Auditory Brainstem Implantation in a 16-Month-Old Boy With Cochlear Hypoplasia

Rounded Insertion Technique for Cochlear Implantation Surgery to Treat Cystic Inner Ear Malformation

OBJECTIVE

This article outlines the advantages and applicability of the rounded insertion technique of cochlear implants in patients with cystic inner ear malformation. This technique enables the insertion of the maximum number of electrodes and prevents the unwanted entry of electrodes into the internal auditory canal.

METHODS

We conducted a retrospective chart review of consecutive patients with cochlear hypoplasia (CH) and/or common cavity (CC) who underwent CI (cochlear implantation) via rounded insertion technique. The position of the electrode array in each patient was confirmed postoperatively via X-ray, and the number of functional electrodes was confirmed during the mapping process.

RESULTS

This study included five male and two female patients (median age: 3 years; age range: 2-7 years). Among the seven patients, four received a cochlear implant on the right side, one on the left side, and two bilaterally. Of the nine ears, six were cases of CH, and three were CC. All cochlear implant surgeries via rounded insertion technique were completed without complications. The maximum number of electrode contacts with fair function in the cystic cochlea was confirmed via postoperative X-ray and the subsequent mapping process.

CONCLUSION

This consecutive series of patients demonstrated the safety and reliability of rounded insertion technique for CI in patients with CH and/or CC.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:2229-2233, 2020.

Effect of anesthesia on evoked auditory responses in pediatric auditory brainstem implant surgery

OBJECTIVE

Electrically evoked auditory brainstem responses (EABR) guide placement of the multichannel auditory brainstem implant (ABI) array during surgery. EABRs are also recorded under anesthesia in nontumor pediatric ABI recipients prior to device activation to confirm placement and guide device programming. We examine the influence of anesthesia on evoked response morphology in pediatric ABI users by comparing intraoperative with postoperative EABR recordings.

STUDY DESIGN

Retrospective review.

METHODS

Seven children underwent ABI surgery by way of retrosigmoid craniotomy. General anesthesia included inhaled sevoflurane induction and propofol maintenance during which EABRs were recorded to confirm accurate positioning of the ABI. A mean of 7.7 ± 2.8 weeks following surgery, the ABI was activated under general anesthesia or sedation (dexmedetomidine) and EABR recordings were made. A qualitative analysis of intraoperative and postoperative waveform morphology was performed.

RESULTS

Seven subjects (mean age 20.6 months) underwent nine ABI surgeries (seven primary, two revisions) and nine activations. EABRs were observed in eight of nine postoperative recordings. In three cases, intraoperative EABRs during general anesthesia were similar to postoperative EABRs with sedation. In one case, sevoflurane and propofol were used for intra- and postoperative recordings, and waveforms were also similar. In four cases, amplitude and latency changes were observed for intraoperative versus postoperative EABRs.

CONCLUSION

Similarity of EABR morphology in the anesthetized versus sedated condition suggests that anesthesia does not have a large effect on far-field evoked potentials. Changes in EABR waveform morphology observed postoperatively may be influenced by other factors such as movements of the surface array.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:507-513, 2020.

A mouthful - airway matters in intraoperative neuromonitoring in auditory brainstem implant surgery for the pediatric patient: a case series

BACKGROUND

The Auditory brainstem implant (ABI) is a new surgical option for hearing impaired children. Intraoperative neurophysiology monitoring includes brainstem mapping of cranial nerve (CN) IX, X, XI, XII and their motor nuclei, and corticobulbar tract motor-evoked potential. These require laryngeal electrodes and intra-oral pins, posing a challenge to airway management especially in the pediatric airway, where specialized electromyogram (EMG) tracheal tubes are not available. Challenges include determining the optimum position on the endotracheal tube (ETT) in which to place laryngeal electrode, and the increase in external diameter of ETT contributed by the wrapping the electrode around the shaft of ETT; this may necessitate downsizing of the tracheal tube. An appropriate size ETT minimizes displacement, which in turn can affect electrode contact with the vocal cords. Finally, a small thus crowded pediatric airway makes for difficult visualization during placement of intraoral neuromonitoring electrodes. The use of a videolaryngoscope helps determine optimum electrode placement.

CASE PRESENTATION

We describe intraoperative neurophysiology monitoring and airway management for the first two ABI procedures in Singapore, conducted for children with congenitally absent cochlear nerves.

CONCLUSION

Neurophysiology cranial nerve IX, X, XII monitoring in the ABI procedure requires intraoral placement of electrodes. Care should be exercised during placement and removal. Vagus nerve monitoring in children requires attention to tube preparation, and consideration should be given to avoidance of airway topicalization.

