Do auditory brainstem implants favor the development of sensory integration and cognitive functions?

BACKGROUND: Information about the development of cognitive skills and the effect of sensory integration in children using auditory brainstem implants (ABIs) is still limited. OBJECTIVE: This study primarily aims to investigate the relationship between sensory processing skills and attention and memory abilities in children with ABI, and secondarily aims to examine the effects of implant duration on sensory processing and cognitive skills in these children. METHODS: The study included 25 children between the ages of 6 and 10 years (mean age: 14 girls and 11 boys) with inner ear and/or auditory nerve anomalies using auditory brainstem implants. Visual-Aural Digit Span Test B, Marking Test, Dunn Sensory Profile Questionnaire were applied to all children. RESULTS: The sensory processing skills of children are statistically significant and positive, and moderately related to their cognitive skills. As the duration of implant use increases, better attention and memory performances have been observed (p < .05). CONCLUSION: The study demonstrated the positive impact of sensory processing on the development of memory and attention skills in children with ABI. It will contribute to evaluating the effectiveness of attention, memory, and sensory integration skills, and aiding in the development of more effective educational strategies for these children.

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.

Auditory performance and language skills in children with auditory brainstem implants and cochlear implants.

PURPOSE: This study aims to evaluate school-age language skills and auditory performance in different listening situations in children with cochlear implants and auditory brainstem implants. METHOD: The study included 60 children between the ages of 5 and 9 years with cochlear implants (CI) and auditory brainstem implants (ABI). The volunteer children were divided into two groups: bimodal CI-ABI and bilateral CI users. Test of Language Development: Primary (TOLD-P:4), which assesses components of language such as phonology, morphology, syntax and semantics, was used to evaluate school-age language skills. Children's Auditory Performance Scale (CHAPS) was used to measure their listening performance in quiet, noisy, multi-stimulus environments and their auditory attention and memory skills in daily life. The correlations between language and auditory performance were analyzed and compared between the two groups. RESULTS: Children with ABI showed poorer performance in school-age language skills and auditory performance in different listening environments (p < 0.05). Significant correlations were between school-age language skills and auditory performance (p < 0.05). CONCLUSION: Improved auditory performance is crucial for the development of school-age language skills. To improve auditory performance in children with ABI in different listening environments, assistive listening devices, acoustic environmental arrangements, informative activities, etc., should be used.

Auditory brainstem implantation: surgical experience and audiometric outcomes in the pediatric population.

OBJECTIVE: Pediatric data regarding treatment via an auditory brainstem implant (ABI) remains sparse. The authors aimed to describe their experience at their institution and to delineate associated demographic data, audiometric outcomes, and surgical parameters. METHODS: An IRB-approved, retrospective chart review was conducted among the authors' pediatric patients who had undergone auditory brainstem implantation between 2012 and 2021. Demographic information including sex, age, race, coexisting syndrome(s), history of cochlear implant placement, average duration of implant use, and follow-up outcomes were collected. Surgical parameters collected included approach, intraoperative findings, number of electrodes activated, and complications. RESULTS: A total of 19 pediatric patients had an ABI placed at the authors' institution, with a mean age at surgery of 4.7 years (range 1.5-17.8 years). A total of 17 patients (89.5%) had bilateral cochlear nerve aplasia/dysplasia, 1 (5.3%) had unilateral cochlear nerve aplasia/dysplasia, and 1 (5.3%) had a hypoplastic cochlea with ossification. A total of 11 patients (57.9%) had a history of cochlear implants that were ineffective and required removal. The mean length of implant use was 5.31 years (0.25-10 years). Two patients (10.5%) experienced CSF-related complications requiring further surgical intervention. The most recent audiometric outcomes demonstrated that 15 patients (78.9%) showed improvement in their hearing ability: 5 with sound/speech awareness, 5 able to discriminate among speech and environmental sounds, and 5 able to understand common phrases/conversation without lip reading. Nine patients (47.4%) are in a school for the deaf and 7 (36.8%) are in a mainstream school with support. CONCLUSIONS: The authors' surgical experience with a multidisciplinary team demonstrates that the retrosigmoid approach for ABI placement in children with inner ear pathologies and severe sensorineural hearing loss is a safe and effective treatment modality. Audiometric outcome data showed that nearly 79% of these patients had an improvement in their environmental and speech awareness. Further multicenter collaborations are necessary to improve these outcomes and potentially standardize/enhance electrode placement.

