Outcome of translabyrinthine surgery for vestibular schwannoma in neurofibromatosis type 2.

OBJECTIVES: To analyse the long-term outcome of translabyrinthine surgery for vestibular schwannoma (VS) in neurofibromatosis type 2 (NF2). RESEARCH TYPE: Retrospective cohort study. SETTING: Two tertiary referral NF2 units. PATIENTS: One hundred and forty eight translabyrinthine operations for patients with VS were performed. Preoperative stereotactic radiotherapy had been performed on 12(9.4%) patients. RESULTS: Mean tumour size was 3.1 cm. Total tumour excision was achieved in 66% of cases, capsular remnants were left in 24% of cases, and subtotal excision was achieved in 5% and partial removal was achieved in 5%. The radiological residual/recurrence rate was 13.9%. The perioperative mortality was 1.6%. At 2 years postoperatively, facial function was expressed in terms of House-Brackmann score (HB): HB 1 in 53.4%, HB 1/2 in 61.3%, HB 1-3 in 83.2% and HB 4-6 in 16.8%. All nine patients who underwent surgery following failed stereotactic radiotherapy had HB 3 function or better. Among 9.5% of the cases, 14 facial nerves were lost during surgery and repaired using direct anastomosis or grafting. There was no tinnitus present preoperatively in 27% of the cases, and 22% of patients developed tinnitus postoperatively. In patients with preoperative tinnitus, 61% remained the same, 17% got it resolved and only in 21% it worsened. The preoperative hydrocephalus rate was 26%, and among 15% of the cases five ventriculo-peritoneal (VP) shunts were performed. The cerebrospinal fluid leak rate was 2.5%. Fifty-six patients underwent auditory brainstem implantation (ABI) and two patients had cochlear implant (CI) sleepers inserted. CONCLUSIONS: The management of patients with NF2 presents the clinician with a formidable challenge with many patients still presenting themselves late with the neurological compromise and a large tumour load. There is still an argument for the management by observation until the neurological compromise dictates interventional treatment particularly with the option of hearing rehabilitation with ABI or CI. The translabyrinthine approach provides a very satisfactory means of reducing the overall tumour volume.

Outcome following retrosigmoid microvascular decompression of the facial nerve for hemifacial spasm.

This paper evaluates the outcome of retrosigmoid microvascular decompression of the facial nerve in a series of patients suffering from hemifacial spasm who had been referred to the skull-base team (comprising senior authors DAM and DGH). The paper is a retrospective review of 15 patients who underwent retrosigmoid microvascular decompression of the facial nerve at Addenbrooke's Hospital between 1985 and 1995. In this series it was possible to obtain complete resolution of hemifacial spasm in 93.3 per cent of cases in the short term and in 80 per cent in the long term. Twelve patients (80 per cent) were symptom-free post-operatively. Two patients had minor recurrence of symptoms occurring within six months of the procedure. One patient with no identifiable vascular impingement of the facial nerve had no improvement following surgery. Three patients suffered sensorineural hearing loss. Two patients complained of post-operative tinnitus, and transient facial palsy was noted in one patient. Retrosigmoid microvascular decompression of the facial nerve provides excellent long-term symptom control in a high percentage of patients with hemifacial spasm.

Bilateral optic nerve sheath meningiomas in a patient with neurofibromatosis type 2.

A 34-year-old woman who presented with hearing loss and tinnitus was found to have reduced vision bilaterally. Computed tomography scan revealed bilateral acoustic neuromas and bilateral optic nerve sheath meningiomas. The presence of bilateral acoustic neuromas fulfils the criteria for the diagnosis of central neurofibromatosis (neurofibromatosis type 2). Although this is the first report of bilateral optic nerve sheath meningioma in neurofibromatosis type 2, meningiomas are commoner in this dominantly inherited disorder, than in its absence and both forms of central nervous system tumour may be caused by loss of tumour suppressor genes on chromosome 22.

Surgery for acoustic neurinoma. An analysis of 100 translabyrinthine operations.

A consecutive series of 100 translabyrinthine operations for removal of acoustic neurinoma is reported. Complete tumor removal was achieved in 97% of cases. There were three perioperative deaths, and the postoperative morbidity rate was low. The facial nerve was preserved anatomically in 82% of patients. Preoperative facial weakness and tumor size larger than 2.5 cm were predictive of poor facial recovery. In patients with an intact nerve but complete facial palsy 1 week after surgery, electroneuronography was a good predictor of the final facial outcome and may influence the timing of rehabilitative procedures. With the exception of patients who have small tumors and good speech discrimination (where a suboccipital approach may preserve hearing acuity), the translabyrinthine operation is the procedure of choice for removal of acoustic neurinomas in patients who have normal hearing in the contralateral ear.

