Neil Donnelly

MRI without magnet removal in neurofibromatosis type 2 patients with cochlear and auditory brainstem implants.

Objective To assess the impact on image quality of MRI without magnet removal in cochlear implant (CI) and auditory brainstem implant (ABI) users with neurofibromatosis type 2 (NF2). Study Design Prospective cohort. Setting Tertiary center for cochlear and auditory brainstem implantation. Patients Thirteen patients (10 ABI, 3CI) with NF2 underwent a total of 76 MRI scans. Interventions MRI without magnet removal. Main Outcome measure Ability to visualize the ipsilateral and contralateral cerebellopontine angles (CPAs) and internal auditory meati (IAM) with head MRI. Results Of the 76 scans, 40 were of the head, 28 of the spine and 8 of other regions. Scanning was performed with a tight head bandage and plastic card. There were no cases of altered implant function or demagnetization of the device magnet. A grading system was used to assess the view of the ipsilateral IAM-CPA. In 85% of head scans, the view was unimpaired (Grade 0). In 13%, there was distortion (Grade 1). In 2% (1 case), the view was entirely obscured by artifact (Grade 2). Views of the contralateral CPA and IAM were unimpaired in all cases. The best 3 sequences for the depiction of the ipsilateral IAM-CPA (percent graded as 0) were as follows: axial 3D inversion recovery prepared fast spoiled gradient echo (100%), 2 mm coronal T1W of the IAM-CPA (88.9%), and 2 mm axial T1W of the IAM-CPA (76.9%). Conclusion MRI scanning without magnet removal is safe and well tolerated in NF2 patients with auditory implants. With appropriate MRI sequences, the image quality is not significantly impaired.

Non echo planar, diffusion-weighted magnetic resonance imaging (periodically rotated overlapping parallel lines with enhanced reconstruction sequence) compared with echo planar imaging for the detection of middle-ear cholesteatoma

OBJECTIVES We evaluated use of the periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted imaging sequence, compared with conventional echo planar magnetic resonance imaging, in the detection of middle-ear cholesteatoma. MATERIAL AND METHODS Sixteen patients awaiting second-stage combined approach tympanoplasty and three patients awaiting first-stage combined approach tympanoplasty underwent magnetic resonance imaging with both (1) the periodically rotated overlapping parallel lines with enhanced reconstruction sequence (i.e. non echo planar imaging) and (2) the array spatial sensitivity encoding technique sequence (i.e. echo planar imaging). Two neuroradiologists independently evaluated the images produced by both sequences. Radiology findings were correlated with surgical findings. RESULTS AND ANALYSIS Seven cholesteatomas were found at surgery. Neither of the assessed imaging sequences were able to detect cholesteatoma of less than 4 mm. Rates for sensitivity, specificity, and positive and negative predictive values are presented. CONCLUSION Decisions on whether or not to operate for cholesteatoma cannot be made based on the two imaging sequences assessed, as evaluated in this study. Other contributing factors are discussed, such as the radiological learning curve and technical limitations of the magnetic resonance imaging equipment.

Equivalent Noise Level Generated by Drilling Onto the Ossicular Chain as Measured by Laser Doppler Vibrometry: A Temporal Bone Study†

Background: Inadvertent drilling on the ossicular chain is one of the causes of sensorineural hearing loss (HL) that may follow tympanomastoid surgery. A high‐frequency HL is most frequently observed. It is speculated that the HL is a result of vibration of the ossicular chain resembling acoustic noise trauma. It is generally considered that using a large cutting burr is more likely to cause damage than a small diamond burr.

Surgical management of vestibular schwannomas and hearing rehabilitation in neurofibromatosis type 2.

