Intraoperative Transcranial Motor-Evoked Potential Monitoring of the Facial Nerve during Cerebellopontine Angle Tumor Resection

Objective To determine whether transcranial motor-evoked potential (TCMEP) monitoring of the facial nerve (FN) during cerebellopontine angle (CPA) tumor resection can predict both immediate and long-term postoperative FN function. Design Retrospective review. Setting Tertiary referral center. Main Outcome Measures DeltaTCMEP (final-initial) and immediate and long-term facial nerve function using House Brackmann (HB) rating scale. Results Intraoperative TCMEP data and immediate and follow-up FN outcome are reported for 52 patients undergoing CPA tumor resection. Patients with unsatisfactory facial outcome (HB >2) at follow-up had an average deltaTCMEP of 57 V, whereas those with HB I or II had a mean deltaTCMEP of 0.04 V (t = -2.6, p < 0.05.) Intraoperative deltaTCMEP did not differ significantly between groups with satisfactory (HB I, II) and unsatisfactory (HB > 2) facial function in the immediate postoperative period. Conclusion Intraoperative TCMEP of the facial nerve can be a valuable adjunct to conventional facial nerve electromyography during resection of tumors at the CPA. Intraoperative deltaTCMEP >57 V may be worrisome for long-term recovery of satisfactory facial nerve function.

Revision cochlear implantation following internal auditory canal insertion

OBJECTIVES/HYPOTHESIS

In pediatric patients with congenital malformations of the inner ear, anomalies within the anatomy may facilitate unintentional insertion of the cochlear implant electrode into the internal auditory canal. Revision procedures for removal and replacement of cochlear implant electrodes following internal auditory canal insertion are fraught with potential danger, including the theoretical risk of injury to vasculature within the internal auditory canal, repeat insertion within the internal auditory canal, and cerebrospinal fluid leak. The objective of this presentation is to describe a technique for revision cochlear implantation following internal auditory canal insertion to minimize the potential associated risks.

STUDY DESIGN

Case series.

METHODS

A retrospective chart review was performed on all patients at a tertiary care facility who underwent revision cochlear implantation for internal auditory canal insertion between January 1999 and July 2011.

RESULTS

A total of four patients referred from outside institutions have undergone revision cochlear implantation for internal auditory canal insertion. The records from these patients were reviewed. Electrodes were safely removed in all cases without injury to the anterior inferior cerebellar artery or its branches (i.e., labyrinthine artery). Complete insertion was accomplished on reimplantation. Neural response telemetry was performed in all cases, and responses were noted. Fluoroscopy was utilized to visualize electrode progression during insertion. A detailed description of the operative technique is provided.

CONCLUSIONS

This case series describes a technique for revision cochlear implantation that appears to be safe and effective in preventing potential associated complications.

Hearing Loss 2013: Expanded Technology, Expanded Criteria

Program Description:

The purpose of this course is to educate our otolaryngology community about how best to provide the widest array of surgical technologies to the largest populations of patients with hearing loss. Traditionally, technologic advancement has driven the field forward, though recent attention has also focused on expanding eligibility criteria for existing technology. The format will be a panel of experts with proposed topics organized by patient population (rather than by technology), including patients with moderate to severe hearing loss and significant residual hearing, single sided-deafness, tinnitus, children, age extremes, the multi-handicapped, cochlear nerve deficiency, and others.

Educational Objectives:

1) Recognize the most current surgical technologies available to patients with hearing loss. 2) Articulate the rationale for expanding inclusion criteria for existing technologies to patients previously considered ineligible. 3) Evaluate how promising preliminary outcomes data support the continued expansion of both technology and criteria for patients with hearing loss.

Real-time measurement of electrode impedance during intracochlear electrode insertion

OBJECTIVES/HYPOTHESIS

This pilot study details the use of a software tool that uses continuous impedance measurement during electrode insertion, with the eventual potential to assess and optimize electrode position and reduce insertional trauma.

STUDY DESIGN

Software development and experimental study with human cadaveric cochleae and two live surgeries.

