ABI-auditory brainstem implant

Auditory brainstem implants: an analysis of adverse events in the MAUDE database

OBJECTIVE

Auditory Brainstem Implants (ABI) are used to restore hearing in patients lacking appropriate cochlear anatomy and/or cochlear nerve. The objective of this study was to examine the Manufacture and User Facility Device Experience (MAUDE) database to analyze adverse events.

STUDY DESIGN

This is a study of a multi-institutional database maintained by the US FDA.

SETTING

A database analysis was performed via collaboration of multiple clinicians at tertiary referral centers.

METHODS

The MAUDE database was queried for Medical Device Reports (MDRs) relating to ABIs. MDRs were identified using the advanced search term "Implant, Auditory Brainstem" and reviewing all reports with the basic search term "Brainstem Implant". All collected reports were individually reviewed.

RESULTS

A total of 265 individual patient reports were reviewed, of which 55 reports met inclusion criteria. Reports regarding audiologic outcome included failure to provide hearing benefit (n = 27), implant failure/device malfunction (n = 10), and device non-use (n = 6). Postoperative complications included local skin infection (n = 3), CSF leak (n = 3), elevated ICP (n = 1), surgical site dehiscence (n = 1), swelling (n = 1), seroma formation requiring drainage (n = 1), and meningitis (n = 2). Two patients had dislodged magnets during 1.5 Tesla MRI acquisition. There were 35 instances of full explantation of the device and 1 partial removal; 13 patients had a new device implanted following explantation.

CONCLUSIONS

Poor hearing results, device failure, and non-use were commonly reported causes for explanation in this analysis. This information can aid physicians in counseling patients and family members and managing device expectations.

Intraoperative assessment of cochlear nerve functionality in various vestibular schwannoma scenarios: Lessons learned

The use of cochlear implants (CIs) is on the rise for patients with vestibular schwannoma (VS). Besides CI following tumor resection, new scenarios such as implantation in observed and/or irradiated tumors are becoming increasingly common. A significant emerging trend is the need of intraoperative evaluation of the functionality of the cochlear nerve in order to decide if a CI would be placed. The purpose of this paper is to explore the experience of a tertiary center with the application of the Auditory Nerve Test System (ANTS) in various scenarios regarding VS patients. The results are compared to that of the studies that have previously used the ANTS in this condition. Patients with unilateral or bilateral VS (NF2) who were evaluated with the ANTS prior to considering CI in a tertiary center between 2021 and 2023 were analyzed. The presence of a robust wave V was chosen to define a positive electrical auditory brainstem response (EABR). Two patients underwent promontory stimulation (PromStim) EABR previous to ANTS evaluation. Seven patients, 2 NF-2 and 5 with sporadic VS were included. The initial scenario was simultaneous translabyrinthine (TL) tumor resection and CI in 3 cases while a CI placement without tumor resection was planned in 4 cases. The ANTS was positive in 4 cases, negative in 2 cases, and uncertain in one case. Two patients underwent simultaneous TL and CI, 1 patient simultaneous TL and auditory brainstem implant, 3 patients posterior tympanotomy with CI, and 1 patient had no implant placement. In the 5 patients undergoing CI, sound detection was present. There was a good correlation between the PromStim and ANTS EABR. The literature research yielded 35 patients with complete information about EABR response. There was one false negative and one false positive case; that is, the 28 implanted cases with a present wave V following tumor resection had some degree of auditory perception in all but one case. The ANTS is a useful intraoperative tool to asses CI candidacy in VS patients undergoing observation, irradiation or surgery. A positive strongly predicts at least sound detection with the CI.

Auditory brainstem implants for hearing rehabilitation in NF2-schwannomatosis: A systematic review and single-arm meta-analysis

BACKGROUND

NF2-schwannomatosis (NF2) is an autosomal dominant disorder prone to hearing loss. Auditory brainstem implants (ABIs) offer a promising solution for hearing rehabilitation in NF2.