Assessing the Benefit-Risk Profile for Pediatric Implantable Auditory Prostheses

BACKGROUND/AIMS

Children with congenital cochleovestibular abnormalities associated with profound hearing loss have few treatment options if cochlear implantation does not yield benefit. An alternative is the auditory brainstem implant (ABI). Regulatory authority device approvals currently include a structured benefit-risk assessment. Such an assessment, for regulatory purposes or to guide clinical decision making, has not been published, to our knowledge, for the ABI and may lead to the design of a research program that incorporates regulatory authority, family, and professional input.

METHODS

Much structured benefit-risk research has been conducted in the context of drug trials; here we apply this approach to device studies. A qualitative framework organized benefit (speech recognition, parent self-report measures) and risk (surgery- and device-related) information to guide the selection of candidates thought to have potential benefit from ABI.

RESULTS

Children with cochleovestibular anatomical abnormalities are challenging for appropriate assessment of candidacy for a cochlear implant or an ABI. While the research is still preliminary, children with an ABI appear to slowly obtain benefit over time. A team of professionals, including audiological, occupational, and educational therapy, affords maximum opportunity for benefit.

CONCLUSIONS

Pediatric patients who have abnormal anatomy and are candidates for an implantable auditory prosthetic require an individualized, multisystems review. The qualitative benefit-risk assessment used here to characterize the condition, the medical need, potential benefits, risks, and risk management strategies has revealed the complex factors involved. After implantation, continued team support for the family during extensive postimplant therapy is needed to develop maximum auditory skill benefit.

Audiologic and radiologic findings in cochlear hypoplasia

OBJECTIVE

The aim of the current study is to evaluate audiologic and radiologic findings of cochlear hypoplasia which is a subgroup of inner ear malformations.

METHODS

This study was a prospective clinical study and based on voluntary participation from cases with cochlear hypoplasia diagnosis. The study was conducted at Hacettepe University, Department of Otolaryngology, Head and Neck Surgery and Department of Audiology. Subjects were selected from an inner ear malformations database. Inclusion criteria were having cochlear hypoplasia for at least one ear. There were 66 subjects with an age range of 12 months and 60 years 5 months. For each subject, pure tone audiometry and tympanometry were applied according to chronological and cognitive age. And also, auditory brainstem response test was applied to when it is need. Subjects' radiologic results were reevaluated to confirm cochlear hypoplasia, cochlear nerve and cochlear aperture.

RESULTS

Cochlear hypoplasia types were statistically significantly different in terms of HL degree. This difference was caused by cochlear hypoplasia type IV group being was statistically different from the other three groups. Like with degree of HL, cochlear hypoplasia groups were statistically different from other three groups in terms of type of hearing loss. Cochlear aperture and cochlear nerve status showed variation according to cochlear hypoplasia type but these differences were not statistically approved.

CONCLUSIONS

In the current study, incidence of cochlear hypoplasia was 23.5% in all inner ear malformation. With this study, it was seen that subtypes of cochlear hypoplasia showed variability in terms of degree and type of hearing loss and also cochlear aperture and cochlear nerve status. Especially cochlear hypoplasia type IV differs from other three cochlear hypoplasia types.

Pediatric Auditory Brainstem Implant Surgery

Auditory brainstem implants (ABIs) provide auditory perception in patients with profound hearing loss who are not candidates for the cochlear implant (CI) because of anatomic constraints or failed CI surgery. Herein, the authors discuss (1) preoperative evaluation of pediatric ABI candidates, (2) surgical approaches, and (3) contemporary ABI devices and their use in the pediatric population. The authors also review the surgical and audiologic outcomes following pediatric ABI surgery. The authors' institutional experience and the nearly 200 cases performed in Europe and the United States indicate that ABI surgery in children can be safe and effective.

Outcomes following Pediatric Auditory Brainstem Implant Surgery: Early Experiences in a North American Center

There are no approved Food and Drug Administration indications for pediatric auditory brainstem implant (ABI) surgery in the United States. Our prospective case series aims to determine the safety and feasibility of ABI surgery in pediatric patients <5 years old with congenital deafness at a tertiary North American center. The inclusion criterion was pre- or postlinguistic deafness in children not eligible for cochlear implantation. Seventeen candidates were evaluated (mean ± SD: age, 2.52 ± 0.39 years). Four patients underwent ABI surgery (age, 19.2 ± 3.43 months), including 4 primary procedures and 1 revision for device failure. Spontaneous device failure occurred in another subject postoperatively. No major/minor complications occurred, including cerebrospinal fluid leak, facial nerve injury, hematoma, and nonauditory stimulation. All subjects detected sound with environmental awareness, and several demonstrated babbling and mimicry. Poor durability of older implants underscores need for updated technology.