Molecular genetic investigation of the neurofibromatosis type 2 tumor suppressor gene in sporadic meningioma.

The authors investigated the role of somatic mutations of the neurofibromatosis type 2 (NF2) gene in sporadic meningioma. Neurofibromatosis 2 is a dominantly inherited familial tumor syndrome predisposing affected patients to a variety of central nervous system tumors including vestibular schwannoma and meningioma. Neurofibromatosis type 2 is caused by germline mutations in the NF2 tumor suppressor gene. In addition, the authors and others have reported that somatic NF2 gene mutations occur frequently in nonfamilial vestibular schwannoma. In this study, molecular genetic analysis was performed on 23 nonfamilial meningiomas. Paired DNA samples extracted from the blood and tumors of the patients were analyzed for loss of heterozygosity (LOH) in the region of the NF2 gene on chromosome 22 using closely linked DNA markers. The NF2 gene mutations were sought by single-stranded conformation polymorphism analysis and DNA sequencing. Fourteen (61%) of 23 meningiomas showed LOH in the region of the NF2 gene on chromosome 22. Somatic NF2 gene mutations were detected in eight meningiomas (35%) after screening all 17 exons. All tumors with NF2 gene mutations showed simultaneous chromosome 22 LOH. Review of the histopathological findings of the cases studied did not demonstrate any predominance of genetic abnormalities in a particular histological type of meningioma. These results are compatible with the hypothesis that the NF2 gene acts as a tumor suppressor and that its inactivation is important in the pathogenesis of sporadic meningioma.

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

OBJECTIVE: To quantify the postoperative quality of life in patients following surgical treatment for vestibular schwannoma. STUDY DESIGN: Patient self-assessment using the short form 36 (SF36) multidimensional quality of life health questionnaire. Sex- and age-matched normalized scores were calculated using a standardized process and accepted normative data. SETTING: Tertiary referral skull base unit. RESULTS: An 80% response rate (90 patients) was achieved. The postoperative quality of life in vestibular schwannoma patients, as quantified by seven of the eight SF36 health scales was less than the appropriate matched healthy standard. Comparison of a variety of preoperative patients and tumor factors-different operative approaches (translabyrinthine and retrosigmoid), tumor size (group cut of points of tumor diameter 1.5 mm and 2.5 mm), patient sex, and ranking of patient age-showed no statistically significant difference in measured quality of life outcomes for each of these traditional predictors. CONCLUSION: Reduced quality of life in patients after surgical treatment for vestibular schwannoma, coupled with the low tumor growth rates and minimal preoperative symptoms, supports a conservative approach to patient management. The advantages and disadvantages of a variety of approaches used to measure the quality of life after surgical treatment of vestibular schwannoma and their impact on clinical decision making for patients, are discussed.

Petrous apex cholesteatoma: diagnostic and treatment dilemmas.

The diagnosis and treatment of petrous apex cholesteatoma is a difficult surgical challenge. This study is a review of 14 cases of cholesteatoma involving the petrous apex. These cholesteatomas originated as a congenital primary lesion or secondary to an acquired lesion. The cases were evaluated according to the clinical features, the intraoperative findings, the radiological findings, and the surgical approaches. In this series, 83% of the patients presented with hearing loss and 50% presented with facial nerve weakness or paralysis (House grade II to VI). Intraoperative and radiological features revealed frequent direct labyrinthine and supralabyrinthine cell spread. The transpetrous surgical approach was used in all cases. The main factors affecting the surgical approach to be adopted are the inaccessible nature of the petrous apex, the extent of disease, the degree of facial nerve function, and the need for the prevention of cerebrospinal fluid leaks and the recurrence of the lesion.

Nervus intermedius function after vestibular schwannoma removal: clinical features and pathophysiological mechanisms.