OBJECTIVE

To synthesize existing literature on ABI implantation in NF2, focusing on audiological outcomes and ABI-related complications.

METHODS

The systematic review followed PRISMA guidelines and was registered in the PROSPERO database (CRD42022362155). Relevant studies were identified by searching PubMed, EMBASE, CENTRAL, CMB, and CNKI from inception to August 2023. Data on environmental sound discrimination, open-set discrimination, closed-set discrimination, and ABI-related complications were extracted and subjected to meta-analysis. Publication bias was evaluated using funnel plots and Egger's test.

RESULTS

Thirty-three studies were included. The pooled estimate was 58% (95% CI 49-66%) for environmental sound discrimination and 55% (95% CI 40-69%) for closed-set discrimination. Regarding open-set discrimination, the pooled estimates were 30% (95% CI 19-42%) for sound only, 46% (95% CI 37-54%) for lip-reading only, and 63% (95% CI 55-70%) for sound plus lip-reading. The pooled occurrence of ABI-related complications was 33% (95% CI 15-52%).

CONCLUSION

This meta-analysis underscores the effectiveness and safety of ABIs in NF2, providing valuable insights for evidence-based decision-making and hearing rehabilitation strategies.

Management of Central and Peripheral Nervous System Tumors in Patients with Neurofibromatosis

Neurofibromatosis type I (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis represent a diverse group of genetic tumor predisposition syndromes with a shared feature of tumors affecting the peripheral nerve sheaths. PURPOSE OF REVIEW: Many advancements have been made in understanding the biologic underpinnings of these conditions, and in 2016 the first drug was approved by the FDA to treat pediatric symptomatic unresectable plexiform neurofibromas. RECENT FINDINGS: Mek inhibitors have provided a much-needed therapeutic avenue for NF1 patients with unresectable plexiform neurofibromas (PN), both for reduction of tumor bulk and for improvement in symptoms. Selumetinib is the first FDA approved drug for PN, but is only approved for children. Some research suggests that alternative Mek inhibitors and other mixed tyrosine kinase inhibitors may have better efficacy in adults. Vascular endothelial growth factor (VEGF) inhibitor bevacizumab can prolong hearing and delay the need for surgery in NF2 patients with bilateral vestibular schwannomas. This article provides an update regarding considerations and approaches when treating the tumors associated with the neurofibromatoses (NF), including risk and prognosis metrics, clinical trial results, surgical techniques, and radiation therapy recommendations.

Sensitivity to Pulse Rate and Amplitude Modulation in an Animal Model of the Auditory Brainstem Implant (ABI)

The auditory brainstem implant (ABI) is an auditory neuroprosthesis that provides hearing by electrically stimulating the cochlear nucleus (CN) of the brainstem. Our previous study (McInturff et al., 2022) showed that single-pulse stimulation of the dorsal (D)CN subdivision with low levels of current evokes responses that have early latencies, different than the late response patterns observed from stimulation of the ventral (V)CN. How these differing responses encode more complex stimuli, such as pulse trains and amplitude modulated (AM) pulses, has not been explored. Here, we compare responses to pulse train stimulation of the DCN and VCN, and show that VCN responses, measured in the inferior colliculus (IC), have less adaption, higher synchrony, and higher cross-correlation. However, with high-level DCN stimulation, responses become like those to VCN stimulation, supporting our earlier hypothesis that current spreads from electrodes on the DCN to excite neurons located in the VCN. To AM pulses, stimulation of the VCN elicits responses with larger vector strengths and gain values especially in the high-CF portion of the IC. Additional analysis using neural measures of modulation thresholds indicate that these measures are lowest for VCN. Human ABI users with low modulation thresholds, who score best on comprehension tests, may thus have electrode arrays that stimulate the VCN. Overall, the results show that the VCN has superior response characteristics and suggest that it should be the preferred target for ABI electrode arrays in humans.