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.

Auditory Brainstem Implant Outcomes in Tumor and Nontumor Patients: A Systematic Review.

OBJECTIVE: To elucidate the differences in auditory performance between auditory brainstem implant (ABI) patients with tumor or nontumor etiologies. DATA SOURCES: PubMed, Embase, and Web of Science Core Collection from 1990 to 2021. REVIEW METHODS: We included published studies with 5 or more pediatric or adult ABI users. Auditory outcomes and side effects were analyzed with weighted means for closed-set, open-set speech, and categories of auditory performance (CAP) scores. Overall performance was compared using an Adult Pediatric Ranked Order Speech Perception (APROSPER) scale created for this study. RESULTS: Thirty-six studies were included and underwent full-text review. Data were extracted for 662 tumor and 267 nontumor patients. 83% were postlingually deafened and 17% were prelingually deafened. Studies that included tumor ABI patients had a weighted mean speech recognition of 39.2% (range: 19.6%-83.3%) for closed-set words, 23.4% (range: 17.2%-37.5%) for open-set words, 21.5% (range: 2.7%-48.4%) for open-set sentences, and 3.1 (range: 1.0-3.2) for CAP scores. Studies including nontumor ABI patients had a weighted mean speech recognition of 79.8% (range: 31.7%-84.4%) for closed-set words, 53.0% (range: 14.6%-72.5%) for open-set sentences, and 2.30 (range: 2.0-4.7) for CAP scores. Mean APROSPER results indicate better auditory performance among nontumor versus tumor patients (3.5 vs 3.0, P = .04). Differences in most common side effects were also observed between tumor and nontumor ABI patients. CONCLUSION: Auditory performance is similar for tumor and nontumor patients for standardized auditory test scores. However, the APROSPER scale demonstrates better ABI performance for nontumor compared to tumor patients.

Evaluation of language, attention, and memory skills in children with auditory brainstem implants.

PURPOSE: This study aimed to evaluate attention, memory, and language skills in children with auditory brainstem implants and cochlear implants. METHODS: This study included 20 children with auditory brainstem implants (ABI) and 20 cochlear implanted (CI) children between the ages of 6 years and 8 years 11 months and their families. "Test of Language Development: Primary (TOLD-P:4)" was used to assess language skills, "STROOP Test, Visual-Aural Digit Span (VADS) test, and Cancellation Test" were used to evaluate attention and memory skills. In addition, the functional outcomes of hearing skills in daily life were scored by "Auditory Behavior in Everyday Life (ABEL) scale". The significance level was determined as 0.05. RESULTS: Children with ABI showed lower language skills than children with CI in terms of TOLD-P:4 language test scores, STROOP sub-test completion times, and the VADS and Cancellation test scores (p < 0.05). In addition, statistically significant correlations were found between language, attention, memory skills, and auditory behavior scale. CONCLUSIONS: This study is one of the limited numbers of studies investigating cognitive processes in children with ABI. Since attention and memory are correlated with language skills, it is recommended that the development of cognition should be considered in follow-up and intervention approaches of children with ABI and/or CI.

Comparing Speech Recognition Outcomes Between Cochlear Implants and Auditory Brainstem Implants in Patients With NF2-Related Schwannomatosis.

