Mitigating noise-induced hearing loss after blast injury

Introduction

Whilst hearing injuries are not life threatening they may have a profound impact on the victim’s ability to understand and interact with the world around them. Noise-induced hearing loss is a common occupational injury and hearing impairment as a consequence of noise and blast exposure remains the most common injury in both war and peace for military personnel. Health and Safety legislation has made an impact and in the future innovative approaches to mitigate against acoustic injury sustained in the work place will be fundamental. For the Armed Forces, noise exposure during conflict is unpredictable. Furthermore, recent events in the UK and elsewhere have highlighted the potential civilian impact of blast injuries on hearing in the acute setting. No well-established protocol for the management of acute, blast-induced hearing injury currently exists.

Methods

Narrative review is supported by electronic literature searches of PubMed, Embase and the Cochrane Library. Synthesis of published literature and production of flow charts for the acute setting are part of the Emergency Preparedness, Resilience and Response programme.

Results

Whilst there is a lack of high-quality randomised controlled trials, there are a number of studies that may inform our choice of acute management. Animal studies of acute acoustic trauma have shown the potential protective effects of corticosteroids. Human data may be extrapolated from sudden onset sensorineural hearing loss where again there is evidence for the use of corticosteroids. Less certainty exists around the use of other treatments including antioxidants. Intratympanic administration of corticosteroids may be superior to oral administration, particularly in the salvage setting. No evidence exists specifically pertaining to the paediatric population.

Conclusion

Prompt identification of any hearing deficit followed by administration of glucocorticoids either orally or via intratympanic preparations is the mainstay of management. Further research is needed to identify the optimum acute management.

Curtailment of Higher Surgical Training in the UK: Likely Effects in Otology

Higher surgical training in the UK faces a cut of two years. We conducted a questionnaire survey to assess the operative experience of current higher surgical trainees in otological surgery and the likely effect of the proposed reduction from six to four years.

91 (65%) of the 142 higher surgical trainees responded with details of major otological procedures performed (independently or assisting) over one year. In the present six-year scheme a typical trainee performs 72 myringoplasties, 79 mastoidectomies, 7 skull base procedures and 28 other procedures. In the first four years, however, his or her experience is only 39 myringoplasties, 44 mastoidectomies, 4 skull base procedures and 7 others.

The large shortfall in experience that might result from shortening of the training programme would need to be met by intensification of the training or institution of accredited otology fellowships. Very similar dilemmas are faced by other surgical specialties.

The bone-anchored hearing aid in the rehabilitation of single-sided deafness: experience with 58 patients

OBJECTIVES

To assess the efficacy of the bone-anchored hearing aid (BAHA) in the rehabilitation of single-sided deafness (SSD).

STUDY DESIGN

Retrospective case-control series review.

SETTING

Tertiary referral unit.

PATIENTS

Fifty-eight consecutive patients that had a bone-anchored hearing aid for single-sided deafness completed outcome questionnaires, building upon earlier audiological assessment of 19 patients. Single-sided deafness controls (n = 49) were mainly acoustic neuroma patients.

MAIN OUTCOME MEASUREMENTS

speech discrimination testing in directional noise, speech and spatial qualities of hearing questionnaire and the Glasgow Benefit Inventory (GBI).

RESULTS

The mean follow-up time was 28.4 months. Five (13%) of the bone-anchored hearing aid patients were non-users because of lack of benefit. The audiometric testing confirmed that when noise was on the bone-anchored hearing aid side speech perception was reduced but benefited when noise was on the side of the hearing ear. There was no difference between the Speech and Spatial Qualities of Hearing Scores in bone-anchored hearing aid users and controls. In particular there was no difference in the spatial subscores. In the bone-anchored hearing aid users the median Glasgow Benefit Inventory score was 11. If the non-users are included then 13 (22%) patients had no or detrimental (negative) Benefit scores. No or negative benefit scores were more frequent in those deaf for <10 years. In open-field questions, patients felt the bone-anchored hearing aid was most useful in small groups or in 'one-to-one' conversation.

CONCLUSIONS

Bone-anchored hearing aid rehabilitation for single-sided deafness is less successful than for other indications, reflected here by relatively low median Glasgow Benefit Inventory scores. There was also no significant difference between controls and bone-anchored hearing aid users in the Speech and Spatial Qualities of Hearing Questionnaire. Patients with a longer duration of deafness report greater subjective benefit than those more recently deafened, perhaps due to differing expectations.

Conservative versus primary surgical treatment of acoustic neuromas: a comparison of rates of facial nerve and hearing preservation

OBJECTIVES

To determine whether patients with small to medium sized acoustic neuromas managed conservatively suffer reduced rates of facial nerve and hearing preservation when compared with patients undergoing primary surgery.

DESIGN

An intention-to-treat comparison between patients managed conservatively at first presentation and those managed with primary surgery.