Objectives To report our approach to the surgical management of vestibular schwannomas (VSs) and hearing rehabilitation in neurofibromatosis Type 2 (NF2). Design Retrospective cohort study. Setting Tertiary referral NF2 unit. Patients Between 1981 and 2011, seventy-five patients were managed in our NF2 unit, of which, 58 patients are under current review. Main Outcome Measures Patients who underwent VS excision were evaluated for tumor size, surgical approach, and outcomes of hearing and facial nerve function. All current patients were evaluated for NF2 mutation, hearing, and auditory implantation outcomes. Results Forty-four patients underwent resection of 50 VS in our unit, of which, 14% had facial neuroma excision and reinnervation during the same operation. At 12 months after surgery, facial nerve outcomes were House-Brackmann (HB) 1 in 33%, HB2 in 21%, and HB3 in 30%. Total VS resection was achieved in 78% of patients using a translabyrinthine approach. Seventy-two percent of the current patients have American Association of Otolaryngology–Head and Neck Surgery class A to C hearing (maximum speech discrimination score over 50%) in the better hearing ear, and a further 14% are full-time users of cochlear implants or auditory brainstem implants. The remaining patients have been assessed for auditory implantation. Conclusion By following a policy of treating VS in NF2 patients where tumor growth is observed, complete tumor resection can be achieved through a translabyrinthine approach while achieving comparable facial nerve outcomes to published series. We advocate proactive hearing rehabilitation in all patients with timely assessment for auditory implantation to maintain quality of life.

English consensus protocol evaluating candidacy for auditory brainstem and cochlear implantation in neurofibromatosis type 2

Objective Hearing loss resulting from bilateral vestibular schwannomas (VSs) has a significant effect on the quality of life of patients with neurofibromatosis Type 2 (NF2). A national consensus protocol was produced in England as a guide for cochlear implantation (CI) and auditory brainstem implantation (ABI) in these patients. Study Design Consensus statement. Setting English NF2 Service. Participants Clinicians from all 4 lead NF2 units in England. Main Outcome Measures A protocol for the assessment, insertion and rehabilitation of CI and ABI in NF2 patients. Results Patients should undergo more detailed hearing assessment once their maximum aided speech discrimination score falls below 50% in the better hearing ear. Bamford-Kowal-Bench sentence testing scores below 50% should trigger assessment for auditory implantation, as recommended by the National Institute for Clinical Excellence guidelines on CI. Where this occurs in patients with bilateral stable VS or a unilateral stable VS where the contralateral cochlear nerve was lost at previous surgery, CI should be considered. Where VS surgery is planned, CI should be considered where cochlear nerve preservation is thought possible, otherwise an ABI should be considered. Intraoperative testing using electrically evoked auditory brainstem responses or cochlear nerve action potentials may be used to determine whether a CI or ABI is inserted. Conclusion The NF2 centers in England agreed on this protocol. Multisite, prospective assessments of standardized protocols for auditory implantation in NF2 provide an essential model for evaluating candidacy and outcomes in this challenging patient population.

Squamous Cell Carcinoma of the Temporal Bone: Clinical Outcomes From Radical Surgery and Postoperative Radiotherapy

Objective To review the treatment of squamous carcinoma of the temporal bone at a regional skull base unit for the period 1982–2012. Study Design Retrospective case review. Setting Tertiary referral center. Patients Sixty patients with primary squamous carcinoma of the temporal bone. Interventions Multidisciplinary team approach including surgical resection, reconstruction, and postoperative radiotherapy. Main Outcome Measures Disease-specific survival, overall survival. Results The 5-year disease-specific survival for the whole cohort was 44% (CI, 37%–51%). Multivariable analysis revealed nodal status, poorly differentiated squamous cell histology, and carotid involvement to be poor prognostic indicators. Conclusion Although the survival figures in this series are comparable with the best outcomes from other units, our experience would suggest improvements can still be achieved by reconsidering the selection of patients for neck dissection and temperomandibular joint excision in early stage disease. We also conclude that postoperative radiotherapy should be delivered to all patients, including surgical salvage cases who may have received previous irradiation. Finally, the minority of patients with poor prognostic features should be offered a more palliative therapeutic approach.