OBJECTIVE: To compare cochlear implant (CI) and auditory brainstem implant (ABI) performance in patients with NF2-related schwannomatosis (NF2). STUDY DESIGN: Historical cohort. SETTING: Tertiary academic center. PATIENTS: A total of 58 devices among 48 patients were studied, including 27 ABIs implanted from 1997 to 2022 and 31 CIs implanted from 2003 to 2022. Three patients had bilateral ABIs, three had bilateral CIs, three had an ABI on one side and a CI on the other, one had a CI that was later replaced with an ipsilateral ABI, and one had an ABI and CI concurrently on the same side. INTERVENTIONS: CI or ABI ipsilateral to vestibular schwannoma. MAIN OUTCOME MEASURES: Open-set speech perception, consonant-nucleus-consonant word scores, and AzBio sentence in quiet scores. RESULTS: Among all patients, 27 (47%) achieved open-set speech perception, with 35 (61%) daily users at a median of 24 months (interquartile range [IQR], 12-87 mo) after implantation. Comparing outcomes, CIs significantly outperformed ABIs; 24 (77%) CIs achieved open-set speech perception compared with 3 (12%) ABIs, with median consonant-nucleus-consonant and AzBio scores of 31% (IQR, 0-52%) and 57% (IQR, 5-83%), respectively, for CIs, compared with 0% (IQR, 0-0%) and 0% (IQR, 0-0%), respectively, for ABIs. Patients with ABIs were younger at diagnosis and at implantation, had larger tumors, and were more likely to have postoperative facial paresis. CONCLUSION: Many patients with NF2-associated vestibular schwannoma achieved auditory benefit with either a CI or an ABI; however, outcomes were significantly better in those patients who were able to receive a CI. When disease and anatomy permit, hearing rehabilitation with a CI should be considered over an ABI in these patients. Tumor management strategies that increase the ability to successfully use CIs should be strongly considered given the high risk of losing bilateral functional acoustic hearing in this population.

Hearing Rehabilitation in Patients With Neurofibromatosis Type 2: The Quebec's Experience With Auditory Implants.

OBJECTIVE: To review a single-center experience with hearing rehabilitation in patients with neurofibromatosis type 2 (NF2) and to describe the auditory outcomes of cochlear implants (CIs) and auditory brainstem implants (ABI) in this population. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. PATIENTS: Twelve adult patients with NF2 who received a CI (n = 10) and/or an ABI (n = 5) between 2000 and 2021. INTERVENTIONS: Insertion of a CI and/or an ABI in NF2 patients with bilateral vestibular schwannomas (VSs). MAIN OUTCOME MEASURES: Patients' demographic data, treatment history, hearing evolution, hearing rehabilitation methods, implant details, and auditory outcomes after implantation. RESULTS: Among those who received a CI, five patients had a stable untreated VS, one patient underwent a cochlear nerve preserving surgery, and four patients received radiotherapy treatments. Six patients became regular users of their device. The median open-set sentence recognition scores were as follows: 0.5% preoperatively, 60% at 1 year postoperatively, and 80% on the most recent audiological evaluation. All patients with an ABI were implanted concomitantly with VS surgical excision, and three of them also received radiotherapy treatments. The median open-set sentence recognition scores were as follows: 4% preoperatively, 26% at 1 year postoperatively, and 0% on the most recent evaluation. Three patients became regular ABI users. CONCLUSION: Despite major technological advances, auditory outcomes with ABIs remain deceiving. Considering the overall improvement in postoperative auditory performances provided by CIs compared with ABIs, cochlear implantation standouts as a primary mean of hearing rehabilitation in NF2 patients.

[AUDITORY BRAINSTEM IMPLANTS (ABI) IN CHILDREN: CASE SERIES IN SHAARE ZEDEK MEDICAL CENTER].

BACKGROUND: Cochlear implants (CI) are the treatment of choice for individuals with severe to profound sensorineural hearing loss. A small group of patients, with pathology central to the cochlea, cannot benefit from CI. Examples in children include absence of the cochlear-nerve or cochlear aplasia. In these cases, implantation of an auditory brainstem implant (ABI), directly stimulating the cochlear nucleus, bypassing the inner-ear and auditory-nerve, may be beneficial. OBJECTIVES: Describe a series of children with ABI's treated in Shaare-Zedek, including the first ABI implantation in Israel (2017). METHODS: Of 9 patients with ABI's treated in Shaare Zedek Medical Center ,7 were children implanted between ages 2-8.6 years. Five boys and two girls. Surgeries were conducted in collaboration between neurosurgeons, neurotologists and audiologists (five implanted in Shaare-Zedek and two in New-York University). Follow-up was between 2-6 years. Hearing evaluation was conducted, mainly, with audiograms, categories of auditory performance (CAP), speech perception testing when possible and estimation of device use per day. RESULTS: Six of the seven children, who initially underwent unsuccessful CI, had deficient auditory-nerves. One child had cochlear-aplasia. In 3 children hearing loss was part of the CHARGE syndrome. CAP scores ranged from 0-7 (0,1,3,5,5,7). One child was able to achieve open-set speech perception. CONCLUSIONS: Although functional auditory outcomes for children with ABI are inferior to CI recipients and are highly variable, some children were able to obtain significant benefit. In these children, who are not candidates for CI, the ABI presents the only chance for auditory awareness and may be recommended. DISCUSSION: John Thomas Roland is a consultant and recipient of research support from Cochlear Americas.