SETTING

Tertiary referral neurotological centre in Birmingham, UK.

PARTICIPANTS

Data were drawn from our database of 487 sporadic acoustic neuromas managed from 1997 to present day.

MAIN OUTCOME MEASURES

Facial nerve status (assessed using the House-Brackmann system) was collated for all conservatively managed patients (n = 167) and compared with that expected when calculated from primarily surgically managed tumours of equivalent size (n = 121). A chi-square test was employed to test the statistical significance of any difference. Hearing preservation (maintenance of AAO-HNS Class) in patients presenting with Class A or B hearing was compared between conservatively managed patients and those with primary surgical management.

RESULTS

Observed facial nerve preservation in conservatively managed patients was significantly better (P < 0.001) than expected when calculated from rates of facial nerve preservation in surgically managed patients. Hearing preservation was also significantly more successful in conservatively managed patients (Pearson chi-square: P < 0.000).

CONCLUSIONS

An initial period of conservative management is a safe and reasonable management policy in all acoustic neuromas up to 2 cm in size at the cerebello-pontine angle. Given that there are no failsafe ways of deciding potential for growth in acoustic neuromas, initial conservative management of these tumours offers superior hearing and facial nerve preservation when compared with primary surgical treatment.

Parapharyngeal space tumour presenting as recurrent uvular oedema

Neoplasms of the parapharyngeal space are uncommon and usually present as an intra-oral or neck mass. They often elude early diagnosis due to their deep-seated nature. Here we report a case presenting with recurrent oedema of the uvula. The pathophysiology of this previously unreported mode of presentation is discussed.

Vestibular schwannomas with fluid–fluid level

Vestibular schwannomas containing cystic parts are common, but it is extremely rare for a vestibular schwannoma to contain fluid-fluid levels. In this report, we present two cases of vestibular schwannoma with magnetic resonance imaging findings of a fluid-fluid level, and we discuss the radiological features and possible mechanism of fluid-fluid level formation.

The genetics of paragangliomas: a review

Familial head and neck paragangliomas account for approximately 10% of all head and neck paragangliomas. There are three known genes associated with genetic susceptibility to head and neck paragangliomas: succinate dehydrogenase complex subunit 'D', 'B' and 'C' (SDHD, SDHB and SDHC). The genes most frequently implicated: SDHD and SDHB, also predispose to phaeochromocytoma. SDHD shows a complex inheritance pattern - tumours do not develop if the mutation is inherited from the mother. SDHB mutations are associated with malignant phaeochromocytoma. Patients who present with a family history of paraganglioma or phaeochromocytoma, with multiple tumours, or early onset tumours (<50 years), should be referred for genetic investigation.

Facial palsy secondary to cholesteatoma: analysis of outcome following surgery

Facial palsy is a rare presenting feature of cholesteatoma. Prompt treatment usually results in a good outcome, but if treatment is delayed the prognosis can be difficult to predict. We retrospectively reviewed 326 consecutive patients who had undergone temporal bone surgery for cholesteatoma. Eleven patients had presented with facial palsy, of whom eight had petrous apex involvement and three had disease confined to the middle-ear cleft. All patients with middle-ear disease were operated upon within two months of presentation, and all showed some recovery in facial function. The diagnosis had been delayed in all eight cases of apical disease, with four cases having had a long-standing total weakness. One case treated after seven months' partial weakness achieved a full recovery. In three cases of long-standing partial weakness, pre-operative facial function was preserved by maintaining the facial nerve in its normal anatomical location.

Facial palsy associated with cholesteatoma should be treated as early as possible. Recovery can occur even if treatment is delayed for up to seven months. After this time, recovery is increasingly unlikely, but any residual function can be maintained and further deterioration prevented.

The influence of the Internet on decision making in acoustic neuroma

Objective: To determine the access to and the use of the Internet by acoustic neuroma patients as a medical information source, and the influence of the Internet on decision-making, as well as the patients' views on the quality of particular sites.

Materials and methods: A retrospective 27-item questionnaire was sent to 138 consecutive acoustic neuroma patients diagnosed between 1997 and 2002. The study included patients treated by conservative, radiotherapeutic and surgical modalities.

Main outcome measures: Patient demographics, the extent of Internet use as well as quality and quantity of available information.

Results: There were 86.95 per cent questionnaires available for analysis. Twenty-four per cent accessed the Internet to obtain information about acoustic neuromas. Ninety-seven per cent of patients said that the information provided in the clinic matched with the information obtained from the websites, 49 per cent said that the information obtained from the Internet did not influence decision making regarding acceptance of treatment of their tumour. Some patients said the Internet information was depressing, devastating, and they would never look up the Internet again for medical information.

