Detection of Extracochlear Electrodes Using Stimulation-Current- Induced Non-Stimulating Electrode Voltage Recordings With Different Electrode Designs.

HYPOTHESIS: Stimulation-Current-Induced Non-Stimulating Electrode Voltage Recordings (SCINSEVs) can help detect extracochlear electrodes for a variety of Cochlear Implant (CI) devices. BACKGROUND: Extracochlear electrodes (EEs) occur in 9 to 13% of cochlear implantations and commonly go unnoticed without imaging. Electrodes on the electrode array located extracochlearly are associated with non-auditory stimulation and a decrease in speech outcomes. We have previously shown that SCINSEVs, with hardware and software from one manufacturer, could detect EEs. Here, we test the generalizability to other manufacturers. METHODS: Fresh-frozen human cadaveric heads were implanted with Cochlear Ltd. CI522 (CI-A) and MED-EL's FLEX24 (CI-B) electrodes. Contact impedances and SCIN- SEVs were measured, with Cochlear Ltd. research Custom Sound software (Transimpedance Matrix) and MED-EL's clinical MAESTRO (Impedance Field Telemetry), for full insertion and EEs in air, saline and soft tissue. An automated detection tool was optimized and tested for these implants. Intra-operative SCINSEVs with EEs were collected for clinical purposes for six patients. RESULTS: The pattern of SCINSEVs changed in the transition zone from intracochlear to extracochlear electrodes, even with low contact impedances on EEs. Automated detection in the cadaveric specimens, with two or more EEs in saline or soft tissue, showed a mean 91% sensitivity and specificity for CI-A and 100% sensitivity and specificity for CI-B. Quantification of EEs showed significant correlations of r  = 0.69 between estimated and actual EEs for CI-A and r = 0.76 for CI-B. CONCLUSION: The applicability of SCINSEVs to detect extra- cochlear electrodes could be expanded to other cochlear implant companies despite differences in electrode array design and measurement software.

Cochlear Implantation in Elderly Patients: Survival Duration, Hearing Outcomes, Complication Rates, and Cost Utility.

INTRODUCTION: The prevalence of hearing loss and its consequences is increasing as the elderly population grows. As the guidelines for cochlear implantation (CI) expand, the number of elderly CI recipients is also increasing. We report complication rates, survival duration, and audiological outcomes for CI recipients aged 80 years and over and discuss the cost utility of CI in this age group. METHODS: A retrospective cohort study was undertaken of all CI recipients (126 cases), aged 80 years and over at the time of their surgery, implanted at our institution (Cambridge University Hospitals) during a period from January 1, 2001, to March 31, 2019. Data on survival at 1, 3, and 5 years post-implantation, post-operative complications and functional hearing outcomes including audiometric and speech discrimination outcomes (Bamford-Kowal-Bench sentence test) have been reported. RESULTS: The mean age at implantation was 84 years. The mean audiometric score improved from 108 dB HL to 28 dB HL post-implantation. The mean Bamford-Kowal-Bench score improved from 14% to 66% and 73% at 2 and 12 months post-implantation, respectively. The complication rate was 15.3%. The survival probability at 1 year post-implantation was 0.95 for females and 0.93 for males, at 3 years was 0.89 for females and 0.81 for males, and at 5 years was 0.74 for females and 0.54 for males. CONCLUSION: CI is safe and well-tolerated in this age group and elderly patients gain similar audiometric and functional benefit as found for younger age groups.

Pain After Cochlear Implantation Without Signs of Inflammation: A Systematic Review.

