OBJECTIVE: Human otopathology following drill-out procedures for cochlear implantation (CI) in cases with labyrinthitis ossificans (LO) has not been previously described. This study uses the high sensitivity of histopathology to (1) evaluate surgical drill-out technique with associated intracochlear findings and (2) quantify spiral ganglion neuron populations in a series of patients with LO who underwent CI. STUDY DESIGN: Retrospective otopathology study. SETTING: Otopathology laboratory. SUBJECTS AND METHODS: Temporal bone (TB) specimens from cases with evidence of preoperative intracochlear fibroossification that required a drill-out procedure for CI electrode array insertion were included. All cases were histopathologically evaluated and 3-dimensional reconstructions of the cochleae were performed to interpret drilling paths and electrode trajectories. RESULTS: Five TB specimens were identified, of which 4 underwent drill-out of the basal turn of the cochlea and 1 underwent a radical cochlear drill-out. In multiple TBs, drilling was imprecise with resultant damage to essential structures. Two TBs showed injury to the modiolus, which was associated with substantially decreased or even absent neuronal populations within these areas. In addition, 2 cases with inadequate drill-out or extensive LO of the basal turn resulted in extracochlear placement of electrode arrays into the vestibule due to persistent obstruction within the basal turn. CONCLUSION: Otopathology highlights the challenges of drill-out procedures in cases of LO. Imprecise drilling paths, due to distortion of normal cochlear anatomy, risk injury to the modiolus and adjacent neurons as well as extracochlear placement of electrode arrays, both of which may contribute to poorer hearing outcomes.

OBJECTIVE: Audiometric outcomes following cochlear implantation (CI) in patients with temporal bone fracture (TBF) are variable and the pathophysiology is not well understood. Herein, we describe otopathologic findings in two such cases to provide insight into pathophysiology and outcomes. PATIENTS: Two patients had a history of head trauma resulting in bilateral TBF and sudden, profound, sensorineural hearing loss. INTERVENTION: Both cases underwent unilateral CI following head trauma. MAIN OUTCOME MEASURES: Both TBs from each patient were harvested postmortem and histologically analyzed to determine fracture lines, intralabyrinthine fibroosseous changes, and spiral ganglion neuron (SGN) counts. Clinical histories and audiometric outcomes were also reviewed. RESULTS: In both cases, the implanted TB showed extensive intracochlear ossification, which was greater when fracture involved the cochlea. In contrast, the nonimplanted cochleae were patent with small osseous deposits at the round window membrane. Interaural SGN counts were lower on the implanted side and hearing results were moderate to poor. CONCLUSIONS: Otopathologic analyses of patients with a CI after bilateral TBF are rare. Based on otopathology of two patients with bilateral TBF and subsequent CI, implanted TBs show extensive intracochlear fibroosseous changes greater than the nonimplanted side. Findings have implications for auditory rehabilitation after TBF.

Outcomes following tympanoplasty procedures are variable and depend on the duration, etiology, and location of the perforation as well as the approach for tympanic membrane (TM) grafting (1). Complications following tympanoplasty, including infection, canal stenosis, and lateralization of the graft are known to impact postoperative hearing outcomes (1). “Blunting” is an additional postoperative complication that may compromise the viability and sound conduction properties of the reconstructed TM (1). Blunting occurs when there is loss of the normally acute (45–50 degrees) anterior tympanomeatal angle (ATMA) at the junction between the TM and external auditory canal (EAC) (2).

PURPOSE: Effective operative approaches for the treatment of refractory vertigo in Meniere's disease are invasive. Vestibular neurectomy can preserve hearing and has been shown to be effective; however, current approaches require an extensive craniotomy. Transcanal endoscopic approaches to the internal auditory canal (IAC) with cochlear preservation have been recently described and may offer a minimally invasive approach to selectively sectioning the distal vestibular nerves while preserving residual hearing. MATERIALS AND METHODS: Three cadaveric human heads were imaged using high resolution computed tomography (CT). Anatomic analysis of preoperative CT scans showed adequate diameters ( > 3mm) of the infracochlear surgical corridor for access to the IAC. A transcanal endoscopic approach was attempted to section the vestibular nerve. Post-operative CT scans were assessed to define the operative tract, determine cochlear preservation and assess cochlear and facial nerve preservation. RESULTS: Transcanal endoscopic approach was successfully performed (n=3) using 3mm-diameter, 14cm-length 0 degrees , 30 degrees , and 45 degrees endoscopes and microsurgical drills. In all cases the tympanomeatal flap and ossicular chain remained intact. Internal auditory canalotomy was performed using angled instruments and confirmed in real time via lateral skull base navigation. The vestibular nerves were readily identified and sectioned with preservation of the facial and cochlear nerves. Post-procedure CT showed no violation of the cochlea. CONCLUSION: A transcanal, infracochlear approach to the IAC may permit a minimally invasive approach to distal vestibular neurectomy in cadavers with appropriate anatomy.

HYPOTHESIS: We hypothesize that human cases of cochlear implantation (CI) with folding of the electrode array will demonstrate greater degrees of intracochlear ossification, lower spiral ganglion neuron (SGN) counts, and poorer audiometric outcomes. BACKGROUND: CI electrode array folding, such folding of the proximal array, is a relatively common surgical complication that can occur with forceful electrode insertion and may be an important and avoidable factor affecting implant outcomes. However, otopathologic findings and audiologic outcomes of human cases where folding of the implant electrode array is observed remain undefined. METHODS: Specimens from a human temporal bone repository having undergone CI during life were evaluated. Specimens with folding of the electrode array on histological analysis constituted study cases. Electrode-matched specimens without array folding constituted controls. All specimens were examined by light microscopy and histopathologically described. Intracochlear fibrosis and osseous tissue, and SGN counts were measured. Pre- and postoperative word recognition scores were also compared. RESULTS: Cases with folded electrodes showed greater volumes of intracochlear osseous tissue than controls, which was most prominent in areas adjacent to array folding. Both cases and controls demonstrated similar amounts of fibrous tissue. Folded cases showed decreased SGNs when compared with the contralateral ear, whereas controls showed stable SGN populations between ears. In this small cohort, postoperative hearing outcomes were similar between groups. CONCLUSION: Atypical fibro-osseous changes and lower SGN counts are observed in cases of CI electrode folding. Future studies are necessary to determine if recognition and correction of folding can prevent long-term intracochlear changes.

Objective: This study aims to define a reliable protocol for radiographic identification of placement and tip foldover of newly designed precurved and straight electrodes. Study Design: Prospective imaging study. Setting: Academic institution. Methods: Three models of cochlear implants (Cochlear, MED-EL, and Advanced Bionics) were inserted into fresh cadaveric specimens (n = 2) in 3 configurations (normal positioning in the scala tympani, intracochlear tip foldover, and placement into the vestibular system) for a total of 9 implant scenarios. Specimens were imaged with plain radiography in Stenvers projection, as well as by high-resolution computed tomography. Results: Electrode placement and presence or absence of electrode tip foldover were easily identified in all 9 scenarios on plain radiography based on the described technique. Each was confirmed with high-resolution computed tomography. Plain film temporal bone images of new electrode designs with proper and improper placement are provided for reference. Conclusion: A defined protocol for intraoperative plain film radiography allowed for reliable imaging of 3 newly designed cochlear implant electrodes and immediate identification of extracochlear placement and tip foldover. Findings may be used for intraoperative confirmation of electrode array placement.