Scalar localisation of peri-modiolar electrodes and speech perception outcomes.

OBJECTIVE: To identify the intracochlear electrode position in cochlear implant recipients and determine the correlation to speech perception for two peri-modiolar electrode arrays. METHODS: Post-operative cone-beam computed tomography images of 92 adult recipients of the 'CI512' electrode and 18 adult recipients of the 'CI532' electrode were analysed. Phonemes scores were recorded pre-implantation, and at 3 and 12 months post-implantation. RESULTS: All CI532 electrodes were wholly within scala tympani. Of the 79 CI512 electrodes intended to be in scala tympani, 58 (73 per cent) were in scala tympani, 14 (17 per cent) were translocated and 7 (9 per cent) were wholly in scala vestibuli. Thirteen CI512 electrodes were deliberately inserted into scala vestibuli. Speech perception scores for post-lingual recipients were higher in the scala tympani group (69.1 per cent) compared with the scala vestibuli (54.2 per cent) and translocation (50 per cent) groups (p < 0.05). Electrode location outside of scala tympani independently resulted in a 10.5 per cent decrease in phoneme scores. CONCLUSION: Cone-beam computed tomography was valuable for demonstrating electrode position. The rate of scala tympani insertion was higher in CI532 than in CI512 electrodes. Scala vestibuli insertion and translocation were associated with poorer speech perception outcomes.

Co-registration of cone beam CT and preoperative MRI for improved accuracy of electrode localization following cochlear implantation.

OBJECTIVES: To investigate the clinical usefulness and practicality of co-registration of Cone Beam CT (CBCT) with preoperative Magnetic Resonance Imaging (MRI) for intracochlear localization of electrodes after cochlear implantation. METHODS: Images of 20 adult patients who underwent CBCT after implantation were co-registered with preoperative MRI scans. Time taken for co-registration was recorded. The images were analysed by clinicians of varying levels of expertise to determine electrode position and ease of interpretation. RESULTS: After a short learning curve, the average co-registration time was 10.78 minutes (StdDev 2.37). All clinicians found the co-registered images easier to interpret than CBCT alone. The mean concordance of CBCT vs. co-registered image analysis between consultant otologists was 60% (17-100%) and 86% (60-100%), respectively. The sensitivity and specificity for CBCT to identify Scala Vestibuli insertion or translocation was 100 and 75%, respectively. The negative predictive value was 100%. DISCUSSION: CBCT should be performed following adult cochlear implantation for audit and quality control of surgical technique. If SV insertion or translocation is suspected, co-registration with preoperative MRI should be performed to enable easier analysis. There will be a learning curve for this process in terms of both the co-registration and the interpretation of images by clinicians.

Method transfer, partial validation, and cross validation: recommendations for best practices and harmonization from the global bioanalysis consortium harmonization team.

This paper presents the recommendations of the Global Bioanalytical Consortium Harmonization Team on method transfer, partial validation, and cross validation. These aspects of bioanalytical method validation, while important, have received little detailed attention in recent years. The team has attempted to define, separate, and describe these related activities, and present practical guidance in how to apply these techniques.

Primary melanoma of the cochlea with cerebellopontine extension and leptomeningeal spread.

BACKGROUND: Less than 1 per cent of tumours occurring in the region encompassing the internal auditory canal and the cerebellopontine angle are malignant. Primary central nervous system melanomas arising from this region are exceptionally rare and are often initially misdiagnosed as acoustic neuromas. METHODS: We present a 71-year-old man with acute vestibular disturbance and unilateral hearing loss. Magnetic resonance imaging demonstrated a mass, thought to be a cochlear nerve schwannoma, involving the cochlea and the internal auditory canal. At surgery, a pigmented mass adherent to the facial nerve was visualised, and the observed histopathology was consistent with a malignant melanoma. No extracranial site for the primary tumour was found, suggestive of a primary central nervous system melanoma. RESULTS: Despite surgical resection and adjuvant radiotherapy, the patient re-presented with extensive leptomeningeal disease 16 months later. CONCLUSION: Malignant tumours in the internal auditory canal and cerebellopontine angle region are rare. Early diagnosis and management are aided by recognition of characteristic factors such as a history of prior malignancy, atypical magnetic resonance imaging findings and accelerated audiovestibular symptoms. Despite the presented patient's outcome, total surgical resection with post-operative radiotherapy remains the recommended treatment.

