to maintain normal clinical facial function., Study Design: Prospective study., Setting: Tertiary referral centre., Patients: Thirty-four patients undergoing translabyrinthine resection of vestibular schwannoma., Intervention: Diagnostic., Main Outcome Measures: Facial nerve action potential (FNAP) amplitude recorded at the second genu enables direct assessment of motoneuron function. Comparison of FNAP amplitudes to stimulation proximal and distal to tumor compression allows calculation of motoneuron conduction block across the site of tumor compression. Recordings performed before tumor dissection from the facial nerve reflects nerve injury caused by vestibular Schwannoma compression alone. Comparison of compound muscle action potential (CMAP) amplitudes to stimulation proximal and distal to tumor compression measures motoneuron conduction block and compensatory collateral sprouting at the nerve/muscle interface. Comparison of FNAP and CMAP data demonstrates the extent of collateral sprouting, which helps maintain normal clinical facial function., Results: Normal clinical facial function is maintained when only 10% of functioning motoneurons are active. The facial nerve is highly susceptible to tumor compression with significant motoneuron injury occurring with all sizes of tumors. Motoneuron injury correlates with tumor size but with exceptions. Collateral sprouting maintains muscle function despite severe motoneuron injury. There is a significant decrease in muscle function when >80% of functioning motoneurons are in conduction block., Conclusions: The facial nerve is highly susceptible to vestibular Schwannoma compression. Collateral sprouting of active functioning motoneurons reinnervate denervated muscle fibers so maintaining muscle function and therefore clinical facial function.

Objective: This study aimed to sensitize the practitioner to the unusual presentation of basal cell carcinoma in a recurrent cholesteatoma mass., Study Design: The study design was a case report format., Setting: The study was conducted at a tertiary referral hospital., Patient: The patient studied was a contralaterally anacusic veteran., Intervention: Interventions were excision of cholesteatoma and withholding of adjunctive radiation., Conclusion: Primary basal cell carcinoma may present in a revision cholesteatoma field.

Objective: To describe characteristic features of intralabyrinthine schwannomas (ISs) that may be used to distinguish them from other otologic disorders with similar symptoms so that appropriate evaluation and management can be instituted., Study Design: This study was a retrospective case review., Setting: This study was conducted at a university-affiliated urban tertiary care medical center and a university medical center in the same city., Patients: Seven patients with ISs were included in this study., Interventions: Tumor removal versus observation and monitoring with periodic magnetic resonance imaging (MRI) scans was investigated., Main Outcome Measures: Hearing, vertigo, and tumor growth were measured., Results: Four of seven patients with ISs underwent surgical excision with no evidence of tumor recurrence. The remaining three patients are being followed-up with repeat MRI that has demonstrated minimal or no tumor growth., Conclusions: ISs can be detected in early stages if MRI is performed in patients with unilateral sensorineural hearing loss without vertiginous symptoms typical of Meniere's disease. Although complete surgical excision can be achieved readily with labyrinthectomy, observation and monitoring with rep--MRI is an option for some patients.

Hypothesis: Absent or reduced expression of schwannomin/merlin is associated with tumorigenesis of sporadic schwannomas., Background: The neurofibromatosis type 2 (NF2) gene frequently is mutated in sporadic vestibular schwannomas. The protein product of the NF2 gene is called schwannomin or merlin. Little is known about the mutated forms of schwannomin/merlin present in schwannomas., Methods: To investigate further the role of schwannomin/merlin in schwannoma tumorigenesis, immunoblotting experiments were performed. Antischwannomin/merlin-specific antibody that recognizes amino terminus of the protein was used to determine the expression levels of schwannomin/merlin in 16 sporadic vestibular schwannomas, 1 NF2-related vestibular schwannoma, and 5 spinal schwannomas., Results: The antibody detects a protein of approximately 66 kDa in the Triton X-100-insoluble fraction of tumors. The expression of schwannomin/merlin was severely reduced, <35% of control, in 11 (50%) of 22 sporadic schwannomas and in 1 NF2-related vestibular schwannoma. The intensity of 66-kDa schwannomin/merlin band was moderately reduced, from 35-60%, in 7 (32%) of 22 schwannomas compared to the expression levels found in the human brain. Truncated forms of schwannomin/merlin were identified in three tumors with moderately reduced schwannomin/merlin., Conclusions: These results provide new evidence that inactivation of schwannomin/merlin is an important factor in tumorigenesis of sporadic schwannomas.

