Richard M. Irving

Radiologic Differentiation of Intracranial Epidermoids from Arachnoid Cysts

Objective Intracranial epidermoids (cholesteatomas) mimic arachnoid cysts in their radiologic characteristics, especially in the cerebellopontine angle. It is essential to differentiate the two conditions because they warrant different therapeutic interventions. The objective of this study is to elucidate the different radiologic characteristics of the conditions. Study Design and Setting This was a retrospective study of 4 patients referred for a differential diagnosis and management of intracranial cystic lesions to the Departments of Neurotology/Neurosurgery and Neuroradiology in a tertiary referral university hospital. Patients Four patients of different age groups with cystic intracranial lesions, diagnosed epidermoid or arachnoid cysts, were chosen. A retrospective analysis of their case charts, radiologic and surgical interventions, and follow-up records was undertaken. Methods The imaging techniques used included computerized tomographic scans, magnetic resonance imaging (MRI) with T1, T2, proton-density, and gadolinium-enhanced T1 images. In addition, special MRI sequences were used that included fluid-attenuated inversion recovery and echo planar diffusion scanning. All the patients underwent an audiovestibular evaluation. Results Both lesions are characteristically well demarcated and have a homogeneous low density, similar to cerebrospinal fluid on computerized tomographic scan, showing no contrast enhancement. On MRI, epidermoids and arachnoid cysts usually appear hypointense on T1-weighted images and hyperintense on T2-weighted images. On fluid-attenuated inversion recovery, an arachnoid cyst tends to follow cerebrospinal fluid intensity, whereas an epidermoid becomes hyperintense. There are occasions when an epidermoid may appear as a low-intensity lesion on fluid-attenuated inversion recovery. This dilemma is resolved with the use of echo planar diffusion scanning, on which an epidermoid remains bright. Conclusion The authors recommend the use of fluid-attenuated inversion recovery and diffusion sequence MRI when definitive radiologic diagnosis of cystic intracranial lesions becomes difficult with routine computerized tomographic scanning and MRI.

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.

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

Clin. Otolaryngol. 2010, 35, 284–290

Diffusion-weighted magnetic resonance imaging in the management of cholesteatoma

Diffusion-weighted (DW) MRI has recently increasingly gained popularity in the diagnosis of post-operative cholesteatoma. The aim of this study is to prospectively evaluate the usefulness of echo-planar imaging (EPI) for the diagnosis of residual cholesteatoma. Fifty patients underwent DW-EPI before surgery. Fifteen patients had a scan before their first surgery and 35 patients underwent neuroimaging prior to their second look surgery. In the first preoperative group of 15 patients, DW-EPI confirmed cholesteatoma in all the patients. In the post-operative group DW-EPI identified or excluded cholesteatoma correctly in 29 out of 35 patients. Our study has demonstrated a sensitivity of 83% and specificity of 82% of DW-EPI for the diagnosis of residual cholesteatoma. DW-EPI can be a value imaging modality and may help the surgeon in selecting patients for revision surgery.

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.

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

Clin. Otolaryngol. 2010, 35, 284–290

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 implants to treat deafness caused by vestibular schwannomas.

Objective Rehabilitation of hearing is complicated in patients with profound bilateral hearing loss in the presence of sporadic vestibular schwannoma (VS) or neurofibromatosis 2 (NF2), especially if the tumor does not need to be removed. We present the outcome of patients who have had a cochlear implant in the tumor affected ear without removal of the primary tumor. Design This is a retrospective multicentre study investigating outcomes of cochlear implantation in profoundly deaf patients with vestibular schwannoma in the implanted ear. Materials and Methods Out of 11 implanted patients, 5 required no treatment for their tumor, whereas 6 had previously undergone radiotherapy. Nine patients experienced NF2, and 2 had unilateral VS in the only hearing ear. Postoperative hearing was assessed with open and closed set speech discrimination, including City University of New York (CUNY) in noise and Bamford, Kowal and Bench (BKB) sentence scores. Results Patients with untreated lesions experienced marked improvement in their BKB and CUNY scores in the implanted ear and were daily cochlear implant users. The improvement was less consistent in the patients who had radiotherapy where only 1 patient attained open set speech discrimination. Conclusion Patients with unilateral VS (sporadic or those affected with NF2) whose tumor status was stable, benefited from cochlear implantation in their tumor-affected ear. Patients who had radiotherapy also benefited from CI, but their outcomes were variable.

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.

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 Dohlmans 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.