Objectives/Hypothesis Three surgical approaches: cochleostomy (C), round window (RW), and extended round window (ERW); and two electrodes types: lateral wall (LW) and perimodiolar (PM), account for the vast majority of cochlear implantations. The goal of this study was to analyze the relationship between surgical approach and electrode type with final intracochlear position of the electrode array and subsequent hearing outcomes. Study Design Comparative longitudinal study. Methods One hundred postlingually implanted adult patients were enrolled in the study. From the postoperative scan, intracochlear electrode location was determined and using rigid registration, transformed back to the preoperative computed tomography which had intracochlear anatomy (scala tympani and scala vestibuli) specified using a statistical shape model based on 10 microCT scans of human cadaveric cochleae. Likelihood ratio chi-square statistics were used to evaluate for differences in electrode placement with respect to surgical approach (C, RW, ERW) and type of electrode (LW, PM). Results Electrode placement completely within the scala tympani (ST) was more common for LW than were PM designs (89% vs. 58%; P < 0.001). RW and ERW approaches were associated with lower rates of electrode placement outside the ST than was the cochleostomy approach (9%, 16%, and 63%, respectively; P < 0.001). This pattern held true regardless of whether the implant was LW or PM. When examining electrode placement and hearing outcome, those with electrode residing completely within the ST had better consonant-nucleus-consonant word scores than did patients with any number of electrodes located outside the ST (P = 0.045). Conclusion These data suggest that RW and ERW approaches and LW electrodes are associated with an increased likelihood of successful ST placement. Furthermore, electrode position entirely within the ST confers superior audiological outcomes. Level Of Evidence 2b.

Objectives-1) Investigate the impact of electrode type and surgical approach on scalar electrode location in a large patient cohort; and 2) examine the relation between electrode location and postoperative audiologic performance. Setting-Tertiary academic hospital. Patients-220 post-lingually deafened adults undergoing cochlear implant (CI).Main Outcome Measures-Primary outcome measures of interest were scalar electrode location and postoperative audiologic performance.Results-In 68% of implants, electrodes were observed to be located solely in the scala tympani (ST). Multivariate analysis demonstrated perimodiolar(PM) and Mid-scala(MS) electrodes were p<0.001) times more likely to have at least one electrode in the scala vestibuli (SV) compared to lateral wall(LW) electrodes, respectively. Compared to cochleostomy(C), round window(RW) and extended round window(ERW) approaches demonstrated 70% reduction in SV insertion (OR 0.28,95%CI:0.1-0.8, p=0.01; ERW (OR O.28,95%CI:0.1-0.7, p=0.005). Examining postoperative audiometric performance, CNC score increased 0.6% with every 10° increase in angular insertion depth beyond the group minimum of 208° (Coefficient 0.0006,95%CI:0.0001-0.001, p=0.03). SV insertion was associated with a 12% decrease in CNC score (Coefficient -0.12,95%CI:-0.22--0.02, p=0.02). CNC score decreased 0.3% for every 1 year increase in age (Coefficient -0.003,95%CI:-0.006--0.0006), p=0.02). HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptConclusions-Electrode design and surgical approach were predictors of scalar electrode location. Specifically, LW electrodes showed higher rates of ST insertion compared to PM or MS. RW and ERW approaches showed higher rates of ST insertion when compared to C. In regards to performance, ST insertion, younger age, and greater angular insertion depth were predictors of improved CNC scores.