Conclusion: A significant proportion of our patients accessed the Internet for information. Caution should be exercised when advising patients regarding websites as the information on the Internet is often not controlled or checked for accuracy. Acoustic neuroma specialists and ENT surgeons in general should familiarize themselves with related websites so that patients can then be directed to high-quality sites.

Cerebellopontine angle arachnoid cysts in adult patients: what is the appropriate management?

Arachnoid cysts can occur at different intracranial sites, including the cerebellopontine angle (CPA). The incidence of arachnoid cysts is 1 per cent of all intracranial lesions. Recent advances in MRI (magnetic resonance imaging) scan techniques have led to CPA arachnoid cysts being more frequently diagnosed and with a higher degree of certainty. The need for further understanding of their natural history as well as for the development of a management rationale has been highlighted with this increased rate of diagnosis.

We present a series of five adult patients with different clinical presentations attributed to CPA arachnoid cysts. These lesions have a characteristic location in the posterior-inferior aspect of the CPA below the facial and vestibulocochlear nerves. These cysts did not show change in size on repeated MRI scan and the patients’ symptoms did not progress over the period of follow up. Our findings would support a conservative management approach to the majority of these cysts.

A large and uncharacteristically aggressive cholesterol granuloma of the middle ear

Cholesterol granulomas of the middle ear tend to be benign in nature, frequently seen by otologists during cholesteatoma or chronic otitis media surgery and easily dealt with by evacuation. In contrast, cholesterol granulomas of the petrous apex appear to have a more aggressive nature and present significant pathological threats. We present a case of a large destructive cholesterol granuloma of the middle ear eroding the middle and posterior cranial fossa bone and dura to exert a mass effect upon the temporal lobe. We emphasize the destructive potential of this extremely rare middle-ear cholesterol granuloma, and draw attention to the distinction between this variant and the commonplace and benign form of the lesion more usually found at this site. We also present the current theories of the aetiology of cholesterol granuloma formation with possible explanations for the rare aggressive behaviour.

An analysis of diagnostic delay in unilateral facial paralysis

Bell’s palsy or idiopathic facial palsy is the commonest cause of unilateral lower motor neuron facial palsy. Misdiagnosis of facial nerve palsy as Bell’s palsy is still seen in clinical practice. The clinician should always consider the possibility of a potentially serious underlying pathology before making the diagnosis of Bell’s palsy.

We present a series of 13 patients referred to our ENT department with an initial diagnosis of Bell’s palsy. Further clinical examination and investigation revealed the underlying cause. Many had additional symptoms and signs related to the ear.

In all patients with unilateral facial palsy a detailed history should be taken and thorough clinical examination carried out. Where no recovery occurs within the expected time period further radiological investigations such as computerized axial tomography (CT) and magnetic resonance imaging (MRI) should be performed. Current scanning techniques provide good quality images, which can show occult lesions of the temporal bone, internal acoustic canal and/or cerebellopontine angle. Radiologists with a special interest and experience in otoneurological radiology should ideally report these images, and a close co-operation between ENT surgeon and radiologist is essential in arriving at a proper diagnosis.

Dissemination of fat in CSF: a common finding following translabyrinthine acoustic neuroma surgery*

OBJECTIVES

Following translabyrinthine craniotomy the temporal bone defect is commonly obliterated using a free autologous fat graft. In this series the dura was put back in place but not closed primarily. As the fat graft remains in direct contact with the cerebro spinal fluid (CSF) there is potential for dispersal of fat within the CSF space. This paper aims to determine the frequency of such CSF fat dissemination and its clinical significance.

DESIGN

A retrospective review of translabyrinthine acoustic neuroma removal with free fat autograft obliteration of the temporal bone defect between the years 1997 and 2000.

SETTING

Tertiary referral oto-neurosurgical centre. Postoperative magnetic resonance (MR) imaging.

PARTICIPANTS

All translabyrinthine patients who had postoperative MR imaging were included. Twenty-six cases were identified. Age range was 13-70 years. Fourteen were male patients.

MAIN OUTCOME MEASURES

Evidence of CSF fat dissemination on MR and patients' clinical findings.

RESULTS

Twenty-two of the 26 scans (85%) demonstrated evidence of fat dissemination into the subarachnoid CSF spaces in the form of microemboli. The cerebellopontine angle was the most common site involved. No evidence of ventricular dilation or any other abnormality was noted. There was no relationship between the presence or extent of fat microembolization and the patients' clinical course.

CONCLUSIONS

This study suggests that free fat placed in temporal bone defects commonly migrate into the subarachnoid space and subsequently move around in these spaces. This is not associated with any complications such as hydrocephalus, meningitis or prolonged postoperative headache.

