George B. Wanna

Impact of electrode design and surgical approach on scalar location and cochlear implant outcomes

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.

Middle ear implantable hearing devices: an overview.

Hearing loss affects approximately 30 million people in the United States. It has been estimated that only approximately 20% of people with hearing loss significant enough to warrant amplification actually seek assistance for amplification. A significant interest in middle ear implants has emerged over the years to facilitate patients who are noncompliant with conventional hearing aides, do not receive significant benefit from conventional aides, or are not candidates for cochlear implants. From the initial studies in the 1930s, the technology has greatly evolved over the years with a wide array of devices and mechanisms employed in the development of implantable middle ear hearing devices. Currently, these devices are generally available in two broad categories: partially or totally implantable using either piezoelectric or electromagnetic systems. The authors present an up-to-date overview of the major implantable middle ear devices. Although the current devices are largely in their infancy, indications for middle ear implants are ever evolving as promising studies show good results. The totally implantable devices provide the user freedom from the social and practical difficulties of using conventional amplification.

Anatomic verification of a novel method for precise intrascalar localization of cochlear implant electrodes in adult temporal bones using clinically available computed tomography

We have previously described a novel, automated, nonrigid, model‐based method for determining the intrascalar position of cochlear implant (CI) electrode arrays within human temporal bones using clinically available, flat‐panel volume computed tomography (fpVCT). We sought to validate this method by correlating results with anatomic microdissection of CI arrays in cadaveric bones.

Contemporary management of intracranial complications of otitis media.

Objectives: Intracranial complications as a result of otogenic infections occur even in the antibiotic era. Meningitis is the most common reported intracranial complication, followed by brain abscess and lateral sinus thrombosis. The purpose of this study is to review our experience and management of these serious complications. Materials and Methods: A retrospective chart review was performed at a tertiary referral medical center for the period from 1998 to 2007. Charts with acute or chronic otitis media as primary diagnosis were reviewed, and intracranial complications secondary to either were included in the study. Age, sex, clinical presentation, radiographic findings, management, and outcome were studied. Patients with meningitis or petrous apicitis were not included in the study. Results: Ten cases reviewed had intracranial complications. Five patients had brain abscesses, 1 patient had a subdural empyema, and 4 patients had lateral sinus thrombosis. All patients received broad-spectrum intravenous antibiotics for 6 weeks. Mastoidectomy was performed in all patients, but not all patients were treated with direct drainage of the intracranial abscess, especially if clinical and serial radiographic response was favorable. Conclusion: Otogenic intracranial complications can be fatal if not managed appropriately. Broad-spectrum intravenous antibiotics for 6 weeks is usually sufficient treatment. Management of the intracranial disease takes precedence, but direct drainage of the abscess may not be necessary if a patients symptoms, neurologic status, and radiographic findings progress favorably. A high index of suspicion should be maintained on all patients presenting with symptoms not typically seen with routine otitis media.

Assessment of electrode placement and audiological outcomes in bilateral cochlear implantation.

Objective: The goal of this study was to use highly accurate nonrigid algorithms to locate the position of cochlear implant (CI) electrodes and correlate this with audiological performance. Patients: After obtaining institutional review board approval, adult patients who had bilateral CIs were identified, and those with preoperative temporal bone computed tomographic scans were asked to return for a postintervention computed tomography. Sixteen adult patients agreed. Demographics, cause of deafness, length of auditory deprivation, and audiological performance were recorded. Intervention: Using a nonrigid model of the shape variations of intracochlear anatomy, the location of the basilar membrane was specified in relationship to the electrode array. The number of electrodes within each compartment of the cochlea was correlated with hearing in noise and consonant-noun-consonant scores for the known confounding variable: length of deafness. Main Outcomes: Mann-Whitney U tests of differences were used to compare the hearing performance resulting from implants completely in the scala tympani (ST) versus those not completely in the ST. Results: Of all implants, 62.5% were fully inserted in the ST; 34.4% were partially inserted into the ST and 3.1% was fully inserted in the scala vestibuli. Controlling for the known contributing variable of length of auditory deprivation, our results show that the location of electrodes in relationship to the scala is not predictive of audiological performance. Conclusion: We have assessed electrode placement and correlated it with audiological outcome. The presence of the electrodes solely in the ST was not predictive of outcome. We estimate that it would take analyzing data of thousands of CI patients before any valid correlations can be made.