OBJECTIVES: This review summarizes current evidence on causes and management strategies for delayed pain post-cochlear implantation (CI) surgery, without clinical evidence of inflammation or infection. METHODS: The systematic review was undertaken in line with Preferred Reporting Items for Systematic review and Meta-Analysis Protocols 2015 guidelines. A literature search was undertaken, with inclusion of patients who underwent CI and presented with delayed pain (>3 months post-operatively) around their device site without an identifiable cause. Analysis was undertaken using MATLAB (MathWorks, Natick, MA) and the R-software package (www.r-project.org). RESULTS: 4 articles (48 patients), all retrospective case series, met inclusion criteria. The mean onset of pain post-CI was 60 months and mean follow-up was 15.8 months, there was no difference in the prevalence of pain between device brands (p=0.13). The majority (90%) did not have any hearing deterioration, and investigations did not reveal a cause for the pain in any of the patients. In terms of management, medical therapies, including oral therapy (analgesia, non-steroidal anti-inflammatories, antibiotics) and local treatments (topical, injections) resolved pain in 41% and 63%, respectively. Surgical intervention (explantation, magnet replacement, tympanic neurectomy), where undertaken, resolved pain in 100%. A minority had an identifiable infective microorganism cultured from intra-operative soft tissue or biofilm samples. CONCLUSIONS: Evidence for the causes and management of delayed pain post-CI without clinical evidence of inflammation is scarce. A stepwise approach is deemed best, with decisions being made on an individual basis, evaluating each patient's specific circumstances and priorities. Further evaluation of explanted devices would allow for better understanding of the causes and treatment of this group of patients.

Hearing rehabilitation outcomes in cochlear implant recipients with vestibular schwannoma in observation or radiotherapy groups: A systematic review.

Objectives: Vestibular schwannomas (VS) are rare benign tumours of the vestibular nerve that cause hearing loss. Management strategies include watchful waiting, radiotherapy or surgical resection. Historically, the presence of retrocochlear disease has been considered to be a contra-indication to cochlear implantation (CI). The aim of this systematic review is to assess hearing rehabilitation outcomes for CI recipients with VS, either sporadic or associated with neurofibromatosis type 2, whose tumours have been managed with either observation or radiotherapy.Methods: PubMed, Embase, and Cochrane Library databases were searched from inception through to November 2018. 50 cases from 12 studies met the inclusion criteria. Patient demographics, VS characteristics, management strategy, pre-CI hearing status, electrical promontory stimulation testing, post-CI hearing status and speech perception scores, functional benefits and follow-up length are reported.Results: Radiotherapy and observation groups had similar patient demographics in terms of age at CI, tumour size and duration of deafness. Following CI, 64% and 60% of patients in the radiotherapy and observation groups achieved open-set speech perception, respectively. Pure tone average thresholds (33 vs. 39 dB) and speech scores were also comparable between both groups.Conclusion: Ipsilateral CI in patients with VS that have not been surgically resected can provide beneficial hearing rehabilitation outcomes.

Potts puffy tumour: a rare but important diagnosis.

Potts puffy tumour (PPT) is a subperiosteal abscess arising from frontal bone osteomyelitis. We present a case of a 75-year-old lady with headache and a forehead swelling who was initially treated for sinusitis and giant cell arteritis in a primary care setting, but failed to improve. Following clinical deterioration and further investigation, CT appearances were consistent with a diagnosis of PPT and an extra-axial collection. Needle decompression, frontal trephine and endoscopic frontal sinusotomy were performed and intraoperative swabs cultured Streptococcus constellatus PPT is an unusual clinical entity that benefits from prompt antibiotic and surgical management, and therefore early recognition is paramount. We highlight that PPT should be a differential diagnosis in all patients presenting with forehead or frontal swelling. Use of radiological imaging (CT/MRI) is necessary to not only confirm a diagnosis of PPT but to identify further intracranial complications, which can be life-threatening.

Behavioural benefits of multisensory processing in ferrets.

Enhanced detection and discrimination, along with faster reaction times, are the most typical behavioural manifestations of the brain's capacity to integrate multisensory signals arising from the same object. In this study, we examined whether multisensory behavioural gains are observable across different components of the localization response that are potentially under the command of distinct brain regions. We measured the ability of ferrets to localize unisensory (auditory or visual) and spatiotemporally coincident auditory-visual stimuli of different durations that were presented from one of seven locations spanning the frontal hemifield. During the localization task, we recorded the head movements made following stimulus presentation, as a metric for assessing the initial orienting response of the ferrets, as well as the subsequent choice of which target location to approach to receive a reward. Head-orienting responses to auditory-visual stimuli were more accurate and faster than those made to visual but not auditory targets, suggesting that these movements were guided principally by sound alone. In contrast, approach-to-target localization responses were more accurate and faster to spatially congruent auditory-visual stimuli throughout the frontal hemifield than to either visual or auditory stimuli alone. Race model inequality analysis of head-orienting reaction times and approach-to-target response times indicates that different processes, probability summation and neural integration, respectively, are likely to be responsible for the effects of multisensory stimulation on these two measures of localization behaviour.