Object The goals of this study were to report the clinical presentation, radiographic findings, operative strategy, and outcomes among patients with temporal bone encephaloceles and cerebrospinal fluid fistulas (CSFFs) and to identify clinical variables associated with surgical outcome. Methods A retrospective case series including all patients who underwent a middle fossa craniotomy or combined mastoid–middle cranial fossa repair of encephalocele and/or CSFF between 2000 and 2012 was accrued from 2 tertiary academic referral centers. Results Eighty-nine consecutive surgeries (86 patients, 59.3% women) were included. The mean age at time of surgery was 52.3 years, and the left side was affected in 53.9% of cases. The mean delay between symptom onset and diagnosis was 35.4 months, and the most common presenting symptoms were hearing loss (92.1%) and persistent ipsilateral otorrhea (73.0%). Few reported a history of intracranial infection (6.7%) or seizures (2.2%). Thirteen (14.6%) of 89 cases had a history of major head trauma, 23 (25.8%) were associated with chronic ear disease without prior operation, 17 (19.1%) occurred following tympanomastoidectomy, and 1 (1.1%) developed in a patient with a cerebral aqueduct cyst resulting in obstructive hydrocephalus. The remaining 35 cases (39.3%) were considered spontaneous. Among all patients, the mean body mass index (BMI) was 35.3 kg/m2, and 46.4% exhibited empty sella syndrome. Patients with spontaneous lesions were statistically significantly older (p = 0.007) and were more commonly female (p = 0.048) compared with those with nonspontaneous pathology. Additionally, those with spontaneous lesions had a greater BMI than those with nonspontaneous disease (p = 0.102), although this difference did not achieve statistical significance. Thirty-two surgeries (36.0%) involved a middle fossa craniotomy alone, whereas 57 (64.0%) involved a combined mastoid–middle fossa repair. There were 7 recurrences (7.9%); 2 patients with recurrence developed meningitis. The use of artificial titanium mesh was statistically associated with the development of recurrent CSFF (p = 0.004), postoperative wound infection (p = 0.039), and meningitis (p = 0.014). Also notable, 6 of the 7 cases with recurrence had evidence of intracranial hypertension. When the 11 cases that involved using titanium mesh were excluded, 96.2% of patients whose lesions were reconstructed with an autologous multilayer repair had neither recurrent CSFF nor meningitis at the last follow-up. Conclusions Patients with temporal bone encephalocele and CSFF commonly present with persistent otorrhea and conductive hearing loss mimicking chronic middle ear disease, which likely contributes to a delay in diagnosis. There is a high prevalence of obesity among this patient population, which may play a role in the pathogenesis of primary and recurrent disease. A middle fossa craniotomy or a combined mastoid–middle fossa approach incorporating a multilayer autologous tissue technique is a safe and reliable method of repair that may be particularly useful for large or multifocal defects. Defect reconstruction using artificial titanium mesh should generally be avoided given increased risks of recurrence and postoperative meningitis.

Objectives 1) Examine angular insertion depths (AID) and scalar location of MED-EL electrodes; and 2) determine the relationship between angular insertion depth (AID) and audiologic outcomes controlling for scalar position. Study Design Retrospective review. Methods Post-lingually deafened adults undergoing cochlear implantation with Flex 24, Flex 28, and Standard electrode arrays were identified. Patients with preoperative and postoperative CT scans were included, such that electrode location and AID could be determined. Outcome measures were 1) speech perception in the CI-only condition and 2) short-term hearing preservation. Results Forty-eight implants were included; all electrodes (48/48) were positioned entirely within the scala tympani. The median AID was 408°(IQ range 373-449°) for Flex 24, 575°(IQ range 465-584°) for Flex 28, and 584°(IQ range 368-643°) for Standard electrodes. The mean postoperative CNC score was 43.7%±21.9. A positive correlation was observed between greater AID and better CNC performance (r=0.48, p<0.001). Excluding patients with post-operative residual hearing, a strong correlation between AID and CNC persisted (r=0.57, p<0.001). In patients with pre-operative residual hearing, mean low-frequency PTA shift was 27 dB ± 14. A correlation between AID and low-frequency PTA shift at activation was noted (r=0.41, p=0.04). Conclusions Favorable rates of scala tympani insertion (100%) were observed. In the CI only condition, a direct correlation between greater AID and CNC score was noted regardless of post-operative hearing status. Deeper insertions were, however, associated with worse short-term hearing preservation. When patients without post-operative residual hearing were analyzed independently, the relationship between greater insertion depth and better performance was strengthened.

Scalar excursion is a strong predictor of losing residual hearing. However, neither age, sex, electrode type, nor angular insertion depth was correlated with hearing preservation in the full ST group. Techniques to decrease the risk of electrode excursion from ST are likely to result in improved residual hearing and CI performance.