Factors associated with symptom-specific psychological and functional impact among acoustic neuroma patients.

INTRODUCTION: The main purpose of this study was to investigate the psychological and functional impact attributed to acoustic neuroma symptoms. MATERIALS AND METHODS: A sample of 207 acoustic neuroma patients completed a study-specific questionnaire about the severity, frequency, and psychological and functional impact of 9 acoustic neuroma symptoms. RESULTS: The survey response rate was 56.4 per cent. All symptoms had some degree of psychological impact for the majority of participants; hearing loss was the symptom most often reported to have a severe psychological impact. The majority of respondents reported functional impact attributed to hearing loss, balance disturbance, dizziness, eye problems, headache and fatigue; balance disturbance was the symptom most often reported to have a severe functional impact. For most symptoms, psychological and functional impact were related to severity and frequency. CONCLUSION: Of the acoustic neuroma symptoms investigated, hearing loss and balance disturbance were the most likely to have a severe psychological and functional impact, respectively.

Factors associated with anxiety and depression in the management of acoustic neuroma patients.

The objectives of this study were to describe anxiety and depression levels among acoustic neuroma patients; examine differences in anxiety and depression across the acoustic neuroma management options of microsurgery, radiation and observation; and to investigate management, medical and demographic factors that might predict anxiety and depression in this patient group. A cross-sectional questionnaire was completed by 205 adults diagnosed with, or treated for, a unilateral acoustic neuroma within five years of questionnaire distribution. Median age of participants was 57.0 years, and 120 (58.5%) were female. Anxiety and depression were measured using the Hospital Anxiety and Depression Scale (HADS). Clinically significant anxiety was reported by 29.8% of participants and 10.2% were depressed. Mean anxiety and depression scores did not differ from general population norms. No significant differences in anxiety and depression were found across management options. Time since management, number of symptoms and comorbid medical conditions predicted anxiety, while depression was predicted by number of symptoms. This appears to be the first study among acoustic neuroma patients in which anxiety and depression were compared across management options. Treating physicians should be aware that as the number of acoustic neuroma symptoms increases, so may the likelihood of clinically significant anxiety and depression.

Methylprednisolone applied directly to the round window reduces dizziness after cochlear implantation: a randomized clinical trial.

This prospective, double-blind controlled, randomized clinical trial of 43 adults showed that topical methylprednisolone applied to the round window during cochlear implantation was effective in protecting inner ear function. Postoperative vestibular disturbance was significantly lower in the steroid group (5%) than the control group (29%). Electrode impedances from the middle portion of the electrode array (electrodes 10-13) were significantly reduced in steroid-treated recipients compared to controls. Hearing and vestibular function analyses were under-powered to detect any drug changes due to limited participant data.

Diagnosis and outcomes of middle cranial fossa repair for patients with superior semicircular canal dehiscence syndrome.

The aim of this study was to retrospectively review the clinical presentation, diagnostic features, in particular cervical vestibular evoked myogenic potentials (cVEMPs), and the outcomes of surgical repair for superior semicircular canal dehiscence syndrome (SSCDS). SSCDS is a well-described syndrome of auditory and vestibular symptoms due to a bony dehiscence of the superior semicircular canal in the middle cranial fossa. A series of six procedures on five patients with SSCDS who underwent surgical repair via a middle fossa craniotomy were retrospectively reviewed. Preoperative and postoperative audiometric and vestibular symptoms as well as investigation findings were reviewed. Auditory and vestibular symptoms improved and hearing was preserved in all patients. The low frequency pseudo-conductive loss was corrected in four out of five patients, and the lowered preoperative cVEMP thresholds normalised following successful middle cranial fossa repair. In this series, middle fossa repair of SSCD was safe and effective with excellent sensorineural hearing preservation.

The prognostic value of speech recognition scores at diagnosis of vestibular schwannoma.

We aimed to assess whether speech recognition scores (SRS) are predictive of outcomes in patients with small vestibular schwannoma (VS) undergoing observation. Ninety-five patients with VS whose initial management was observation with serial imaging were retrospectively analysed. Patients were divided into groups according to their average hearing level and SRS at diagnosis. About 60% of patients had good initial SRS (GIS) and 40% had poor initial SRS (PIS). Mean follow-up was 44 months, during which time data were collected regarding hearing level, tumour growth and the eventual management option (continued or failed observation). Observation was discontinued by 24% (23/95) of patients. GIS-patients were more likely to maintain stable hearing than those with PIS (p<0.05). Hearing was stable in 73% (64/87) of patients. These findings indicate that patients with PIS are more vulnerable to progressive hearing loss than those with GIS. Observation may be a suitable management option for all patients with small VS, particularly those with GIS.