Objective: This study aimed to review the clinicoradiographic findings in 16 patients with unilateral cochlear neuromas., Study Design: The data included in this presentation were obtained from a retrospective case review., Setting: The study was conducted at a tertiary care academic institution., Patients: Patients of any age, gender, or race with a unilateral cochlear neuroma participated., Interventions: Standard audiometric and radiographic assessment was performed., Main Outcome Measures: Progressive sensorineural hearing loss was measured., Results: Sensorineural hearing loss is out of proportion to the size of the tumor (< 8 mm in all 16 patients)., Conclusions: Gadolinium-enhanced magnetic resonance imaging in the axial and coronal planes can help identify cochlear neuromas in selected patients with unilateral sensorineural hearing loss.

Objective: The audiologic presentation of vestibular schwannoma (VS) associated with neurofibromatosis type 2 (NF2) has not been well characterized. The goal of this study was to investigate the audiologic features of NF2-associated VS and to determine their relationship to the size of the tumor., Study Design: A retrospective case review., Setting: Quaternary governmental medical research institute evaluating patients fitting specific criteria for ongoing clinical studies., Patients: Audiologic and magnetic resonance imaging data were available for 40 patients (25 males, 15 females), with an average age of 32 years, who had been recruited for ongoing clinical and genetic studies of NF2., Main Outcome Measures: The audiologic profile and magnetic resonance imaging characteristic of tumor were retrospectively reviewed., Results: The average size of the tumor at presentation was 7.26 +/- 16.58 cm3 and measured 1.2, 1.6, and 1.1 cm in the anterior/posterior, lateral/medial, and superior/inferior dimensions, respectively. An increase in lateral/medial size of the tumor most significantly correlated with deterioration in mid- (1,000-2,000 Hz) and high- (4,000-8,000 Hz) frequency hearing levels, elevated speech reception threshold, and prolonged auditory brain stem response waves III and V latency., Conclusions: Patients with NF2 demonstrate a more predictable audiologic profile for a given size tumor than has been previously described with spontaneous or sporadic VS.

Objective: This study aimed to quantify the atypical presentations of patients with vestibular schwannoma by applying the audiologic criteria for the treatment of patients to the Cambridge series of such tumors to show that clinical acumen is necessary for the effective screening of these tumors., Study Design: This study was a retrospective case review of 473 patients with vestibular schwannoma., Setting: The surgery was conducted at the Department of Otoneurological and Skull Base Surgery, University Hospital, Cambridge, a tertiary referral center., Patients: A total of 473 patients with a unilateral sporadic vestibular schwannoma were studied., Main Outcome Measures: Measured were the principal presenting symptoms and the criteria for audiologic management., Results: Of this series of patients, 89.3% had a principal presenting symptom that was typical of vestibular schwannoma (hearing loss: progressive or sudden, imbalance or tinnitus) and 10.7% had an atypical principal presenting symptom. This group of patients had significantly larger tumors (Mann-Whitney U test; tied p value = 0.0002), shorter length of history (tied p value < 0.0001), and better preserved hearing (tied p value < 0.001) than the typical otologic presentation group. These clinical correlates are related to tumor morphology, and it is hypothesized that the site of the neurilemmal-glial junction (medial or lateral) has an effect here. If the U.S. criteria for the treatment of a patient by an audiologist are applied to this series of patients, then 7 patients (1.5%) would not have had the diagnosis of vestibular schwannoma. If the U.K. criteria are applied, this number of missed tumors is 17 (3.6%). The addition of unilateral tinnitus as an indicator of the need for otologic investigation reduced the number of patients who might be missed to 2 (0.42%) for the U.S. cases and 5 (1.1%) for the U.K. cases., Conclusions: Of patients with vestibular schwannoma, 10.7% have an atypical principal presenting symptom, and this group of patients has significantly larger tumors than those patients who present typically. This finding is of particular relevance to the entry point of such cases to the healthcare system. A number of patients with vestibular schwannoma appear to pass the criteria for treatment by an audiologist without reference to an otologic opinion. These patients may not be investigated from an early stage with potential implications for increased morbidity.