METHODS

A prototype program to measure intracochlear electrode impedance and display it graphically in real time has been developed. The software was evaluated in human cadaveric temporal bones while simultaneously making real-time fluoroscopic recordings and in two live surgeries during intracochlear electrode insertion.

RESULTS

Impedance changes were observed with various scalar positions, and values were consistent with those obtained using clinically available software. Using Contour Advance electrodes, impedance values increased after stylet removal, particularly when using the monopolar mode.

CONCLUSIONS

Impedance values seem systematically affected by electrode position, with higher values being associated with proximity to the cochlear wall. The new software is capable of acquiring impedance measurements during electrode insertion, and these data may be useful to guide surgeons to achieve optimal and atraumatic electrode insertion, to guide robotic electrode insertion, and to provide insights about electrode position in the cochlea.

Outcomes of Direct Facial-to-Hypoglossal Neurorrhaphy with Parotid Release

Lesions of the temporal bone and cerebellopontine angle and their management can result in facial nerve paralysis. When the nerve deficit is not amenable to primary end-to-end repair or interpositional grafting, nerve transposition can be used to accomplish the goals of restoring facial tone, symmetry, and voluntary movement. The most widely used nerve transposition is the hypoglossal-facial nerve anastamosis, of which there are several technical variations. Previously we described a technique of single end-to-side anastamosis using intratemporal facial nerve mobilization and parotid release. This study further characterizes the results of this technique with a larger patient cohort and longer-term follow-up. The design of this study is a retrospective chart review and the setting is an academic tertiary care referral center. Twenty-one patients with facial nerve paralysis from proximal nerve injury at the cerebellopontine angle underwent facial-hypoglossal neurorraphy with parotid release. Outcomes were assessed using the Repaired Facial Nerve Recovery Scale, questionnaires, and patient photographs. Of the 21 patients, 18 were successfully reinnervated to a score of a B or C on the recovery scale, which equates to good oral and ocular sphincter closure with minimal mass movement. The mean duration of paralysis between injury and repair was 12.1 months (range 0 to 36 months) with a mean follow-up of 55 months. There were no cases of hemiglossal atrophy, paralysis, or subjective dysfunction. Direct facial-hypoglossal neurorrhaphy with parotid release achieved a functional reinnervation and good clinical outcome in the majority of patients, with minimal lingual morbidity. This technique is a viable option for facial reanimation and should be strongly considered as a surgical option for the paralyzed face.

Phase II trial of lapatinib in adult and pediatric patients with neurofibromatosis type 2 and progressive vestibular schwannomas

This single-institution phase II study was performed to estimate the response rate to lapatinib in neurofibromatosis type 2 (NF2) patients with progressive vestibular schwannoma (VS). Twenty-one eligible patients were enrolled. Brain and spine MRIs, including 3-dimensional volumetric tumor analysis, and audiograms were performed once at baseline and again every 12 weeks. The primary response end point was evaluable in 17 patients and defined as ≥15% decrease in VS volume. Hearing was evaluable as a secondary end point in 13 patients, with responses defined as an improvement in the pure tone average of at least 10 dB  or a statistically significant increase in word recognition scores. Four of 17 evaluable patients experienced an objective volumetric response (23.5%; 95% confidence interval [CI], 10%-47%), with median time to response of 4.5 months (range, 3-12). In responders, reduction in VS volumes ranged from -15.7% to -23.9%. Four of 13 patients evaluable for hearing met hearing criteria for response (30.8%; 95% CI, 13%-58%). One sustained response exceeded 9 months in duration. Median time to overall progression (ie, volumetric progression or hearing loss) was 14 months. The estimated overall progression-free survival and volumetric progression-free survival at 12 months were 64.2% (95% CI, 36.9%-82.1%) and 70.6% (95% CI, 43.1%-86.6%), respectively. Toxicity was generally minor, and no permanent dose modifications were required. Lapatinib carries minor toxicity and has objective activity in NF2 patients with progressive VS, including volumetric and hearing responses. Future studies could explore combination therapy with other molecular targeted agents such as bevacizumab.