Classification of cochlear implant failures and explantation: the Melbourne experience, 1982-2006.

The definition and categorization of reasons for cochlear implant (CI) failure have recently been standardized following the publication of the European Consensus Statement on Cochlear Implant Failures and Explantation (ECSCIFE) (2005). The aim of this study was to review the Melbourne experience with cochlear implant failure and reimplantation, applying ECSCIFE guidelines for categorization and assessing hearing outcomes. A retrospective review was carried out of Melbourne CI clinic's records to identify all cases of implant failure and categorize them using ECSCIFE guidelines. Comparison was made of pre- and post-reimplantation hearing levels for those patients who had undergone ipsilateral reimplantation. Between September 1982 and October 2006 the Melbourne clinic conducted 1164 CIs with 62 implant failures and explantation (5.3%). Reasons included device failure, (ECSCIFE category C, n = 35, 3.0%), medical complication (ECSCIFE category D, n = 19), characteristics decrement (ECSCIFE category B1, n = 2) and performance decrement (ECSCIFE category B2 n = 6). Forty-nine patients underwent ipsilateral explantation/reimplantation. Auditory performance with the second implant was comparable to the first implant levels. The ECSCIFE provides an easy-to-use classification system for international reporting of CI device failures and explantations, however, detailed information of each implant failure may be lost in the final category, however. Cochlear explantation/reimplantation in Melbourne is a safe and effective procedure to restore patients to their pre-operative best auditory function levels.

Endoscopic transnasal intradural repair of anterior skull base cerebrospinal fluid fistulae.

UNLABELLED: This study presents the techniques and results of endoscopic diagnosis and repair of cerebrospinal fluid (CSF) fistulae involving the anterior skull base and paranasal sinuses. DESIGN: A retrospective cohort study of all consecutive patients undergoing endoscopic repair of anterior skull base CSF fistulae. SETTING: Tertiary referral institutions. MATERIALS AND METHODS: Fifty-two patients underwent endoscopic repair of CSF fistula. Thirteen cases were traumatic in origin, 11 spontaneous not associated with meningoencephalocele and 12 with meningoencephalocele. Eleven were iatrogenic and five associated with transphenoidal pituitary surgery, two acute and three delayed following radiotherapy. The average age of patients was 43 and the male to female ratio was 2:1. A variety of techniques were used to repair the dural defect. In the majority of cases placement of a fat plug on the intracranial surface of the dura was performed. RESULTS: Forty-seven of the 52 patients had successful primary endoscopic repair of the CSF fistula and skull base defect. Five patients required a repeat procedure due to early failure of the repair. After an average follow-up of 27 months no patient has had any recurrence of leak giving a primary closure success rate of 90% and secondary closure rate of 100%. CONCLUSIONS: The endoscopic transnasal approach for repair of anterior skull base CSF fistula is a reliable technique and is now the procedure of choice for patients presenting with this problem.

The contour electrode array: safety study and initial patient trials of a new perimodiolar design.

OBJECTIVE: The aim of these studies was to investigate the insertion properties and safety of a new intracochlear perimodiolar electrode array design (Contour). BACKGROUND: An electrode array positioned close to the neural elements could be expected to reduce stimulation thresholds and might potentially reduce channel interaction. METHODS: Two sequential studies were conducted. In study 1, the Contour electrode array was inserted in 12 human temporal bones. After cochlear surface preparation, the position of the array was noted and the basilar membrane was examined for insertion damage. On the basis of the outcome of this temporal bone study, study 2 investigated the Contour array, mounted on a Nucleus CI-24 M device and implanted in three adult patients. RESULTS: Study I showed that in 10 temporal bones, the Contour array was positioned close to the modiolus, and the basilar membrane was intact. In the two remaining bones, the arrays had pierced the basilar membrane and were positioned in the scala vestibuli apical to the penetration. Statistical analysis showed an equivalent probability of insertion-induced damage of the two array designs. In study 2, image analysis indicated that the Contour electrodes were positioned closer to the modiolus than the standard Nucleus straight array. Lower T and C levels, but higher impedance values, were recorded from electrodes close to the modiolus. Initial speech perception data showed that all patients gained useful open-set speech perception, two patients achieving scores of 100% on sentence material 3 months postoperatively. CONCLUSIONS: The temporal bone studies showed the Contour electrode array to be generally positioned closer to the modiolus than the standard Nucleus straight array, and to have an equivalent probability of causing insertion-induced damage.