Objective: The aim of this study was to identify distinguishing characteristics of uncommon lesions of the cerebellopontine angle (CPA) and internal auditory canal (IAC) in order to attain the correct diagnosis and thus formulate an appropriate therapeutic protocol., Study Design: A retrospective chart analysis was performed on all patients with surgically managed lesions of the IAC and CPA referred to neuropathology from January 1985 to April 1996., Setting: All patients were treated by New York University faculty at a tertiary referral center., Patients: Among 426 surgical cases identified, 384 patients (90.1%) with acoustic neuromas and 18 patients (4.2%) with meningiomas were excluded. The remaining 24 cases, involving 17 women and seven men with a median age of 34 years, were analyzed., Intervention: Most patients underwent audiovestibular evaluations, as well as magnetic resonance imaging (MRI) and computed tomographic (CT) scanning, and all patients underwent neurotologic surgery as part of their management protocol., Main Outcome Measures: Correlating patient presentation, preoperative imaging, and surgical findings often identified distinguishing characteristics of unusual CPA and IAC lesions., Results: Unusual lesions identified at the CPA and IAC included: four epidermoids, four lipomas, two facial neuromas, two arachnoid cysts, two choroid plexus papillomas, two metastatic adenocarcinomas, one metastatic neuroblastoma, one ependymoma, one lymphoma, one cholesterol cyst, one angioleiomyoma, one venous hemangioma, one cavernous angioma, and one pontine glioma., Conclusions: Preoperative tumor differentiation based on the patient history, physical examination, audiovestibular testing, CT, and MRI help the surgeon to formulate an appropriate treatment protocol.

Objective: Ongoing controversy regarding the optimal treatment of acoustic neuromas in the elderly population has prompted us to examine the our experience in order to arrive at a treatment algorithm., Study Design: Retrospective case review., Setting: Tertiary referral center., Patients: The records of 48 elderly patients ranging from age 70 to 90 years with acoustic tumors were reviewed., Interventions: In 34 cases, tumor size was followed through serial imaging for a mean 28.5 months (range 5-108 months). Eight of these patients subsequently required surgery for significant tumor growth. An additional 12 patients were managed surgically from the time of diagnosis., Main Outcome Measure: The natural history of acoustic neuromas in the elderly population., Results: The mean tumor growth rate for the watched group was 0.29 cm/y. Fifteen patients demonstrated no growth whereas accelerated growth was noted in eight cases. Ten patients with tumors confined to the internal auditory canal demonstrated an average growth rate of only 0.06 cm/y over a mean interval of 38 months. For the surgically treated group, the mean tumor size at the time of resection was 2.8 cm. Resection was described as complete in 17 cases and near-total in three cases. Perioperative complication rates and facial nerve results were comparable to our figures for all age groups. There was one perioperative death., Conclusions: Elderly patients with small acoustic neuromas should be offered a trial of observation. When significant tumor growth, size, or neurologic deterioration are demonstrated, early surgical intervention is required to avoid complications associated with the removal of larger tumors.

To characterize otologic causes for vertigo, data on 564 patients with the six most common diseases involving vertigo were retrieved from the database of a computer-aided diagnostic system for neurotologic diseases. The diseases were Meniere's disease, vestibular schwannoma, benign paroxysmal positional vertigo, vestibular neuritis, sudden deafness, and traumatic vertigo. The prevalence of tinnitus in the study population was 76%. The most severe forms of vertigo and nausea were found in vestibular neuritis, whereas the most severe case of tinnitus appeared in Meniere's disease. Of the patients with vestibular schwannoma, 49% had had vertigo. A linear discrimination analysis using case history classified 90% of the patients into correct groups. The key questions discriminating between the diseases concerned the frequency and duration of vertigo attacks, the duration of hearing loss and vertigo, and the occurrence of head injury. Making a correct diagnosis during the first office visit can be difficult, especially for sudden deafness, vestibular schwannoma, and Meniere's disease. Neurotologic and audiometric information was of minor value in distinguishing between these six diseases. Vestibular schwannoma had significantly greater asymmetry in electronystagmography and smaller gains in smooth pursuit in comparison with the other disease. Factorial analysis did not aid the clustering of these diseases.

High-resolution computed tomography (HRCT) is the standard imaging technique used in cochlear implantation. However, cochlear and retrocochlear soft-tissue abnormalities may not be detected with HRCT alone. To determine whether magnetic resonance imaging (MRI) provides clinically significant information in addition to HRCT in the evaluation of candidates for cochlear implants, we performed a prospective study of 13 consecutive patients with cochlear implant patients receiving preoperative, high-resolution fast spin-echo T2-weighted MRI scans of the temporal bone. MRI identified unanticipated cochlear fibrosis in one patient, vestibular schwannoma in one patient, patency in the second turn of the cochlea in a patient with labyrinthitis ossificans, and disproved cochlear fibrosis suspected on HRCT imaging in one patient. These findings were significant for clinical decisions regarding candidacy for surgery, side selection for surgery, and surgical technique in cochlear implantation. Our experience suggests a high-resolution T2-weighted MRI of the temporal bone should be used preoperatively in addition to HRCT before cochlear implantation.

