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Biomedical subjects

D A Moffat

Publications and source records attributed to D A Moffat.

At least 19 recordsLinked to original sources
PubMed1998

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.

Adult↗
PubMed1998

Clinical acumen and vestibular schwannoma.

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.

Adolescent↗
PubMed1998

An alternative method for dealing with cerebrospinal fluid fistulae in inner ear deformities.

OBJECTIVE: This study aimed to review the management of cerebrospinal fluid (CSF) fistulae in the setting of developmental inner ear deformity. STUDY DESIGN: The study design was a case review, close examination of preoperative radiology, and corresponding intraoperative images. TECHNIQUE: A definitive method of CSF fistula closure is described using previously known techniques used commonly in skull base surgery. CONCLUSIONS: The use of a multiple-level, reinforced wound closure technique is necessary to definitively close CSF fistulae in extreme inner ear deformity and to prevent further episodes of CSF leak and meningitis.

Audiometry, Pure-Tone↗
PubMed1997

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.

Adult↗
PubMed1997

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.

Adult↗
PubMed1997

Chondrosarcoma of the petrous apex. Dilemmas in diagnosis and treatment.

A case of chrondrosarcoma of the petrous temporal bone is presented. Chondrosarcomas rarely occur intracranially and typically present apex mass. The dilemmas faced in the diagnosis and treatment of petrous apex chondrosarcomas are discussed. This case also gives interesting insight into the natural history of this tumour.

Chondrosarcoma↗
PubMed1997

Audio-vestibular findings in meningioma of the cerebello-pontine angle: a retrospective review.

The aim of this study was the determination of the incidence of symptoms of audio-vestibular dysfunction and of abnormalities on audio-vestibular testing in patients found to have a unilateral meningioma of the cerebello-pontine angle (CPA). The case notes of 25 patients diagnosed with unilateral, sporadic and histologically proven CPA meningioma were retrospectively reviewed. The age range of this series was 31-71 years, with a mean age of 50 years. Two patients were male (eight per cent) and 23 were female (92 per cent). The mean length of history was 44.7 months. The distribution of tumour size was skewed toward larger tumours, with 15 cases (60 per cent) having tumours with a maximum diameter greater than 3.5 cm on imaging. Pure tone audiometry was normal in five cases (20 per cent), and no patients exhibited the high frequency sensorineural hearing loss that is characteristic of vestibular schwannoma. Speech audiometry was normal in 50 per cent of cases. Caloric testing was abnormal in 77 per cent of the 18 cases tested, whilst auditory brainstem responses (ABR) were abnormal in 100 per cent of the 18 cases who had sufficient hearing for this test to be possible. The presence of normal audiometry in patients with a proven CPA lesion indicates that, if in a protocol for investigation, asymmetry of hearing is mandatory then some pathology will be missed. Any suspicion of a CPA lesion warrants investigation even in the absence of hearing loss. The investigation of choice for the identification of CPA lesions has become magnetic resonance imaging (MRI). If this technique is not available then this study indicates that ABR is a suitable and sensitive investigation. It should be borne in mind however that the data in this study has been derived from a series of predominantly large tumours, and the sensitivity of ABR to smaller CPA meningiomata may fall, as is the case for vestibular schwannoma.

Adult↗
PubMed1997

Endolymphatic mastoid shunt surgery in unilateral Menière's disease.

One-hundred endolymphatic mastoid shunt operations in patients with classic unilateral Meniere's disease were analyzed. The patients were carefully preselected with a comprehensive protocol of audiovestibular and metabolic investigations. All patients had definitive electrophysiologic evidence of endolymphatic hydrops with an enhanced negative summating potential on transtympanic electrocochleography. The surgical results were analyzed both by the original American Academy of Ophthalmology and Otolaryngology Guidelines (AAOO, 1972), and the more recent modifications of the American Academy of Otolaryngology-Head and Neck Surgery (AA-HNS, 1985). Control of vertigo was achieved in 79% of the patients overall, with 42% sustaining complete control and 37% substantial control. A significant hearing improvement was obtained in 15% of cases, there was no change in 56% of patients, and hearing became worse in 29%. Tinnitus improved following surgery in 35% of patients, was the same in 56%, and worse in 9%. Postoperatively, there was no disability in 42% of the patients, some degree of disability in 50%, and severe disability and inability to sustain gainful employment in only 8%.

Adolescent↗
PubMed1997

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.

Adult↗
PubMed1996

Epithelial-myoepithelial carcinoma of the parotid gland. An unusual cause of ear canal stenosis.

Epithelial-myoepithelial carcinoma (EMC) accounts for approximately one per cent of salivary gland tumours. This tumour is gaining wider recognition following inclusion into the WHO histological classification of salivary gland tumours in 1990. Salivary gland tumours characteristically present with an enlarging mass. We describe an unusual presentation of a salivary gland tumour with stenosis of the external ear canal in the absence of a palpable mass. EMC usually arises from the salivary glands but isolated cases have been described arising primarily from the paranasal sinuses, trachea and lacrimal gland. The management of this tumour is still evolving with surgical excision being the main-stay of treatment. The efficacy of radiotherapy has not yet been established but high local recurrence rates despite apparently adequate excision and the possibility of a multicentric origin of the tumour may herald an increasing role for radiotherapy in the future. We stress the importance of awareness of adjacent structures when considering the cause of cartilaginous canal stenosis.