Flat-panel computed tomography versus multislice computed tomography to evaluate cochlear implant positioning

OBJECTIVE

To evaluate and compare image quality between flat-panel volumetric computed tomography (fpVCT) and multislice CT (msCT) in temporal bones with cochlear implants (CIs), and to evaluate fpVCT imaging for accuracy in determining CI electrode positioning.

METHODS

Six cadaveric temporal bones were imaged prior to CI using fpVCT. Each bone was implanted with an electrode array and rescanned in order to create radial reformatted images through each electrode contact. Electrode-modiolar interval (EMI) distances were measured. The bones were fixed and cut in order to grossly evaluate for CI intrascalar positioning and insertional trauma.

MAIN OUTCOME MEASURE

To compare image quality between fpVCT and msCT in temporal bones with CI, and to evaluate the utility of fpVCT in post-implantation temporal bone analysis.

RESULTS

The mean EMI distances did not differ significantly between fpVCT and msCT images, while the image quality was significantly better for fpVCT. Furthermore, information about intracochlear trauma and intrascalar electrode array positioning can be ascertained using this radiographic technique.

CONCLUSION

fpVCT and msCT do not differ significantly in the evaluation of EMI distances in implanted temporal bones, but the image quality is significantly better using fpVCT. Additionally, useful information regarding intracochlear trauma, electrode depth of insertion, and intrascalar positioning can be gained from fpVCT imaging. Given the ease of use, superior image quality, improved convenience, reduced levels of radiation, and agreement with histology, fpVCT is a valuable option for post-implantation temporal bone imaging.

Pediatric cochlear implantation: candidacy evaluation, medical and surgical considerations, and expanding criteria

Since the first cochlear implant approved by the US Food and Drug Administration in the early 1980s, great advances have occurred in cochlear implant technology. With these advances, patient selection, preoperative evaluation, and rehabilitation consideration continue to evolve. This article describes the current practice in pediatric candidacy evaluation, reviews the medical and surgical considerations in pediatric cochlear implantation, and explores the expanding criteria for cochlear implantation within the pediatric population.

Implantation of the common cavity malformation may prevent meningitis

OBJECTIVES AND IMPORTANCE: Children with certain congenital malformations of the inner ear, including those with a common cavity defect, have a higher incidence of spontaneous cerebrospinal fluid (CSF) leak and resulting meningitis. However, they may also benefit from cochlear implantation. We suggest that surgical management may be possible that both prevents meningitis and provides hearing rehabilitation during the same procedure.

CLINICAL PRESENTATION

A 2-year-old girl with bilateral common cavity defects who had previously undergone cochlear implantation developed contralateral CSF leak resulting in meningitis.

INTERVENTION

After resolution of the infection, cochlear implantation was performed at the same time as definitive CSF leak repair. Simultaneous cochlear implantation and repair of the CSF leak successfully decreased the chance of recurrent meningitis in this case. She has been deriving hearing benefit from the bilateral implants.

CONCLUSION

This case suggests a role for cochlear implantation to be combined with simultaneous CSF leak repair in children with a cochlear malformation. Furthermore, bilateral cochlear implantation at an early age may be warranted in these patients before CSF leaks and meningitis have occurred.

Cochlear implantation in prelingually deafened adolescents

OBJECTIVES

To determine the efficacy of cochlear implantation (CI) in prelingually deafened adolescent children and to evaluate predictive variables for successful outcomes.

DESIGN

Retrospective medical record review.

PARTICIPANTS

Children aged 10 to 17 years with prelingual hearing loss (mean length of deafness, 11.5 years) who received a unilateral CI (mean age at CI, 12.9 years).

INTERVENTION

Unilateral CI.

MAIN OUTCOME MEASURES

Standard speech perception testing (Consonant-Nucleus-Consonant [CNC] monosyllabic word test and Hearing in Noise [HINT] sentence test) was performed preoperatively, 1 year postoperatively (year 1), and at the last follow-up/end of the study (EOS).