Curtailment of higher surgical training in the UK: likely effects in otology

Higher surgical training in the UK faces a cut of two years. We conducted a questionnaire survey to assess the operative experience of current higher surgical trainees in otological surgery and the likely effect of the proposed reduction from six to four years. 91 (65%) of the 142 higher surgical trainees responded with details of major otological procedures performed (independently or assisting) over one year. In the present six-year scheme a typical trainee performs 72 myringoplasties, 79 mastoidectomies, 7 skull base procedures and 28 other procedures. In the first four years, however, his or her experience is only 39 myringoplasties, 44 mastoidectomies, 4 skull base procedures and 7 others. The large shortfall in experience that might result from shortening of the training programme would need to be met by intensification of the training or institution of accredited otology fellowships. Very similar dilemmas are faced by other surgical specialties.

Anterior inferior cerebellar artery syndrome: fact or fiction

A prospective analysis of patients referred by Otolaryngologists from a tertiary hospital for detailed assessment of the posterior cranial fossa was undertaken. The objectives were to evaluate radiological characteristics of the anterior inferior cerebellar artery (AICA) within the cerebellopontine angle (CPA) and the internal auditory canal (IAC), and to correlate these characteristics with ipsilateral auditory symptoms. Three hundred and thirty-two consecutive adult patients who presented with unilateral auditory symptoms were studied. All patients were referred by the Department of Otolaryngology at City Hospital, Birmingham, from October 1999 to October 2001. Magnetic resonance imaging (MRI) with three-dimensional Fourier Transformation Constructive Interference in Steady State (3D FT-CISS) was the imaging strategy used to investigate each patient. Six hundred and sixty-four sides were studied and the AICA loop was identified in all patients. Using a simple anatomical classification to type the loops: there were 412 type I loops (within the CPA), 202 type II loops (at the porus acousticus, extending up to 50% of IAC) and 50 type III loops (extending beyond 50% of IAC). There was a statistically significant association with unilateral hearing loss and type II and III AICA loops (P = 0.016 and P = 0.006 respectively). An association between the presence of a large diameter vascular loop in the CPA and unilateral auditory symptoms was not found to be significant (P > 0.05).

Iatrogenic perforation in endoscopic stapling diverticulotomy for pharyngeal pouches

In pharyngeal pouch surgery, the relatively new technique of endoscopic stapling diverticulotomy has a number of advantages over more traditional surgical treatments, such as Dohlman's procedure and open pouch excision, and now seems to be the procedure of choice. However, a number of iatrogenic perforations and deaths have been reported with this procedure. We present three cases of iatrogenic perforations occurring during endoscopic stapling of a pharyngeal pouch by different surgeons in our unit, and review the management, causes and prevention of this potentially life-threatening complication.

Gunshot injuries to the temporal bone

The current incidence of missile injury to the temporal bone (MITB) is very low in the United Kingdom. However, the increasing frequency of firearm violence in Britain suggests a greater risk of occurrence. This, along with the devastating potential sequelae of MITB (facial palsy, dead ear, intracranial damage, major vascular injury and cosmetic disfigurement), requires otolaryngologists to be conversant with all aspects of their management. The risk of major complications is much higher with MITB than with temporal bone injury following blunt trauma, and surgical management is, therefore, much more common. We present one such case, and review the literature outlining the pathogenesis, clinical features, and recommended management.

A retrospective review of pharyngeal pouch surgery in 56 patients

We retrospectively reviewed 56 consecutive patients treated surgically for a pharyngeal pouch at our institution between 1989-1999 (10 years). Various surgical procedures were performed including endoscopic stapling (20), external excision (23), Dohlman's procedure (9), pouch inversion (3), cricopharyngeal myotomy only (3), and pouch suspension (1). There were 12 patients (18%) with complications and one mortality (2%). Four patients (7%) had a recurrence with 2 requiring further surgery. Over the latter 3 years, endoscopic stapling has emerged as the primary procedure for pharyngeal pouch surgery in our unit; with the advantages of an earlier commencement of diet and earlier hospital discharge. However, results were not as good as for external excisions. Furthermore, there were difficulties with 3 cases that commenced as endoscopic stapling procedures but had to he converted to external excisions due to inaccessibility in one case and iatrogenic perforations in two cases. As with any new technique, problems may occur and a learning curve has been appreciated in our unit. Surgeons must he prepared, with informed consent, to convert to an external approach should difficulties arise during endoscopic stapling. Elderly and frail patients who are at risk from a general anaesthetic may benefit from endoscopic stapling. External excision of pharyngeal pouches may be more appropriate in the young, the medically fit, and when malignancy is a concern.

The crucial role of imaging in detection of facial nerve haemangiomas

Facial nerve haemangioma is a rare benign neoplasm accounting for 0.7 per cent of all tumours involving the temporal bone. The diagnosis of a facial nerve tumour is often missed or delayed. Early diagnosis is imperative as it influences the eventual outcome for facial nerve function. Prognosis is related to the size of the tumour, the severity and the duration of pre-operative paralysis. The definitive diagnosis of a facial nerve tumour rests exclusively with high resolution imaging of the temporal bone using enhanced magnetic resonance imaging (MRI) and thin-sectioned computed tomography (CT). This case emphasizes the crucial role that high quality imaging can play in the diagnosis of facial nerve tumours, and elegantly illustrates the imaging features of facial nerve haemangiomas.