Surgical implications of perimodiolar cochlear implant electrode design: avoiding intracochlear damage and scala vestibuli insertion.

OBJECTIVE: To review the mechanisms and nature of intracochlear damage associated with cochlear implant electrode array insertion, in particular, the various perimodiolar electrode designs. Make recommendations regarding surgical techniques for the Nucleus Contour electrode to ensure correct position and minimal insertion trauma. BACKGROUND: The potential advantages of increased modiolar proximity of intracochlear multichannel electrode arrays are a reduction in stimulation thresholds, an increase in dynamic range and more localized neural excitation. This may improve speech perception and reduce power consumption. These advantages may be negated if increased intracochlear damage results from the method used to position the electrodes close to the modiolus. METHOD: A review of the University of Melbourne Department of Otolaryngology experience with temporal bone safety studies using the Nucleus standard straight electrode array and a variety of perimodiolar electrode array designs; comparison with temporal bone insertion studies from other centres and postmortem histopathology studies reported in the literature. Review of our initial clinical experience using the Nucleus Contour electrode array. RESULTS: The nature of intracochlear damage resulting from electrode insertion trauma ranges from minor, localized, spiral ligament tear to diffuse organ of Corti disruption and osseous spiral lamina fracture. The type of damage depends on the mechanical characteristics of the electrode array, the stiffness, curvature and size of the electrode in relation to the scala, and the surgical technique. The narrow, flexible, straight arrays are the least traumatic. Pre-curved or stiffer arrays are associated with an incidence of basilar membrane perforation. The cochleostomy must be correctly sited in relation to the round window to ensure scala tympani insertion. A cochleostomy anterior to the round window rather than inferior may lead to scala media or scala vestibuli insertion. CONCLUSION: Proximity of electrodes to the modiolus can be achieved without intracochlear damage provided the electrode array is a free fit within the scala, of appropriate size and shape, and accurate scala tympani insertion is performed.

Susac syndrome: microangiopathy of the retina, cochlea and brain.

BACKGROUND: Susac syndrome is characterized by the triad of branch retinal arterial occlusions, encephalopathy and cochlear microangiopathy. The underlying process is believed to be a small vessel vasculitis causing microinfarcts in the retina, brain and cochlea. METHODS: Analysis of two male and two female cases of Susac syndrome recognized in Australia. RESULTS: In this series the epidemiology, mode of presentation, ophthalmologic features, neurologic and cochleo-vestibular features, radiologic characteristics, cerebrospinal fluid findings, therapeutic interventions, clinical course and outcome of Susac syndrome is examined. Key ophthalmologic differential diagnoses include systemic lupus erythematosis (SLE), Behçet's syndrome and other vasculitides such as sarcoidosis, tuberculosis, syphilis and lymphoma. Neuro-otologic features are most frequently misdiagnosed as multiple sclerosis. CONCLUSION: Susac syndrome, first described in 1979, is becoming an increasingly recognized condition. Early recognition of the syndrome is important because treatment with systemic immunosuppression may minimize permanent cognitive, audiologic and visual sequelae.

Current management of acoustic neuromas: review of surgical approaches and outcomes.

The management options for patients with acoustic neuromas is discussed with a review of 164 patients assessed and treated between 1994 and 1998. Twenty-one patients have neurofibromatosis type II. In 33 cases initial observation was undertaken with repeated imaging. Surgical removal of 122 tumours was performed in 121 patients. Eleven of these patients have NF2, of whom three underwent Auditory Brainstem Implantation. Hearing preservation tumour removal was attempted in 37 and was successful in 20 (54%). The middle cranial fossa approach was used in ten cases with 100% successful hearing preservation. The retrosigmoid approach was used in 27 cases with 36% successful hearing preservation. Non-hearing preservation tumour removal was performed in 85 cases where hearing was poor or the tumour measured more than 2 cm within the cerebellopontine angle. The translabyrinthine approach was used in 80 of these patients. Postoperative facial nerve outcome was dependent on tumour size. All 38 patients with tumours

Multichannel auditory brainstem implantation: the Australian experience.