RESULTS

There was a highly significant improvement in speech perception scores for both HINT sentence and CNC word testing from the preoperative testing to year 1 (mean change score, 51.10% and 32.23%, respectively; P < .001) and from the preoperative testing to EOS (mean change score, 60.02% and 38.73%, respectively; P < .001), with a significantly greater increase during the first year (P < .001). In addition, there was a highly significant correlation between improvements in performance scores on the CNC word and HINT sentence speech perception tests and both age at CI and length of deafness at the year 1 testing (P ≤.009) but not from the year 1 testing to EOS testing. Adolescents with progressive deafness and those using oral communication before CI performed significantly better than age-matched peers.

CONCLUSIONS

Adolescents with prelingual deafness undergoing unilateral CI show significant improvement in objective hearing outcome measures. Patients with shorter lengths of deafness and earlier age at CI tend to outperform their peers. In addition, patients with progressive deafness and those using oral communication have significantly better objective outcomes than their peers.

Development and evaluation of the modiolar research array--multi-centre collaborative study in human temporal bones

OBJECTIVE

Multi-centre collaborative study to develop and refine the design of a prototype thin perimodiolar cochlear implant electrode array and to assess feasibility for use in human subjects.

STUDY DESIGN

Multi-centre temporal bone insertion studies.

MATERIALS AND METHODS

The modiolar research array (MRA) is a thin pre-curved electrode that is held straight for initial insertion with an external sheath rather than an internal stylet. Between November 2006 and February 2009, six iterations of electrode design were studied in 21 separate insertion studies in which 140 electrode insertions were performed in 85 human temporal bones by 12 surgeons. These studies aimed at addressing four fundamental questions related to the electrode concept, being: (1) Could a sheath result in additional intra-cochlear trauma? (2) Could a sheath accommodate variations in cochlea size and anatomies? (3) Could a sheath be inserted via the round window? and (4) Could a sheath be safely removed once the electrode had been inserted? These questions were investigated within these studies using a number of evaluation techniques, including X-ray and microfluoroscopy, acrylic fixation and temporal bone histologic sectioning, temporal bone microdissection of cochlear structures with electrode visualization, rotational tomography, and insertion force analysis.

RESULTS

Frequent examples of electrode rotation and tip fold-over were demonstrated with the initial designs. This was typically caused by excessive curvature of the electrode tip, and also difficulty in handling of the electrode and sheath. The degree of tip curvature was progressively relaxed in subsequent versions with a corresponding reduction in the frequency of tip fold-over. Modifications to the sheath facilitated electrode insertion and sheath removal. Insertion studies with the final MRA design demonstrated minimal trauma, excellent perimodiolar placement, and very small electrode dimensions within scala tympani. Force measurements in temporal bones demonstrated negligible force on cochlear structures with angular insertion depths of between 390 and 450°.

CONCLUSION

The MRA is a novel, very thin perimodiolar prototype electrode array that has been developed using a systematic collaborative approach. The different evaluation techniques employed by the investigators contributed to the early identification of issues and generation of solutions. Regarding the four fundamental questions related to the electrode concept, the studies demonstrated that (1) the sheath did not result in additional intra-cochlear trauma; (2) the sheath could accommodate variations in cochlea size and anatomies; (3) the sheath was more successfully inserted via a cochleostomy than via the round window; and (4) the sheath could be safely removed once the electrode had been inserted.

Managing Cochlear Implant Complications

Program Description: This miniseminar is designed for otolaryngologists who include cochlear implants in the scope of their practice and would like to learn more about managing various intraoperative and postoperative complications, and special considerations as they inevitably arise. Particularly useful for otologic surgeons who have small to moderate cochlear implant case volumes, this seminar will address common as well as less common complications and provide a framework for systematically and effectively managing them. A panel of experts consists of four otologists who run busy, mature cochlear implant programs and have extensive experience in managing various implant-related issues. During the first hour, each panelist will give a brief presentation. Topics include: analyzing suspected device failures, evaluation and revision of inappropriate electrode placement, management of CSF gushers and leaks, management of skin ulceration, skin breakdown and device exposure, management of wound infection and device infection. The following half hour will be reserved for discussion of individual case scenarios. The moderator will present cases to the expert panel for discussion. Members of the audience are encouraged to participate in the discussion, ask questions, and present their own cases to the panel. Attendees will learn how to avoid common intraoperative complications and how to better manage complications when they do occur. The aim of this miniseminar is to allow the attendees to benefit from the experience of our panelists and provide them with “tried and true” techniques that can be implemented in their own cochlear implant programs, ultimately improving the scope and quality of cochlear implant services available nationally and internationally.