Middle cranial fossa approach for the repair of spontaneous cerebrospinal fluid otorrhoea using autologous bone pate

Tegmen plate defects causing cerebrospinal fluid (CSF) leaks and brain hernias have conventionally been repaired using soft tissue grafts by a transmastoid approach. A review of the literature reveals that the results of transmastoid repairs have been less than satisfactory. We present here four patients with spontaneous CSF otorrhoea who had tegmen defects repaired using the middle cranial fossa approach. An autologous bone pate slab mixed with fibrin glue with additional temporalis fascia reinforcement was used for the repairs. All four patients had uneventful postoperative periods and have had no subsequent CSF leak (follow-up range: 1-3 years). We believe that the middle cranial fossa approach is more effective than the transmastoid approach for the repair of CSF leaks and brain hernias through tegmen plate defects. An important additional benefit is hearing preservation. We also recommend the use of bone pate along with soft tissue for the repair in order to achieve a secure seal. Bone pate can effectively seal multiple defects in the tegmen plate without any risk of migration.

Total decompression of facial nerve for Melkersson-Rosenthal syndrome

Melkersson-Rosenthal syndrome (MRS) is a rare condition characterized by recurrent facial paralysis in addition to various orofacial manifestations. The condition appears to be a granulomatous disorder causing oedema and inflammation of the soft tissues of the face, lips, oral cavity and particularly, the facial nerve. There is general agreement that the symptoms and signs resolve spontaneously, aided perhaps by an empirical course of oral steroids. However, in some patients the condition may be progressive, leading to disfiguring facial synkinesis and increasing residual paralysis. There is anecdotal evidence in the literature to suggest that surgical decompression of the facial nerve in its entire intratemporal course may prevent further attacks of facial paralysis and its sequelae. We present here our experience with surgical decompression of the facial nerve in a 27-year-old woman with MRS who had sufferent recurrent left-sided facial palsy since the age of four. A review of the literature pertaining to facial nerve decompression for Melkersson-Rosenthal syndrome is presented.

Chronic cerebrospinal fluid leak into skull base causing intramedullary osteolysis

We present the rare case of a 74-year-old woman with extensive intramedullary osteolysis of the petroclival skull base straddling both sides of the basi-occiput and basi-sphenoid. She presented with clinical features of recurrent spontaneous cerebrospinal fluid (CSF) otorrhoea despite three previous attempts at repair of the CSF leak. Recent advances in imaging techniques enable accurate radiological diagnosis of skull base lesions. We performed T1- and T2-weighted magnetic resonance (MR) images, a fluid attenuated inversion recovery (FLAIR) sequence MR, and a diffusion scan to study the characteristics of the skull base pathology. This revealed extensive osteolysis, with cystic spaces within the clivus and the petrous pyramid extending also to the basi-occiput. The leak was sealed using the technique of subtotal petrosectomy with obliteration of the eustachian tube and blind pit closure of the ear canal. The patient has been followed up for six months with no recurrence of symptoms.

Positional vertigo as a first symptom of a cerebellopontine angle cholesteatoma: case report

We report a case of a cerebellopontine angle cholesteatoma whose initial sign was benign paroxysmal positional vertigo (BPPV). Positional vertigo caused by a central pathology is extremely rare and is usually accompanied by other suspicious features. In this case, there were no additional neurotologic symptoms or signs. The only abnormalities were seen on Dix-Hallpike testing, but because they were not consistent with a diagnosis of BPPV, the decision was made to proceed to imaging. Diagnostic rigor is required when evaluating positional vertigo, as with all symptoms of imbalance, if such cases are not to be overlooked.

Intraductal papilloma of the submandibular gland

Salivary tissue intraductal papillomas are rare, benign tumours that predominantly affect minor salivary glands. We report a case of an intraductal papilloma arising in the unusual site of the submandibular gland. The tumour was completely excised and recurrence is not expected. A brief review of this histologically distinct lesion is presented.

Desmoplastic fibroma of the temporal bone

An unusual case of a desmoplastic fibroma of the temporal bone is presented. Although classified benign, this intraosseous lesion exhibits local aggressiveness and has a high potential for recurrence. This rare condition occurs predominantly in the mandible and in the long bones and is seldom seen in the calvarium. Here we add another case to the previously described eight in the skull and this is the fourth such case reported in the temporal bone. The clinical features, radiology, histopathology and the therapeutic considerations of this lesion in a 72-year-old female are discussed. In addition, a literature review of all the cases affecting the skull bones is presented.