Objective To describe the incidence, clinical presentation, and performance of cochlear implant (CI) recipients with tip fold-over. Study design Retrospective case series. Setting Tertiary referral center. Patients CI recipients who underwent postoperative CT scanning. Intervention(s) Tip fold-over was identified tomographically using previously-validated software that identifies the electrode array. Electrophysiologic testing including spread of excitation (SOE) or electric field imaging (EFI) was measured on those with fold-over. Main outcome measure(s) Location of the fold-over; audiological performance pre and post selective deactivation of fold-over electrodes. Results 303 ears of 235 CI recipients had postoperative CTs available for review. Six (1.98%) had tip fold-over with 5/6 right-sided ears. Tip fold-over occurred predominantly at 270° and was associated with pre-curved electrodes (5/6). Patients did not report audiological complaints during initial activation. In one patient, the electrode array remained within the scala tympani with preserved residual hearing despite the fold-over. SOE supported tip fold-over, but the predictive value was not clear. EFI predicted location of the fold-over with clear predictive value in one patient. At an average follow-up of 11 months, three subjects underwent deactivation of the overlapping electrodes with two of them showing marked audiological improvement. Conclusions In a large academic center with experienced surgeons, tip fold-over occurred at a rate of 1.98% but was not immediately identifiable clinically. CT imaging definitively showed tip fold-over. Deactivating involved electrodes may improve performance possibly avoiding revision surgery. EFI may be highly predictive of tip fold-over and can be run intraoperatively, potentially obviating the need for intra-op fluoroscopy.

ObjectivesAs indications for cochlear implantation have expanded to include patients with more residual hearing, increasing emphasis has been placed on minimally traumatic electrode insertion. Histopathologic evaluation remains the gold standard for evaluation of cochlear trauma, but advances in imaging techniques have allowed clinicians to determine scalar electrode location in vivo. This review will examine the relationship between scalar location of electrode arrays and audiologic outcomes. In addition, the impact that surgical approach, electrode design, and insertion depth have on scalar location will be evaluated. Data Sources: PubMed literature review Review Methods: A review of the current literature was conducted to analyze the relationship between scalar location of cochlear implant electrode arrays and speech perception outcomes. Further, data were reviewed to determine the impact that surgical variables have on scalar electrode location.ResultsElectrode insertions into the scala tympani are associated with superior speech perception and higher rates of hearing preservation. Lateral wall electrodes, and round window/extended round window approaches appear to maximize the likelihood of a scala tympani insertion. It does not appear that deeper insertions are associated with higher rates of scalar translocation.ConclusionSuperior audiologic outcomes are observed for electrode arrays inserted entirely within the scala tympani. The majority of clinical data demonstrate that lateral wall design and a round window approach increase the likelihood of a scala tympani insertion.Level of EvidenceN/A.

Objective To characterize the risk and predictors of growth during observation of vestibular schwannomas (VS). Study Design Retrospective case series. Setting Single academic, tertiary care center. Patients 564 consecutive VS patients who underwent at least two MRI studies prior to intervention. Intervention(s) Serial MRI studies Main outcome measure(s) Tumor growth, defined as a ≥2 mm increase in the maximum tumor diameter between consecutive MRI studies, or between the first and last study. Results A total of 1,296 patients (1995–2015) with VS were identified. Of those, 564 patients (median age 59.2 years; 53.5% female) were initially observed and underwent multiple MRI studies (median follow-up 22.9 months, interquartile range [IQR] 11.7 – 42.7). The median maximum tumor diameter at presentation was 1.00 cm (IQR 0.6 – 1.51 cm). In all, 40.8% of tumors demonstrated growth and 32.1% underwent intervention (21.5% microsurgery, 10.5% radiation) during the surveillance period. Multivariable Cox regression analysis showed that for each tumor, the risk of growth or intervention was significantly increased for larger initial VS diameters (HR=2.22; 95% CI: 1.90 – 2.61) and when disequilibrium was a presenting symptom (HR=1.70; 95% CI: 1.30 – 2.23). Patient age, gender, aspirin use and presenting symptoms of asymmetric hearing loss, tinnitus, and vertigo, were not associated with tumor growth. Conclusions To date, this is the largest series of observed VS reported in the literature. Risk of VS growth is significantly increased among patients who present with larger tumors and who have concomitant disequilibrium. IRB 151481 Define Professional Practice Gap & Educational Need No cohort with this sample size has assessed vestibular schwannoma growth rates in conjunction with this number of variables. Learning Objective To characterize vestibular schwannoma growth rates and predictors of growth.