Educational Objectives: 1) Identify and manage a variety of complications related to cochlear implants with more confidence. 2) Learn to evaluate suspected cochlear implant device failures and need for revisions. 3) Learn an operative technique for managing a CSF gusher.

Emerging Technologies in Implantable Auditory Prostheses

Program Description: Current prosthetic auditory implants have achieved a high level of success, however, it would be fair to say that performance gains over the past decade have reached a stable plateau. The latest phase of development has centered primarily on increasing stimulus resolution, preserving residual auditory ultrastructure and function, and implanting higher order neural pathways. To serve these objectives, electrodes have been designed to more closely approximate the spiral ganglion and be inserted virtually atraumatically. Implantation of the higher order pathways has already been performed with combinations of penetrating needles or electrode paddles at the brainstem. Prototypes even exist for stimulation as high up as the auditory cortex. We are now also witnessing the development of highly focused fiberoptic delivery systems for infrared laser energy as the stimulus source. A panel of surgeons and scientists, all of whom have been involved in both clinical and basic science of auditory implants, will debate the strategies being developed to foster the next leap in performance gains. The seminar will begin with a candid appraisal of the successes of currently marketed achievements including modiolar hugging electrodes, hearing preservation hybrid implants, compressed and split arrays for severely malformed and obstructed cochleae, and bilateral implantation. Minimally invasive surgical techniques will be examined with the questions posed: What truly constitutes a minimally invasive procedure? What technical features need to be retained in order to maintain necessary safeguards and precautions? The variable successes of auditory brainstem implantation will be reviewed with an eye toward future improvement. The panelists will then present their collective experience with emerging technologies aiming to push the envelope of performance higher into the future. The constant gains in microprocessor speeds will offer opportunities for development of novel processing strategies including current steering. The emerging concept of integrated drug delivery systems will require a careful re-exploration of the well-known design problems of hermeticity, durability, and ultrastructural trauma induction. Changes in stimulus energy source (eg, infrared laser) will undoubtedly require radical changes in device designs and coding strategies. It is the hope of the organizers that this miniseminar will benefit both the attendees and the panelists through the process of evaluative debate and exploration of new ideas.

Educational Objectives: 1) Understand the current status and future direction of hybrid “hearing preservation” cochlear implantation. 2) Understand the newest device and coding strategies including infrared laser optical based devices. 3) Be familiar with the current systems under development including vestibular prostheses, DACS and ABI.

Auditory rehabilitation of patients with neurofibromatosis Type 2 by using cochlear implants

OBJECT

The aim of this study was to determine whether patients with neurofibromatosis Type 2 (NF2) who have intact ipsilateral cochlear nerves can have open-set speech discrimination following cochlear implantation.

METHODS

Records of 7 patients with documented NF2 were reviewed to determine speech discrimination outcomes following cochlear implantation. Outcomes were measured using consonant-nucleus-consonant words and phonemes; Hearing in Noise Test sentences in quiet; and City University of New York sentences in quiet and in noise.

RESULTS

Preoperatively, none of the patients had open-set speech discrimination. Five of the 7 patients had previously undergone excision of ipsilateral vestibular schwannoma (VS). One of the patients who received a cochlear implant had received radiation therapy for ipsilateral VS, and another was undergoing observation for a small ipsilateral VS. Following cochlear implantation, 4 of 7 patients with NF2 had open-set speech discrimination following cochlear implantation during extended follow-up (15-120 months). Two of the 3 patients without open-set speech understanding had a prolonged period between ipsilateral VS resection and cochlear implantation (120 and 132 months), and had cochlear ossification at the time of implantation. The other patient without open-set speech understanding had good contralateral hearing at the time of cochlear implantation. Despite these findings, 6 of the 7 patients were daily users of their cochlear implants, and the seventh is an occasional user, indicating that all of the patients subjectively gained some benefit from their implants.