Is Ollier's disease an understaging of Maffucci's syndrome?

Ollier's disease and Maffucci's syndrome are similar multiple enchondromatous conditions. Other co-existing pathologies, particularly other primary malignancies, have been described sporadically in both conditions but more so in Maffucci's syndrome. Maffucci's syndrome is distinguished from Ollier's disease by the presence of haemangiomas in the former. In this report, a patient believed to have Ollier's disease for 44 years was subsequently found to have large splenic haemangiomas on magnetic resonance imaging (MRI). In the light of this, we recommend that any patient diagnosed with Ollier's disease to have total body MRI to search for haemangiomas that will alter the diagnosis to Maffucci's syndrome and hence the prognosis. MRI also screens for the presence of other associated malignancies.

Hearing preservation in patients undergoing vestibular schwannoma surgery: comparison of middle fossa and retrosigmoid approaches

OBJECT

The goal of this retrospective study was to evaluate hearing preservation after surgery for vestibular schwannoma in which the middle fossa (MF) or retrosigmoid (RS) approaches were used. Hearing preservation in vestibular schwannoma surgery can be achieved by using either the MR or RS approach. Comparative outcome data between these approaches are lacking, and, as a result, selection has generally been determined by the surgeon's preference.

METHODS

The authors have compared removal of small vestibular schwannomas via MF and RS approaches with regard to hearing preservation and facial nerve function. The study group was composed of consecutively treated patients with vestibular schwannoma, 48 of whom underwent operation via an MF approach and 50 of whom underwent the same number of RS operations. Tumors were divided into size-matched groups. Hearing results were recorded according to the American Academy of Otolaryngology-Head and Neck Surgery criteria, and facial nerve outcome was recorded as the House-Brackmann grade. Overall, 26 (52%) of the patients treated via the MF approach achieved a Class B or better hearing result compared with seven (14%) of the RS group. Some hearing was preserved in 32 (64%) of the patients in the MF group and in 17 (34%) of the RS group. The results obtained by using the MF approach were superior for intracanalicular tumors (p=0.009, t-test), and for tumors with a cerebellopontine angle (CPA) component measuring 0.1 to 1 cm (p=0.006, t-test). For tumors in the CPA that were 1.1 to 2 cm in size, our data were inconclusive because of the small sample size. Facial weakness was seen more frequently after MF surgery in the early postoperative period, but results were equal at 1 year.

CONCLUSIONS

The results of this study have demonstrated a more favorable hearing outcome for patients with intracanalicular tumors and tumors extending up to 1 cm into the CPA that were removed via the MF when compared with the RS approach.

Cystic fibrosis transmembrane conductance regulator gene mutations in severe nasal polyposis

A wide range of clinical phenotypes are associated with mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. In some cases, CFTR mutations have been identified in adults presenting with isolated features of cystic fibrosis such as mild lung disease, pancreatic insufficiency or male infertility, with normal sweat duct function. Nasal polyps are also a prominent feature of cystic fibrosis but it is unknown whether they also may represent a monosymptomatic form of the disease. We have screened the CFTR gene of 55 patients with severe nasal polyposis, who had no other features which would suggest a diagnosis of cystic fibrosis. The screening looked for mutations common to 86% of sufferers from cystic fibrosis. Three carriers were detected including one patient with the uncommon R117H mutation and two carriers of the delta F508 mutation. In addition there was one presumed carrier with a cystic fibrosis child, whose mutation we did not detect. This study has identified three CFTR mutation carriers in 55 patients with severe nasal polyposis. This is not significantly higher than the incidence in the general population. We cannot, from these figures, categorically rule out a slight association between CFTR mutations and simple nasal polyposis. However, we have demonstrated that the vast majority of patients with polyposis do not have inactivation of the CFTR gene.

Somatic neurofibromatosis type 2 gene mutations and growth characteristics in vestibular schwannoma

BACKGROUND

The growth of hereditary and sporadic vestibular schwannomas shows wide variation, but what determines this is poorly understood.

HYPOTHESIS

In neurofibromatosis type 2 (NF2), there is some correlation between the nature of the germline NF2 gene mutation and phenotype. Somatic mutations in the NF2 gene occur in sporadic tumors, but their relation to tumor behavior is unknown.

METHODS

This study has investigated the molecular pathogenesis of vestibular schwannoma by looking for NF2 gene mutations. The authors have screened 17 exons of the NF2 gene in 91 sporadic vestibular schwannomas, 2 NF2, and 1 vagal schwannoma. These data have been correlated with a clinical growth index and a tumor cell proliferation index, determined using a monoclonal antibody to the proliferating cell nuclear antigen.

RESULTS

Of the 94 tumors studied, 40 somatic gene mutations (38%) have been sequenced in 36 tumors. The mutations included 36 protein truncating mutations, 1 in-frame deletion, 2 splice site mutations, and 1 missense mutation. Regression analysis showed no correlation between the nature of the NF2 gene mutation and either the clinical (R2 = 0.006) or the proliferative index (R2 = 4 x 10(-8).