Use of Invasive Brain-Computer Interfaces in Pediatric Neurosurgery: Technical and Ethical Considerations

Invasive brain-computer interfaces hold promise to alleviate disabilities in individuals with neurologic injury, with fully implantable brain-computer interface systems expected to reach the clinic in the upcoming decade. Children with severe neurologic disabilities, like quadriplegic cerebral palsy or cervical spine trauma, could benefit from this technology. However, they have been excluded from clinical trials of intracortical brain-computer interface to date. In this manuscript, we discuss the ethical considerations related to the use of invasive brain-computer interface in children with severe neurologic disabilities. We first review the technical hardware and software considerations for the application of intracortical brain-computer interface in children. We then discuss ethical issues related to motor brain-computer interface use in pediatric neurosurgery. Finally, based on the input of a multidisciplinary panel of experts in fields related to brain-computer interface (functional and restorative neurosurgery, pediatric neurosurgery, mathematics and artificial intelligence research, neuroengineering, pediatric ethics, and pragmatic ethics), we then formulate initial recommendations regarding the clinical use of invasive brain-computer interfaces in children.

Personalized Medicine in Otolaryngology: Special Topic Otology

Globally, more than 1.5 billion people experience some degree of hearing loss [...].

Comparison of Responses to DCN vs. VCN Stimulation in a Mouse Model of the Auditory Brainstem Implant (ABI)

The auditory brainstem implant (ABI) is an auditory neuroprosthesis that provides hearing to deaf patients by electrically stimulating the cochlear nucleus (CN) of the brainstem. Whether such stimulation activates one or the other of the CN's two major subdivisions is not known. Here, we demonstrate clear response differences from the stimulation of the dorsal (D) vs. ventral (V) subdivisions of the CN in a mouse model of the ABI with a surface-stimulating electrode array. For the DCN, low levels of stimulation evoked multiunit responses in the inferior colliculus (IC) that were unimodally distributed with early latencies (avg. peak latency of 3.3 ms). However, high levels of stimulation evoked a bimodal distribution with the addition of a late latency response peak (avg. peak latency of 7.1 ms). For the VCN, in contrast, electrical stimulation elicited multiunit responses that were usually unimodal and had a latency similar to the DCN's late response. Local field potentials (LFP) from the IC showed components that correlated with early and late multiunit responses. Surgical cuts to sever the output of the DCN, the dorsal acoustic stria (DAS), gave insight into the origin of these early and late responses. Cuts eliminated early responses but had little-to-no effect on late responses. The early responses thus originate from cells that project through the DAS, such as DCN's pyramidal and giant cells. Late responses likely arise from the spread of stimulation from a DCN-placed electrode array to the VCN and could originate in bushy and/or stellate cells. In human ABI users, the spread of stimulation in the CN may result in abnormal response patterns that could hinder performance.

Novel microscope-based visual display and nasopharyngeal registration for auditory brainstem implantation: a feasibility study in an ex vivo model

Purpose

An auditory brainstem implant (ABI) represents an alternative for patients with profound hearing loss who are constrained from receiving a cochlear implant. The positioning of the ABI electrode influences the patient’s auditory capacity and, therefore, quality of life and is challenging even with available intraoperative electrophysiological monitoring. This work aims to provide and assess the feasibility of visual-spatial assistance for ABI positioning.

Methods

The pose of the forceps instrument that grasps the electrode was electromagnetically navigated and interactively projected in the eyepieces of a surgical microscope with respect to a target point. Intraoperative navigation was established with an experimental technique for automated nasopharyngeal patient registration. Two ABI procedures were completed in a human specimen head.

Results

An intraoperative usability study demonstrated lower localization error when using the proposed visual display versus standard cross-sectional views. The postoperative evaluations of the preclinical study showed that the center of the electrode was misplaced to the planned position by 1.58 mm and 3.16 mm for the left and the right ear procedure, respectively.

Conclusion

The results indicate the potential to enhance intraoperative feedback during ABI positioning with the presented system. Further improvements consider estimating the pose of the electrode itself to allow for better orientation during placement.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11548-021-02514-x.