Natural History of Glomus Jugulare: A Review of 16 Tumors Managed with Primary Observation

Objective To characterize clinical disease progression and radiologic growth in a series of observed, previously untreated, glomus jugulare tumors (GJT). Study Design Retrospective review. Setting Tertiary neurotologic referral center. Subjects and Methods All patients with primary GJTs that were observed without intervention for a minimum of 2 years. Primary outcome measures included progression of cranial neuropathy and/or radiologic growth. Results A total of 15 patients (80% female; median age, 69.6 years) with 16 GJTs met inclusion criteria. The most common indications for observation included advanced age (11; 73%) and patient preference (11; 73%). Cranial nerve function remained stable in most subjects over a median clinical follow-up period of 86.4 months. Among the 12 with serial imaging, 5 (42%) GJTs demonstrated radiologic growth, while 7 (58%) remained stable. The median growth rate of the 5 enlarging tumors using the maximum linear dimension was 0.8 mm/y (range, 0.6-1.6 mm/y) or 0.4 cm3/y (0.1-0.9 cm3/y) using volumetric analysis. There were no deaths attributable to tumor progression or treatment. Conclusion In an older subset of patients, we found that a significant number of GJTs do not grow after time of diagnosis and symptoms frequently remain stable for many years. Even with disease progression, most GJTs exhibit indolent growth with slowly progressive cranial neuropathy, affording satisfactory physiologic compensation in most patients. In the absence of brainstem compression or concern for malignancy, observation of GJTs is a viable initial management option for elderly patients.

Percutaneous access to the petrous apex in vitro using customized micro-stereotactic frames based on image-guided surgical technology

Abstract Conclusion. Our study demonstrates (in cadavers) the ability to obtain a minimally invasive approach to access the petrous apex using patient-customized micro-stereotactic frames based on pre-intervention radiographic studies. Objective. To conduct in vitro studies to demonstrate the feasibility of percutaneous petrous apex access using customized, bone-mounted, micro-stereotactic frames. Methods. Cadaveric temporal bone specimens (n = 10) were affixed with three bone-implanted fiducial markers. CT scans were obtained and used in planning, in reference to the fiducial markers, a straight transmastoid infralabyrinthine trajectory from the mastoid surface to the petrous apex without violating the basal turn of the cochlea or the carotid artery. A drill press was mounted on the customized frame and used to guide a 2 mm drill bit on the desired trajectory. The course of the drill bit and its relationship to surrounding vital anatomy (cochlea, carotid artery, facial nerve, and internal jugular vein) were determined by repeat CT scanning. Results. In 10 of 10 specimens, the drill bit trajectory was accurate with clearance (mean ± standard deviation in mm) from the cochlea, facial nerve, carotid artery, and jugular vein of 3.43 ± 1.57, 3.14 ± 1.15, 4.57 ± 1.52, and 6.05 ± 2.98, respectively.

Impact of Intrascalar Electrode Location, Electrode Type, and Angular Insertion Depth on Residual Hearing in Cochlear Implant Patients: Preliminary Results.