Osteomas of the temporal bone are benign neoplasms that may be encountered by otolaryngologists. Clinically they should be distinguished from exostoses, which involve the external auditory meatus and are a well recognized entity. Osteomas involving the middle ear and ossicles are extremely rare. There is only one case report in the literature of an osteoma involving an ossicle and in that patient, who presented with conductive loss, the incus was involved. The present report presents a 48-year-old white male, who on routine examination was found to have a mass in his left tympanic membrane. Under local anesthesia the mass was totally excised, after it had been separated from the umbo. Histopathologic sections of the mass revealed a benign osteoma. A brief review of osteomas and exostoses of the temporal bone is presented.

Identification of small acoustic neuromas has become commonplace. Frequently, affected individuals are identified prior to the development of significant hearing loss. Whereas many studies have focused on hearing preservation surgery, few have reported on stability of hearing results after resection of acoustic neuroma. Between 1985 and 1991, 36 patients underwent resection of an acoustic neuroma via a retrosigmoid, internal auditory canal approach with attempted hearing preservation. Hearing was preserved in 24 patients; 17 were available for testing for the present study. Follow-up ranged from 1.5 to 8 years. All patients underwent complete audiologic assessment; most patients also underwent auditory brainstem response testing. There was an average 6 dB increase in pure-tone average between early (1 month) postoperative and long-term postoperative test results. A binomial single subject statistic was used to assess for significant changes in speech recognition scores over time. In two subjects there was a significant decrease; however, speech recognition also improved significantly in two subjects. Five of the 17 subjects demonstrated either a significant (at least 15 dB) increase in pure-tone average or a significant decrease in speech recognition over the time-course of the study. All patients maintained usable hearing. We conclude that long-term hearing preservation is a realistic goal in selected acoustic neuroma operations.

Odontoma of the middle ear cleft is an unusual cause of conductive hearing loss. We report two cases and discuss the developmental mechanism by which this anomaly may occur. The differential diagnosis of calcified masses in the middle ear is also discussed.

A case report of a 39-year-old man suffering from left-sided, progressive hearing loss is presented. As well, the patient noted ipsilateral recurrent facial paralysis. MRI succeeded in confirming the presence of a tumor in the internal acoustic canal 18 months after the first MRI.

In the case presented, an intralabyrinthine schwannoma was discovered during translabyrinthine eighth nerve section. Analysis of this case and the 22 previously reported cases of intralabyrinthine schwannoma highlights the difficulty in preoperative diagnosis of this lesion. Concerns are raised about the frequency with which this diagnosis may be missed and its implication in neurotologic surgery for vertigo.

Preservation of facial nerve function during acoustic tumor resection is an important goal. Patients with acoustic tumors who present with facial weakness may be at increased risk of postoperative facial paralysis. Subclinical tumor involvement of the facial nerve may be more frequent than is commonly recognized. A preliminary study was undertaken to assess the incidence of subclinical involvement of the facial nerve and to discern if such involvement had prognostic implications. Preoperative facial electroneurography (ENoG) was performed in thirteen patients undergoing surgical resection of acoustic tumors. Three of thirteen patients demonstrated preoperative facial weakness and ENoG was abnormal in all three of these patients. Of the ten patients with normal facial function preoperatively, eight revealed amplitude reduction on ENoG testing. Further study is required to discern the prognostic value of preoperative ENoG abnormalities.

The coexistence of an acoustic neuroma with otosclerosis can prove to be a great diagnostic dilemma. In such cases, the diagnosis of acoustic neuroma is usually delayed while more common causes of sensorineural hearing loss associated with otosclerosis or its surgery are considered. Any asymmetric progression of a sensorineural loss or shift in discrimination after stapes surgery, whether sudden or gradual, should provoke suspicion of a second pathologic process. These include perilymph fistula, labyrinthine otosclerosis or ischemia, and acoustic neuroma. The use of auditory brainstem response and acoustic reflex testing and various imaging techniques is essential for accurate diagnosis. This paper includes two cases that demonstrate this dual pathology, bringing the total to 15 such cases reported in the literature. The purposes of this paper are to alert the clinician to the diagnostic problem of acoustic neuroma coexisting with otosclerosis and to propose a means of evaluating these patients.