CONCLUSION

The results of this study show no association between the nature of the intragenic NF2 gene mutation and tumor behavior. It is likely therefore that NF2 gene inactivation is not the only determinant of tumor behavior in vestibular schwannoma.

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.

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.

Cochlear implantation in superficial siderosis

Superficial siderosis is a rare central nervous system disorder characterized by deafness, ataxia, and pyramidal signs. The hearing loss is believed to be predominantly neural and is usually progressive and bilateral. Careful assessment is therefore necessary to determine the best approach to hearing rehabilitation. A case is presented of superficial siderosis in a young woman who has benefitted significantly from cochlear implantation using the Nucleus device.

Laryngeal Kaposi's sarcoma in patients with AIDS

Over a period of 10 years 17 human immunodeficiency virus(HIV)-infected patients with laryngeal Kaposi's sarcoma were seen and treated at University College London Hospitals. All patients had advanced HIV disease. Their presentation was with symptoms of upper airway obstruction in the majority of cases and the diagnosis was made by fibreoptic examination of the larynx. Biopsy was associated with brisk haemorrhage in one patient, who required a temporary tracheostomy, and was not performed in the other 16 cases. The commonest site of laryngeal involvement was the supraglottis in 11 patients, with glottic lesions noted in eight patients: subglottic lesions were seen in only three. Treatment of laryngeal Kaposi's sarcoma was, in general, conservative, five patients received low dose radiotherapy to the larynx and 10 were treated with systemic chemotherapy for disseminated Kaposi's sarcoma. Laryngeal Kaposi's sarcoma did not contribute to patient mortality.

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.

Cochlear implants in chronic suppurative otitis media

Chronic suppurative otitis media (CSOM) in profoundly deaf patients is a contraindication for cochlear implantation. Eight (6%) of the 126 patients referred to cochlear implantation at this center between 1986 and 1992 became deafened as a result of bilateral CSOM but were otherwise suitable candidates. This study details the methods used in four patients to prepare the septic ear for a sterile device. Two patients had wet radical cavities with residual cholesteatoma, and two had discharging safe perforations resistant to surgical repair. Obliteration of the middle ear cleft with blind pit closure of the ear canal was attempted in all four patients, and cochlear implants were installed at a second operation 3 to 6 months later. The hearing results were as good as in implanted patients without CSOM, and the only complication has been the finding of a cholesteatoma pearl at the second operation in one patient. Fat obliteration of the mastoid and middle ear with blind pit closure of the ear canal can be adapted to make most chronic ears fit for implantation, if the patient is prepared to undergo two operations.

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.

The patient's perspective after vestibular schwannoma removal: quality of life and implications for management

A postal survey was conducted, using a standardized quality of life questionnaire, of patients who had undergone surgery for removal of vestibular schwannoma between 1981 and 1992. Of 257 questionnaires, 227 (88%) were returned completed. The questionnaire was based on the European Organisation for Research into the Treatment of Cancer (EORTC) core questionnaire. A series of five functional gradings were used to assess the quality of life, and specific questions were also asked. The results were numerically scored and have been correlated with patient and tumor characteristics. There was a significant difference (p = .0001) between the subjective functional outcome for small and intracanalicular tumors when compared with tumors larger than 1.5 cm maximum diameter. However, there was no significant difference when tumors 1.5 to 2.5 cm in diameter were compared to larger tumors. Poor functional outcome did not correlate with the age of the patient, position in the series, or postoperative facial nerve motor function. There also was no significant difference when younger patients (age < 65 yr) were compared with older patients (age 65 - 76 yr). In general, the quality of life following vestibular schwannoma surgery was excellent. Patients with a poor functional outcome were evenly distributed over the medium and large tumor size groups, and patients with small tumors ( < or = 1.5 cm) had a significantly better outcome.

The molecular genetics of vestibular schwannoma

Vestibular schwannoma occurs both as a sporadic tumour and in the dominantly inherited familial cancer syndrome neurofibromatosis type 2 (NF2). The gene for NF2 has recently been isolated on chromosome 22, and the demonstration of inactivating germline mutations in NF2 patients and NF2 associated tumours suggests that it acts as a tumour suppressor. The results of recent research in Cambridge suggest that somatic mutations of the NF2 tumour suppressor gene are a critical step in the pathogenesis of both familial and indeed non-familial unilateral sporadic vestibular schwannoma and that the mechanism of tumourigenesis complies with the 'two-hit' model. This paper represents a brief review of the current status of molecular biology in relation to vestibular schwannoma in particular and is discussed in relation to the molecular pathology of skull base tumours as a whole.