Carcinoma↗
PubMed1996

Factors which influence the facial nerve outcome in vestibular schwannoma surgery.

A series of 276 patients with a unilateral vestibular schwannoma has been analysed with respect to the factors affecting post-operative facial nerve outcome. Age, tumour size, operative approach and the use of intra-operative facial nerve monitoring have been examined. The tumours were removed via either a translabyrinthine or a retrosigmoid approach. In this series increasing age and increasing tumour size were associated with a worse facial nerve outcome. The use of intra-operative facial nerve monitoring and the retrosigmoid approach were both associated with a better facial nerve outcome. Those patients having a retrosigmoid approach had a facial nerve result that was over one House grade better than those having translabyrinthine tumour removal.

Facial Nerve↗
PubMed1996

The surgical management of patients with glomus tumours of the skull base.

Total surgical excision is the only treatment modality that offers a cure for patients with glomus tumours of the skull base. The vascularity, inaccessibility and frequently extensive local spread, all contribute to the difficulties encountered in the management of patients with these complex lesions. Owing to the rarity of skull base glomus tumours, experience in their management can only be attained over long periods of time. We describe the surgical management of 20 patients with large glomus tumours of the skull base treated by an otoneurosurgical team over an 11-year period. Overall, 70% of patients had an excellent outcome, 10% a good outcome and 20% a poor outcome at a mean follow-up of 3.1 years. Poor outcomes were due to severe facial nerve palsies in two cases, and poorly accommodated palsies of the bulbar cranial nerves in a further two patients. The management of postoperative neurological deficits is discussed in detail. We conclude that in the majority of patients with skull base glomus tumours, complete surgical excision can be safely achieved.

Adult↗
PubMed1996

Surgical results in unusual cerebellopontine angle tumours.

Vestibular schwannomas account for 84% of cerebellopontine angle (CPA) lesions. The remaining CPA tumours comprise a fascinating group of lesions which may present in a similar fashion. Fortunately, advances in neuroradiology have increased our diagnostic accuracy of these lesions. This paper describes the surgical results of a series of 69 CPA lesions which were not vestibular schwannomas. The majority of these unusual CPA tumours were meningiomas, cholesteatomas and neuromas of other cranial nerves in the posterior fossa.

Adult↗
PubMed1996

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.

Chromosomes, Human, Pair 22↗
PubMed1996

Audiovestibular results after surgery for cerebellopontine angle meningiomas.

Meningiomas are the second most common cerebellopontine angle (CPA) tumor. The reported rates of hearing preservation following surgical removal vary between 32% and 100%. There is only one recent report discussing vestibular function after CPA meningioma removal. In this series of 31 patients with CPA meningiomas, 16 patients had their tumors removed via the retrosigmoid approach. All 16 had audiovestibular assessment pre- and postsurgery and were the subjects of this study. Class A hearing is socially useful hearing and is defined as a pure tone average (PTA; average of 500 Hz and 1, 2 and 4 kHz) of < 30 dB and speech discrimination scores (SDS) of > 70%. Class B hearing is serviceable hearing, defined as PTA of < 50 dB and SDS of > 50%. Nine patients had class A hearing, and two had class B hearing presurgery. Socially useful hearing was preserved in six of nine (67%) patients in whom it was present before surgery, and serviceable or better hearing was preserved in eight of 11 (73%). Vestibular symptomatology and examination findings improved despite a decrease in the number of patients with intact caloric function postsurgery. Patients who retained vestibular function on caloric testing were symptomatically better than those who lost caloric function. These results confirm that excellent audiovestibular function is possible after CPA meningioma surgery.

Adult↗
PubMed1996

The operative learning curve and its effect on facial nerve outcome in vestibular schwannoma surgery.

The successful removal of vestibular schwannomas requires a team approach by skillful and appropriately trained surgeons. It is generally perceived that the results of surgery, especially facial nerve outcome, will improve as the surgical team acquires more experience. This study of 300 patients undergoing surgical removal of vestibular schwannomas confirms that there was a significant learning curve for facial nerve outcome. In the first 50 cases, 52% had satisfactory outcomes (House grades I-III), whereas in the last 50 cases 92% had satisfactory outcomes. The major improvement came between the first 50 cases and the second 50 cases (House grades I-III results at 12 months improved from 52% to 78%). After the second 50 patients there was a gradual, but continued improvement, which is also attributable to increased surgical experience. Most of this learning curve was related to the translabyrinthine approach. House grades I-III results were attained for 45% of the first 40 and 70% of the second 40 translabyrinthine tumor removals.

Ear Neoplasms↗