The results of facial nerve outcome following vestibular schwannoma removal have generally ignored the sensory component of the nerve. This lack of reporting occurs partly because the distress relating to these functions is less obvious to the surgeon, and partly because the facial nerve grading systems currently used do not include the functions of the nervus intermedius. We have estimated the frequency and nature of abnormalities of nervus intermedius function following vestibular schwannoma removal using a retrospective questionnaire. Questionnaires were mailed to 257 patients and correctly completed and returned by 224 (87%) of the patients. Prior to surgery 5 (2%) of the patients complained of crocodile tears, 9 (4%) noted dryness of the eye, and 15 (6%) complained of an abnormality of taste. Postoperative crocodile tears occurred in 98 (44%), an absence or significant reduction in the production of tears was noted in 162 (72%), and a taste abnormality, either a significant reduction or an alteration in character, was noted in 107 (48%). The onset of crocodile tears approximated to a bimodal distribution, and the recovery of nervus intermedius functions was variable. This study has demonstrated that nervus intermedius abnormalities are common following vestibular schwannoma removal. It also documents their natural history and discusses the underlying pathophysiological mechanisms. We suggest that appropriate preoperative counseling be given to all patients undergoing surgery and that the functions of the nervus intermedius be included in the surgical reporting of facial nerve results in cerebellopontine angle surgery.

Molecular genetic analysis of the mechanism of tumorigenesis in acoustic neuroma.

OBJECTIVE: Acoustic neuroma, both familial and sporadic, is clinically and biologically a heterogeneous condition with a wide variation in age of presentation, length of history, and tumor growth rate. In an attempt to correlate this clinical diversity with the underlying molecular pathology, we have analyzed 43 paired blood-tumor DNA samples from patients with acoustic neuromas. DESIGN: Molecular genetic analysis. SETTING: Molecular genetic research laboratory. PATIENTS: Paired blood-tumor DNA samples were obtained from 43 patients (41 sporadic and two patients with neurofibromatosis type 2). MAIN OUTCOME MEASURES: Loss of constitutional heterozygosity was looked for in the region of tumor suppressor genes on chromosomes 3p, 5q, 11p, 17p, 17q, and 22. RESULTS: We found loss of heterozygosity exclusively for markers on chromosome 22. Thirty-nine percent of tumors showed allele loss, and in each case the loss of heterozygosity included the region of the neurofibromatosis type 2 (NF2) gene. No loss of heterozygosity was detected in the region of known or putative suppressor genes in chromosomes 3p, 5q, 11p, 17p, and 17q. CONCLUSIONS: This study has demonstrated that (1) chromosome 22 allele loss is a frequent event in sporadic acoustic neuroma; (2) the minimal region of loss of heterozygosity in acoustic neuroma includes the NF2 gene; (3) the known tumor suppressor genes investigated (VHL, adenomatous polyposis coli, WT2, p53, and NF1) do not appear to be important in the pathogenesis of acoustic neuroma; and (4) patients with extensive chromosome 22 loss tended to be younger and with a slightly shorter clinical history than those with no detectable allele loss.

Rare tumours of the cerebellopontine angle.

The vast majority of cerebellopontine angle (CPA) tumours are acoustic neuromas. However, in our series of 305 CPA tumours, one in five was another pathological lesion. Of the non-acoustic tumours, the majority were meningiomas, primary cholesteatomas and glomus jugulare tumours. A variety of rarely seen but fascinating pathologies were also treated. A study of these non-acoustic tumours has been carried out, looking at their relative incidence, histology and clinical features, as well as the radiological features that make them unusual and help to distinguish them from acoustic neuromas (vestibular schwannomas). The otoneurosurgical procedures required to excise these intriguing lesions are also discussed.

Extended temporal bone resection for squamous cell carcinoma.

OBJECTIVE: The aim of this study was to assess the surgical results of a series of patients from this unit who underwent extended temporal bone resection for recurrent squamous cell carcinoma as a salvage procedure. DESIGN: The surgical records of 15 patients were analyzed in detail. Each patient had salvage surgery in the form of an extended temporal bone resection with supraomohyoid block dissection, dural grafting, and free microvascular forearm or scalp rotation flap repair for recurrent squamous cell carcinoma in a radical mastoid cavity. RESULTS: Radical surgery yielded a 47% 5-year survival. Twenty-nine percent of the survivors had temporal lobe involvement that necessitated a partial excision of the temporal lobe of the brain. Histologic evidence of local lymph node involvement in the supraomohyoid neck dissection was present in 13% of cases. Those who died did so in the first postoperative year. All those with poorly differentiated tumors died. The survivors had well or moderately differentiated tumors. CONCLUSIONS: Radiotherapy alone or partial temporal bone resection, most commonly a radical mastoidectomy with or without preoperative or postoperative radiotherapy is used by the majority of otolaryngologists in treating squamous cell carcinoma of the temporal bone. The 5-year survival rate after this treatment remains depressingly low and the prognosis gloomy, particularly for advanced tumors. The findings in this series of extended temporal bone resections as salvage surgery in recurrent disease is encouraging, and radical surgery combined with radiotherapy from the outset may give much better 5-year survival figures in the future than the conventional partial temporal bone resection and radiotherapy.