Immunoglobulin G4 related systemic sclerosing disease involving the temporal bone

OBJECTIVE To report a rare condition affecting the temporal bone. Immunoglobulin G4 related systemic sclerosing disease is a recently described autoimmune condition with manifestations typically involving the pancreas, biliary system, salivary glands, lungs, kidneys and prostate. Histologically, it is characterised by T-cell infiltration, fibrosis and numerous immunoglobulin G4-positive plasma cells. This condition previously fell under the umbrella diagnosis of inflammatory pseudotumour and inflammatory myofibroblastic tumour. CASE REPORT We present the case of a 58-year-old woman with multiple inflammatory masses involving the pharynx, gall bladder, lungs, pelvis, omentum, eyes and left temporal bone, over a seven-year period. We describe this patients unusual clinical course and pathological features, which resulted in a change of diagnosis from metastatic inflammatory myofibroblastic tumour to immunoglobulin G4 related systemic sclerosing disease. We also review the literature regarding the management of inflammatory pseudotumours of the temporal bone, and how this differs from the management of immunoglobulin G4 related systemic sclerosing disease. CONCLUSION We would recommend a full review of all histological specimens in patients with a diagnosis of temporal bone inflammatory pseudotumour or inflammatory myofibroblastic tumour. Consideration should be given to immunohistochemical analysis for anaplastic lymphoma kinase and immunoglobulin G4, with measurement of serum levels of the latter. Management of the condition is medical, with corticosteroids and immunosuppression, rather than surgical excision.

Effect of cochlear implant electrode insertion on middle-ear function as measured by intra-operative laser Doppler vibrometry.

HYPOTHESIS The aim of this study was to investigate the impact of cochlear implant electrode insertion on middle-ear low frequency function in humans. BACKGROUND Preservation of residual low frequency hearing with addition of electrical speech processing can improve the speech perception abilities and hearing in noise of cochlear implant users. Preservation of low frequency hearing requires an intact middle-ear conductive mechanism in addition to intact inner-ear mechanisms. Little is known about the effect of a cochlear implant electrode on middle-ear function. METHODS Stapes displacement was measured in seven patients undergoing cochlear implantation. Measurements were carried out intra-operatively before and after electrode insertion. Each patient acted as his or her own control. Sound was delivered into the external auditory canal via a speaker and calibrated via a probe microphone. The speaker and probe microphone were integrated into an individually custom-made ear mould. Ossicular displacement in response to a multisine stimulus at 80 dB SPL was measured at the incudostapedial joint via the posterior tympanotomy, using an operating microscope mounted laser Doppler vibrometry system. RESULTS Insertion of a cochlear implant electrode into the scala tympani had a variable effect on stapes displacement. In three patients, there was little change in stapes displacement following electrode insertion. In two patients, there was a significant increase, while in a further two there was a significant reduction in stapes displacement. This variability may reflect alteration of cochlear impedance, possibly due to differing loss of perilymph associated with the electrode insertion. CONCLUSION Insertion of a cochlear implant electrode produces a change in stapes displacement at low frequencies, which may have an effect on residual low frequency hearing thresholds.

Characterizing human vestibular sensory epithelia for experimental studies: new hair bundles on old tissue and implications for therapeutic interventions in ageing

Balance disequilibrium is a significant contributor to falls in the elderly. The most common cause of balance dysfunction is loss of sensory cells from the vestibular sensory epithelia of the inner ear. However, inaccessibility of inner ear tissue in humans severely restricts possibilities for experimental manipulation to develop therapies to ameliorate this loss. We provide a structural and functional analysis of human vestibular sensory epithelia harvested at trans-labyrinthine surgery. We demonstrate the viability of the tissue and labeling with specific markers of hair cell function and of ion homeostasis in the epithelium. Samples obtained from the oldest patients revealed a significant loss of hair cells across the tissue surface, but we found immature hair bundles present in epithelia harvested from patients >60 years of age. These results suggest that the environment of the human vestibular sensory epithelium could be responsive to stimulation of developmental pathways to enhance hair cell regeneration, as has been demonstrated successfully in the vestibular organs of adult mice.

Outcome of translabyrinthine surgery for vestibular schwannoma in neurofibromatosis type 2

Abstract 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.