The multichannel auditory brainstem implant (ABI) provides the potential for hearing restoration in patients with neurofibromatosis type 2 (NF2). Programmes for auditory brainstem implantation have been established in two Australian centres. Eight patients have been implanted under the protocol of an international multi-centre clinical trial. Three patients had ABI insertion at the time of first side tumour removal, four at second side tumour removal and one after previous bilateral surgery where there was some residual tumour. The translabyrinthine approach was used in all cases. Successful positioning of the electrode array was achieved in seven of eight patients, all of whom achieved auditory perception with electrical stimulation. Intra-operative electrically evoked auditory brainstem response testing was successful in four patients and was useful in confirming correct electrode position. In six cases post-operative psychophysical and auditory perception testing demonstrated that useful auditory sensations were achieved. Five of these patients regularly used the implant. In one patient electrode placement was unsuccessful and only non-auditory sensations occurred on stimulation. In the remaining patients non-auditory sensations were minimal and avoidable by selective electrode programming. Auditory brainstem implantation should be considered in patients with NF2. The greatest benefit is seen in patients without debilitating disease who have non-aidable hearing in the contralateral ear.

Serum and urine levels of tamoxifen and its metabolites in patients with advanced breast cancer after a loading dose and at steady-state levels.

PURPOSE: To compare serum and urine levels of tamoxifen and metabolites after a loading dose and at the steady state. METHODS: A loading dose of 160 mg of tamoxifen was given to 14 patients with advanced breast cancer. Thereafter a regular daily dose of 30 mg of tamoxifen was given. Serum and urine levels of tamoxifen and metabolites were measured by high-performance liquid chromatography and compared with levels determined in 31 patients with advanced breast cancer at the steady state at a daily dose of 30 mg of tamoxifen. RESULTS: Serum and urine levels (24-h values) of tamoxifen and metabolites were lower (P < 0.05) after a loading dose than at the steady state. The difference was most pronounced for the metabolites, whereas the tamoxifen loading-dose level was near the steady state. CONCLUSION: Tamoxifen steady state can be reached in 1-2 days by the administration of a loading dose of 160 mg of tamoxifen for 2 days. Tamoxifen metabolite steady-state levels are reached regularly after 4 or more weeks during application of a loading dose. Very little tamoxifen or metabolites are excreted into the urine.

A case of pneumocephalus secondary to VP shunt in a patient with acoustic neuroma.

Pneumocephalus is an uncommon complication of ventriculo-peritoneal (VP) shunts. We present a case of pneumocephalus secondary to a VP shunt in a patient with an acoustic neuroma. The site of the cerebrospinal fluid fistula was found to be into an extensive petrous apex air cell system due to tumour erosion of the internal auditory canal.

Fourth branchial sinus causing recurrent cervical abscess.

BACKGROUND: Three patients who presented with recurrent cervical abscesses were found to have a branchial sinus arising in the piriform fossa. Each patient had previously had cervical abscess drainage procedures. METHODS: A retrospective review of patients with recurrent cervical abscess and associated fourth branchial sinus was carried out. RESULTS: In each case, imaging and endoscopy identified a sinus tract from the left piriform fossa. Neck exploration with hemithyroidectomy and excision of the sinus tract was performed without further recurrence of abscess. CONCLUSIONS: We believe these cases to represent a fourth branchial sinus. The relevant embryology and anatomy of the branchial apparatus is discussed and the pathways for the sinus and fistulous tracts of branchial sinus origin are reviewed. Branchial sinuses are uncommon, but should be considered as the underlying aetiology in patients who present with recurrent cervical abscesses.

Skull osteomyelitis due to Salmonella species: two case reports and review.

Osteomyelitis of the skull is a rare disease. We describe two cases due to Salmonella typhimurium and review 10 previously reported cases of salmonella osteomyelitis of the skull. This infection is frequently complicated by extradural abscess, which may be asymptomatic. Diagnostic imaging by means of computed tomographic scanning with contrast or gadolinium-enhanced magnetic resonance imaging should be performed to detect this complication. A good outcome can be expected with a combination of surgery and antibiotic therapy.