Evaluation of auditory brainstem implant (ABI) users' auditory behavior in everyday life.

PURPOSE: This study aims to evaluate the everyday listening status of pediatric ABI users using the Turkish ABEL questionnaire. METHODS: The study included 33 parents of children with auditory brainstem implant, and 28 parents of children with cochlear implant were included as a control group. All implant users were between the ages of 4-14. Parents answered the ABEL questionnaire to assess their child's auditory behavior in their daily living environment. In addition, Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scales were used to evaluate speech perception and production. RESULTS: Auditory-aural, auditory awareness and ABEL total score of ABI users were statistically significantly lower than the CI group (p < 0.05). There was no statistically significant difference between the groups in the Conversational/Social skills subgroups. It was found that as the duration of ABI use increased, auditory-verbal, social skills and total scores increased significantly. In addition, correlations were obtained between ABEL total and subscale scores and CAP and SIR scores. CONCLUSIONS: Parents believe that their children adapt nicely to ABI and are aware of environmental sounds. This study reveals the auditory, aural, and social skills of children using ABI through the regards of their parents. This study showed that the ABEL questionnaire, which was used in previous studies to express parental views of children with hearing aids and cochlear implants, can also be used for parents of children using ABI.

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.

The experience of auditory implant recipients undergoing magnetic resonance imaging: Factors associated with pain.

OBJECTIVE: Many patients with cochlear implants (CI) and auditory brainstem implants (ABI) require magnetic resonance imaging (MRI) following implantation. This study explores the patient experience of MRI, identifying factors associated with pain, and the effect of interventions designed to enhance comfort and safety. METHODS: A prospective observational case series from a tertiary referral unit. Tight head bandaging ± local anaesthetic injection (devices with non-MRI-compatible magnets) or observation alone (implants with MRI-compatible magnets) were employed for 1.5 T MRI of consecutive adult patients with CI or ABI without magnet removal. Pain was recorded via visual analogue scale (1 = no pain, 5 = extreme pain) at three time points; (1) baseline, (2) head bandage applied (3) during scanning. Patient age, device type, body area imaged and total scan time were recorded as variables, alongside adverse events. RESULTS: Data were collected for 227 MRI scans (34 patients with ABI, 32 with CI). In patients managed with bandaging, pain score after bandaging but prior to scanning (median 2.2) did not differ from pain during scanning (2.1), but both were significantly higher than baseline (1.4, both P ≤ 0.001). Scanning areas other than the head/cervical spine was associated with higher pain scores (P = 0.036). Pain during MRI differed between different manufacturers implants (P ≤ 0.001). Adverse events occurred in 8/227 scans (3.5%), none occurring with devices containing an MRI-compatible magnet. CONCLUSION: MRI scanning with auditory implant magnets in situ is safe and well tolerated by patients.

Ten-year follow-up of auditory brainstem implants: From intra-operative electrical auditory brainstem responses to perceptual results.

The auditory brainstem implant (ABI) can provide hearing sensation to individuals where the auditory nerve is damaged. However, patient outcomes with the ABI are typically much poorer than those for cochlear implant recipients. A major limitation to ABI outcomes is the number of implanted electrodes that can produce auditory responses to electric stimulation. One of the greatest challenges in ABI surgery is the intraoperative positioning of the electrode paddle, which must fit snugly within the cochlear nucleus complex. While there presently is no optimal procedure for intraoperative electrode positioning, intraoperative assessments may provide useful information regarding viable electrodes that may be included in patients' clinical speech processors. Currently, there is limited knowledge regarding the relationship between intraoperative data and post-operative outcomes. Furthermore, the relationship between initial ABI stimulation with and long-term perceptual outcomes is unknown. In this retrospective study, we reviewed intraoperative electrophysiological data from 24 ABI patients (16 adults and 8 children) obtained with two stimulation approaches that differed in terms of neural recruitment. The interoperative electrophysiological recordings were used to estimate the number of viable electrodes and were compared to the number of activated electrodes at initial clinical fitting. Regardless of the stimulation approach, the intraoperative estimate of viable electrodes greatly overestimated the number of active electrodes in the clinical map. The number of active electrodes was associated with long-term perceptual outcomes. Among patients with 10-year follow-up, at least 11/21 active electrodes were needed to support good word detection and closed-set recognition and 14/21 electrodes to support good open-set word and sentence recognition. Perceptual outcomes were better for children than for adults, despite a lower number of active electrodes.