Does choice of hearing selection criterion and reporting criteria affect the hearing preservation rate in vestibular schwannoma surgery?

With increasing refinement in the surgery of vestibular schwannoma the aims of complete tumor removal and facial nerve preservation have been largely fulfilled. However, the reputation of and place for hearing-preservation surgery still remain uncertain. A major part of this uncertainty is the result of difficulties in interpretation of the various reported results of hearing-preservation surgery. Meaningful comparison between series is difficult because of the varied number of postoperative reporting criteria commonly in use today. Although it is acknowledged that the postoperative reporting criteria affect the hearing-preservation rates, what is not readily appreciated is that preoperative selection criteria for hearing-preservation cases can also significantly affect the success rate of hearing-preservation acoustic neuroma surgery. This article models the many possible outcomes of hearing-preservation schwannoma surgery by use of the previously reported Cambridge series as an illustrative example. With these models some understanding can be gained of the effect of choosing various preoperative and postoperative hearing criteria on the overall hearing-preservation success rate.

Hearing preservation in solitary vestibular schwannoma surgery using the retrosigmoid approach.

The results of 50 cases of vestibular schwannoma surgery with hearing preservation performed by the retrosigmoid approach at Addenbrooke's Hospital, Cambridge, during a 10-year period are presented. The hearing-preservation rate, using audiometric criteria set by others as "serviceable hearing" (Wade PJ, House W. Otolaryngol Head Neck Surg 1984;92:1184-93; Silverstein H, et al. Otolaryngol Head Neck Surg 1986;95:285-91; Cohen NL, et al. Am J Otol 1993;14:423-33) was 8% (4 of 50 cases). When the more stringent selection criteria of near-normal hearing and reporting criteria of socially useful hearing preservation (pure-tone average < 30 dB/speech discrimination score > 70%) is used, the hearing-preservation rate is 4.8% (1 of 21 cases). The only preoperative factor that may predict a favorable hearing-preservation outcome is normal auditory brain stem response morphology (Fisher's exact 2-tailed test, P < 0.001). The number of suitable candidates for hearing-preservation surgery are few. Reasonable indications for attempted vestibular schwannoma surgery with hearing preservation are discussed.

Bilateral electrocochleographic findings in unilateral Menière's disease.

At present, electrocochleography is the only proven investigation that can demonstrate objectively the presence of endolymphatic hydrops. The electrophysiologic recordings in response to sound stimuli show an enhancement of the negative summating potential in these cases. It is well established that patients with unilateral Meniere's disease have a high likelihood of development of the disease bilaterally in the fullness of time. Using transtympanic electrocochleography in 40 patients who manifested unilateral clinical Meniere's disease, we have recorded bilateral abnormalities indicative of endolymphatic hydrops in 35% of cases. The early recognition of incipient Meniere's disease in the asymptomatic contralateral ear of a patient with known unilateral disease has obvious profound implications for patient management.

A molecular, clinical, and immunohistochemical study of vestibular schwannoma.

The molecular pathogenesis of vestibular schwannoma has been investigated by determining the extent of chromosome 22 loss of heterozygosity in 77 tumors and relating these findings to clinical and immunohistochemical indexes of tumor behavior. Loss of heterozygosity was looked for at eight chromosome 22q loci. Clinical details were obtained in all 77 cases, and a clinical growth index was calculated for each tumor. The proliferative index was estimated in all tumors by using a monoclonal antibody to the proliferating cell nuclear antigen and by calculating the labeling index. Forty percent (31 of 77) of the tumors showed allele loss, and in each case this loss involved the region of the neurofibromatosis type 2 gene. No evidence was found that the presence of chromosome 22 allele loss was associated with the clinical growth index. On the log scale, however, an association was seen between the clinical growth index and the proliferating cell nuclear antigen labeling index p = 0.001). These results suggest that chromsome 22 allele loss is a frequent event in vestibular schwannoma. Tumor behavior, however, appears to be independent of the chromosome 22 mutation. It is proposed that chromosome 22 allele loss and neurofibromatosis type 2 gene inactivation is an early event, possibly involved in the initiation of tumorigenesis in vestibular schwannoma. Tumor growth appears to be independent of this mutation and is likely to be determined by other as yet undefined factors.