Genetics of familial and non-familial skull base tumours

Many tumours of the skull base, including schwannomas, paragangliomas, meningiomas and anterior pituitary tumours occur both as sporadic tumours and in clear cut familial syndromes. These cancers' highly penetrant dominantly inherited syndromes have proven to be a rich resource for locating tumour genes, most of which are of the tumour suppressor type. Recently, the gene for type 2 neurofibromatosis (NF2) was isolated by the technique of positional cloning. The NF2 gene has now been demonstrated to be involved in the pathogenesis of both familial and non-familial vestibular schwannomas as well as meningiomas. The presence of inactivating mutations within this gene suggests that it acts as a tumour suppressor and the mechanism has been shown to comply with a 'two hit' mutation model. Hereditary tumours constitute a small proportion of all cases, but evidence from studies of tumours such as vestibular schwannoma and meningioma have shown that their genes are also relevant to the much more common non-familial forms of the same tumour. This paper briefly describes the approach to locating tumour genes, and reviews our current knowledge regarding the chromosomal location and function of genes responsible for familial tumours involving the skull base. The genetic mechanisms of tumourigenesis are discussed as are the prospects for the development of novel forms of diagnosis and treatment.

Referral patterns in vestibular schwannomas

The investigation and treatment of vestibular schwannomas is an increasingly specialized area in which major advances have been seen over recent years. The effect of these advances on the referral patterns to a centre specializing in such surgery is reviewed. The proportion of referrals with a known diagnosis has increased substantially, allowing the specialist centre to focus on appropriate management rather than diagnosis. The vast majority of vestibular schwannomas are referred by otolaryngologists. The caseload referred by neurologists or neurosurgeons have different presenting symptoms. The incidence of vestibular schwannoma in the Cambridge district is found to be 1 per 50,000 population per year. This is a higher incidence than that recorded in other studies. This may be due to a tight diagnostic strategy and the high level of clinical awareness of the local general practitioners.

Audiological findings in glomus tumours

Glomus tumours of the skull base are rare, but as they present with symptoms of hearing loss and tinnitus they are a clinical entity of which audiologists should be aware. This paper describes the findings of the major series of skull base glomus tumours found in the literature, and notes that the contribution of conductive and sensorineural components varies with tumour classification. The reported incidence of hearing loss and tinnitus in glomus tympanicum and glomus jugulare is reviewed and compared with the Cambridge series, in which two tumours were Fisch type A, four type B, two type C and five type D. In each case a mixed hearing loss was found, though the extent of sensorineural impairment was variable. The length of history of tumours limited to the middle-ear was far shorter (mean 8 months) than for more extensive lesions (type B, mean 64 months; C, 48 months; and D, 23 months). Eleven patients (85%) reported the symptom of hearing loss, and 12 (92.5%) of tinnitus, and some patients had experienced these symptoms for some time without seeking the advice of an otologist. It may be concluded that the presence of subjective pulsatile tinnitus or a retrotympanic mass should be considered an indication for an otological opinion, wherein the use of high resolution imaging techniques and arteriography will be considered in conjunction with detailed audiological assessment. Audiologists should be aware of the possibility of glomus tumour in such cases.

Apo E genotypes in multiple sclerosis, Parkinson's disease, schwannomas and late-onset Alzheimer's disease

Apolipoprotein E (apo E) exists in three allelic, functionally distinct isoforms (apo E2, E3 and E4). Recent work has suggested that apo-E-dependent uptake of lipoproteins may play important roles in the development and maintenance of the nervous system and in the responses to both peripheral and central nervous system injury. If apo-E-mediated transport of lipids were a rate-limiting step in these processes, one might expect that the functional differences between the alleles would be associated with varying predispositions to neurodegenerative and demyelinating diseases. Thus, we looked for an association between particular apo E genotypes and susceptibility to multiple sclerosis and Parkinson's disease. If apo-E-mediated cholesterol uptake were limiting in neuronal growth, one might also expect that apo E2 alleles would slow CNS tumour growth. Accordingly, apo E genotypes were investigated in individuals with sporadic vestibular schwannomas and neurofibromatosis type 2 (NF-2). No significant alteration in the apo E allele distributions was observed in any of these conditions, nor did the apo E genotypes correlate with disease severity. However, we confirmed the previous findings of an over-representation of the apo E4 allele in autopsy-diagnosed late-onset Alzheimer's disease patients. In addition, our data supported the recent observations that apo E2 may be associated with a protective effect for late-onset Alzheimer's disease. These contrasting risks associated with the apo E2 and E4 alleles strengthen the suggestions that this gene is directly involved in the pathogenesis of Alzheimer's disease.

Mastoid obliteration using bone pâté

The technique of mastoid revision and obliteration using bone pâté and a superiorly based temporalis musculo-periosteal flap is described in detail. This method has evolved and been employed in our department over the past 10 years.