Evaluation of the non-auditory responses in individuals with auditory brainstem implant.

OBJECTIVES: After auditory brainstem implant (ABI) surgery, stimulation of certain cranial nerves may result in a non-auditory response, and the electrodes that stimulate these nerves may be deactivated. The goals of this study are to compare the number of active electrodes in the initial activation and the last fitting, to investigate non-auditory response types and their frequency as a result of non-auditory stimulation, to compare the placements of deactivated electrodes as a result of non-auditory stimulation in the initial activation and the last fitting. METHODS: The computer software system was used to perform a retrospective analysis of the fitting data of 69 ABI users who underwent auditory brainstem implant surgery between January 1997 and January 2019. The non-auditory response types, deactive electrodes, and the positioning of the deactive electrodes horizontally and vertically were recorded in these users during the initial activation and the last fitting. RESULTS: There was no statistically significant difference between the number of active electrodes in the initial activation and the last fitting. The proportion of the users with deactive electrodes in the initial activation and the last fitting was not statistically significant different. In the horizontal and vertical placement classification, the placement of the deactive electrodes was not statistically different between initial activation and last fitting. The most common type of non-auditory response was facial nerve stimulation at the initial activation and no auditory perception at the last fitting. According to the difference between the number of active and deactive electrodes in the initial activation and the last fitting, as well as the auditory and non-auditory responses, it was found that the ABI users were statistically different between the initial activation and the last fitting. CONCLUSION: The results of this study show that not only auditory but also non-auditory responses occur in most ABI users. In addition, to the best of our knowledge, this study is the first to examine the frequencies of non-auditory response types, and the placement of the electrodes that cause these responses according to horizontal and vertical classifications.

Hearing and language development in children with brainstem implants: a systematic review.

OBJECTIVE: To present scientific evidence, based on a systematic review of the literature, on the benefit of brainstem implants in auditory rehabilitation and language development in children. METHODS: A systematic search was used to identify studies that contain information about the benefit of brainstem implants in the auditory rehabilitation and language development of children. The review was conducted based on a structured literature search, following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) checklist. The search was carried out in the PubMed, Web of Science and Scopus databases, using the combination "Auditory brainstem implants" AND "Pediatric", without restriction of language, period, and location. The quality assessment of the articles was performed using the Study Quality Assessment Tools. RESULTS: Regarding hearing, children with brainstem implants showed sound detection, access to most speech sounds, basic auditory perception skills, recognition of ambient sounds, recognition of some frequently used words and phrases, in addition to some closed-set word discrimination capability. Expressive and comprehensive language were identified in children using auditory brainstem implants, increasing significantly in the short and long terms in most cases; however, in some of the children, such skills remained stable. CONCLUSION: The auditory brainstem implant can be considered an effective alternative for children with cochlear malformation and/or auditory nerve deficiency and for those who cannot benefit from cochlear implant surgery.

Intraword Variability in Children With Auditory Brainstem Implants: A Longitudinal Comparison With Children With Cochlear Implants.

PURPOSE: Intraword variability designates the phenomenon that a particular target word is produced variably by a child at one point in the child's development. In this study, the amount of intraword variability is studied longitudinally in children with auditory brainstem implants (ABIs). Auditory brainstem implantation is a relative recent technique in pediatric hearing restoration. Therefore, little is known about the phonological development of these children's speech. METHOD: The intraword variability is investigated in three children with ABI, in comparison to children with cochlear implants, matched on lexical development. Intraword variability is measured using relative entropy in order to take into account the frequency distribution in children's productions. RESULT: Results showed considerable variation between the three children with ABI. Still, all children had higher levels of intraword variability in their spontaneous speech productions as compared to children with cochlear implants. CONCLUSION: It seems that children with ABI are lagging behind their phonological development in reference to children with cochlear implants.