Transtympanic electrocochleography in patients with syphilis and hearing loss.

Transtympanic electrocochleography was carried out on 18 syphilitic patients (30 ears were tested) most of whom were suffering from the late onset congenital form of the disease. A diphasic action potential with a large negative summating potential on the descending limb was found in 77.7% of ears; the cochlear microphonic potential was always of small amplitude. While these findings are not pathognomonic of syphilis, they are characteristic and may be explained on pathological grounds.

Clinical usefulness of electrocochleography in Meniere's disease: an analysis of dehydrating agents.

Both electrocochleography and glycerol dehydration have an important diagnostic and prognostic role in the management of patients with endolymphatic hydrops, whether idiopathic as in Meniere's disease or secondary to certain diseases of the otic capsule. Abnormal electrocochleographic responses in a "normal" ear can be used to predict when Meniere's disease will become bilateral. There is a significant correlation between the effects of glycerol and of endolymphatic sac surgery on the pars inferior, at least over the span of several years. The subject hearing gains, the objective improvements in electrocochleographic responses, and the objective evidence of diminished inner ear impedance, all following proven glycerol dehydration, indicate that even in fairly advanced Meniere's disease, but especially in the earlier stages, reversibility is possible. This is a tantalizing therapeutic challenge.

Transtympanic electrocochleography during glycerol dehydration.

Thirteen patients with Meniere's disorder were tested using transtympanic electrocochleography during glycerol dehydration. The most common finding was a decrease in the negative summating potential and this appeared to be a more sensitive indicator of changes occurring in the cochlea than pure tone audiometry and speech discrimination. A pathophysiological explanation for this observation is offered and the possibility of using this decrease in the negative summating potential as a pointer to the prognosis of endolymphatic sac surgery is discussed.

Reduction in junior doctors' hours in an otolaryngology unit: effects on the 'out of hours' working patterns of all grades.

This study aimed to assess the effects of recent controls on juniors' duty hours (the 'New Deal') on the work performed by all grades of ENT medical staff 'out of hours'. For 100 days in 1993 the out of hours duties of all grades of doctor in the Otolaryngology Unit were monitored using daily logs. Three patterns of cover were run in parallel and subjected to comparison: Light: Senior House Officer (SHO)--Consultant (CON); Traditional: SHO-Intermediate (Registrar or Senior Registrar)--Consultant; Cross-cover--Pre-Registration House Officer (PRHO)--Intermediate-Consultant. The SHO 'out of hours' daily workload did not differ significantly between the traditional and light systems (median hours: 5.6 versus 5.0). There was an increase in working hours for the intermediate (registrar or senior registrar) grade of 84 per cent when the cross-cover system was in operation compared with the traditional system (median hours: 5.0 versus 2.8; p < 0.0001--Mann-Whitney U test). Consultant working hours increased by an average of 132 per cent as a result of removal of the intermediate tier (median hours: 1.7 versus 0.80; p < 0.0001). Reduction in on-call hours of junior staff resulted in a need for cross-cover and also in the frequent removal of an intermediate tier of staff. This has been shown to have a considerable effect on working patterns for intermediate and senior grades in an ENT unit of average size. Further reductions would be expected to have major effects on the working patterns of the consultant grade and considerably dilute the emergency experience of trainees.

Effective anaesthesia for transtympanic electrocochleography.

The objective of this study was to quantify the anaesthetic effect of EMLA cream during transtympanic electrocochleography (TTECochG) and thereby to determine if the application of EMLA should be recommended in routine practice of electrocochleography (ECochG). ECochG provides useful information in patients with inner ear fluid disorders. A major concern regarding transtympanic positioning of the electrode in ECochG is patient discomfort. Previous work has suggested that EMLA cream may make this technique more tolerable to patients. A prospective randomized study was performed evaluating the discomfort associated with unilateral TTECochG in a group where EMLA cream was used to anaesthesize the tympanic membrane (n = 24), and in a group where no anaesthesia was used (n = 22). A statistically significant difference was evident between the discomfort ratings of the groups (P < 0.0001, Mann-Whitney U test), the discomfort being greater in the no anaesthesia group. EMLA cream has thus been shown to alleviate the level of discomfort associated with TTECochG and so to be an acceptable modification of this technique.