Objective To evaluate the relationship between intrascalar electrode location, electrode type (lateral wall, perimodiolar, and midscala), and angular insertion depth on residual hearing in cochlear implant (CI) recipients. Setting Tertiary academic hospital. Patients Adult CI patients with functional preoperative residual hearing with preoperative and postoperative CT scans. Intervention Audiological assessment after CI. Main Outcome Measures Electrode location, angular insertion depth, residual hearing post-CI, and word scores with CI (consonant-nucleus-consonant [CNC]). Results Forty-five implants in 36 patients (9 bilateral) were studied. Thirty-eight electrode arrays (84.4%) were fully inserted in scala tympani (ST), 6 (13.3%) crossed from ST to scala vestibuli (SV), and 1 (2.2%) was completely in SV. Twenty-two of the 38 (57.9%) with full ST insertion maintained residual hearing at 1 month compared with 0 of the 7 (0%) with non-full ST insertion (p = 0.005). Three surgical approaches were used: cochleostomy (C) 6/44, extended round window (ERW) 8/44, and round window (RW) 30/44. C and ERW were small group to compare with RW approaches. However if we combine C + ERW, then RW has higher chance of full ST insertion (p = 0.014). Looking at the full ST group, neither age, sex, nor electrode type demonstrated statistically significant associations with hearing preservation (p = 0.646, p = 0.4, and p = 0.929, respectively). The median angular insertion depth was 429° (range, 373°–512°) with no significant difference between the hearing and nonhearing preserved groups (p = 0.287). Conclusion 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.

Electrode Location and Angular Insertion Depth Are Predictors of Audiologic Outcomes in Cochlear Implantation.

Objectives: 1) Investigate the impact of electrode type and surgical approach on scalar electrode location; and 2) examine the relation between electrode location and postoperative audiologic performance. Setting: Tertiary academic hospital. Patients: Two hundred twenty 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 22.4 (95% CI: 6.3–80.0, p < 0.001) and 55.0 (95% CI: 9.7–312.8, p < 0.001) times more likely to have at least one electrode in the scala vestibuli (SV) compared with lateral wall (LW) electrodes, respectively. Compared with cochleostomy (C), round window (RW) and extended round window (ERW) approaches demonstrated 70% reduction in SV insertion (RW: OR 0.28, 95% CI: 0.1–0.8, p = 0.01; ERW: OR 0.28, 95% CI: 0.1–0.7, p = 0.005). Examining postoperative audiometric performance, consonant-nucleus-consonant (CNC) score increased 0.6% with every 10 degrees increase in angular insertion depth beyond the group minimum of 208 degrees (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 to −0.02, p = 0.02). CNC score decreased 0.3% for every 1 year increase in age (coefficient −0.003, 95% CI: −0.006 to −0.0006, p = 0.02). Conclusions: Electrode design and surgical approach were predictors of scalar electrode location. Specifically, LW electrodes showed higher rates of ST insertion compared with PM or MS. RW and ERW approaches showed higher rates of ST insertion when compared with C. In regards to performance, ST insertion, younger age, and greater angular insertion depth were predictors of improved CNC scores.

Facial nerve outcomes in facial nerve schwannomas.

Objective To better understand the characteristics and outcomes of facial nerve schwannomas (FNSs) over a 30-year period. Study Design Retrospective study. Setting Subspecialty practice at a tertiary hospital. Patients Fifty-six patients diagnosed with FNS over a 30-year period. Methods Preoperative data (audiologic data, facial nerve [FN] function, and patient symptoms), intraoperative data (tumor location, total versus subtotal resection, and FN status), and postoperative data (audiologic data, FN function, and recurrence) were collected. Mann-Whitney and &khgr;2 analyses were done to determine which factors correlated with poor FN outcomes (defined as House-Brackmann ≥4). Results Of the 56 patients in this study, 53 (94.6%) underwent surgical resection of their FNS. Of those patients, 45 (84.9%) underwent total resection, and 8 (15.1%) underwent subtotal resection. Subtotal resection was associated with a statistically significant decreased risk of having postoperative HB grade ≥4 (odds ratio, 0.09; 95% confidence interval, 0.01–0.77; p = 0.028). Of those undergoing a subtotal resection, no patient had further tumor growth seen on postoperative magnetic resonance imaging (average time of last magnetic resonance imaging since operation, 44.9 mo). Tumor location was not statistically associated with poor FN outcome (all p > 0.05). Preoperative FN paralysis was the only preoperative clinical finding statistically associated with poor FN outcomes (p = 0.004). Conclusion We have identified multiple characteristics of FNS as well as multiple factors associated with increased statistical risk of poor FN outcomes.