CONCLUSIONS

Cochlear implantation can provide long-term auditory rehabilitation, with open-set speech discrimination for patients with NF2 who have intact ipsilateral cochlear nerves. Factors that can affect implant performance include the following: 1) a prolonged time between VS resection and implantation; and 2) cochlear ossification.

Direct Facial-to-Hypoglossal Neurorrhaphy with Parotid Release

OBJECTIVE

Facial nerve paralysis or compromise can be caused by lesions of the temporal bone and cerebellopontine angle and their treatment. When the facial nerve is transected or severely compromised and primary end-to-end repair is not possible, hypoglossal-facial nerve anastomosis remains the most popular method for accomplishing three main goals: restoring facial tone, restoring facial symmetry, and facilitating return of voluntary facial movement. Our objectives are to evaluate the surgical feasibility and long-term outcomes of our technique of direct facial-to-hypoglossal neurorrhaphy with a parotid-release maneuver.

DESIGN

Prospective cohort.

SETTING

Academic tertiary care referral center.

PATIENTS

Ten patients with facial paralysis from proximal nerve injury underwent the facial-hypoglossal neurorrhaphy with a parotid-release maneuver.

MAIN OUTCOME MEASURES

The Repaired Facial Nerve Recovery Scale, questionnaires, and photographs.

RESULTS

Facial-hypoglossal neurorrhaphy with parotid release was technically feasible in all cases, and anastomosis was performed distal to the origin of the ansa hypoglossi. All patients had good return of facial nerve function. Nine patients had scores of C or better, indicating strong eyelid and oral sphincter closure and mass motion. There was no hemilingual atrophy and no subjective tongue dysfunction.

CONCLUSIONS

The parotid-release maneuver mobilizes additional length to the facial nerve, facilitating a tensionless communication distal to the ansa hypoglossi. The technique is a viable option for facial reanimation, and our patients achieved good clinical outcomes with continual improvement.

Sphenoid cranial base defects in siblings presenting with cerebrospinal fluid leak

Two sisters presented to our medical center with nontraumatic cerebrospinal fluid (CSF) fistulas from left sphenoid sinocranial junction defects. One sister had recurrent meningitis over a 20-year period that prompted a skull base evaluation. Four years later, her younger sister presented with profuse CSF rhinorrhea. Transethmoid sphenoidotomy with sinus obliteration and lumbar-subarachnoid temporary CSF diversion successfully treated one sister, while the other required reoperation and permanent lumbar-peritoneal shunting. In both cases the skull base defect was identically located in the posterolateral left sphenoid sinus. Embryological considerations, evaluation and management are presented.

Processed allograft: novel use in facial nerve repair after resection of a rare racial nerve paraganglioma

OBJECTIVES

To present a rare case of facial nerve paraganglioma and novel use of a processed allograft for facial nerve reconstruction.

STUDY DESIGN

Case report and review of the literature.

METHODS

A 34 year old female presented with progressive onset right sided facial palsy for 5 months. CT and MRI demonstrated an irregular mass in the right facial nerve canal from the intratympanic segment to the stylomastoid foramen.

RESULTS

Following transmastoid resection, the defect was repaired using processed allograft. Pathologic analysis was consistent with a paraganglioma. Facial nerve paraganglioma is a rare entity that has been reported only 10 times in the literature.

CONCLUSIONS

Traditional methods of facial nerve reconstruction, including autologous and cadaveric grafting, can lead to significant patient morbidity. Autologous nerve grafts are the "gold standard" for superior regenerative capability, but are limited by the length and potential neuroma formation at the donor site. Allogenic grafts from donors or cadavers have shown some efficacy, but can require immunosuppression. The Avance nerve graft is a cadaveric graft, processed and decellularized to maintain an extracellular matrix with laminin and intact endoneural tubes, thus providing support for the growing axon without generating an immune response. Initial studies of the Avance graft in animals and humans have examined repair of peripheral nerves, but this is the first reported case of human facial nerve reconstruction.