Artur Lorens

Preservation of low frequency hearing in partial deafness cochlear implantation (PDCI) using the round window surgical approach

Conclusion. Successful hearing preservation is possible in individuals with excellent low frequency hearing. This is possible due to the partial insertion of an atraumatic electrode using an atraumatic round window surgical technique. Objectives. This paper describes the round window surgical technique used to preserve excellent low frequency hearing in patients receiving partially inserted MED-EL cochlear implant electrodes. Results of preserved low frequency hearing in partial deafness cochlear implantation (PDCI) are reported. Patients and methods. The surgical approach is described in detail. Ten subjects received a partial insertion of a standard electrode, using the round window approach. Pure tone audiometry was conducted in the implanted and non-implanted ear preoperatively, at implant fitting and then at 1, 3, 6 and 12 months after initial device fitting. Results. Results show hearing preservation in 9 of the 10 subjects. One subject lost all hearing 2 weeks after cochlear implantation. Hearing has remained essentially stable up to the 1 year postoperative period. Eight of the nine subjects use the cochlear implant together with their natural low frequency hearing; one subject uses a hearing aid in the implanted ear to amplify the low frequencies.

Preservation of Residual Hearing in Children and Post-Lingually Deafened Adults after Cochlear Implantation: An Initial Study

Objective: To investigate whether the residual hearing of severely hearing-impaired children and adults could be preserved using the soft surgery approach. Patients and Methods: This project employed a prospective study design. All testing and surgery took place in the Institute of Physiology and Pathology of Hearing, Warsaw, Poland. Twenty-six patients (7 children and 19 post-lingually deafened adults) with residual hearing were assessed. Subjects were assessed using conventional pure-tone audiometry at least 1 month prior to surgery. Cochlear implant surgery with a Med-El Combi 40/40+ standard electrode array was conducted, using the soft surgery approach. Pure-tone audiometry thresholds were re-assessed at least 1 month after surgery. The researchers assessed change in auditory thresholds using pure-tone audiometry to determine preservation of residual hearing. Results: Sixteen of 26 patients (62%) retained their residual hearing within 5 dB HL of pre-operative scores. Only 5 of 26 patients (19%) lost all measurable residual hearing after cochlear implantation. This suggests that surgeons are often able to preserve residual hearing during cochlear implant surgery using the soft surgery technique. Conclusions: Preservation of residual hearing is an important consideration in cochlear implantation in the light of changing selection criteria for cochlear implant candidates, and as younger children are receiving implants. This is important, as we do not know yet the long-term effects of inner ear damage due to traumatic insertions of electrodes. This finding suggests a good prognosis for future possibilities of re-implantation.

Partial deafness cochlear implantation provides benefit to a new population of individuals with hearing loss

Conclusion. Partial deafness cochlear implantation (PDCI) is a feasible means of treating individuals who have good low frequency hearing, but a severe to profound hearing loss in the mid to high frequencies. The individuals have benefit in noise and show significant benefit in a number of difficult listening conditions, when compared with their acoustic-only hearing prior to implantation. This benefit is maintained over time. Objectives. PDCI using the round window surgical technique is one means of treating individuals with a ‘ski-slope’ hearing loss, who gain minimal benefit from amplification with conventional hearing instruments. This paper aims to demonstrate the benefit that PDCI provides these individuals. Patients and methods. Ten subjects received a partial insertion of a standard MED-EL electrode, using the round window approach. Pure tone audiometry and monosyllable testing in quiet and noise were conducted preoperatively, at implant fitting and then at 1, 3, 6 and 12 months after initial device fitting. The APHAB questionnaire was completed by subjects preoperatively and then at 6 and 12 months after receiving their cochlear implant. Results. Hearing was preserved in 9 of 10 cases. One subject uses a hearing aid to amplify low frequency hearing, the remainder use natural low frequency hearing. Improvements in monosyllabic scores over time in both quiet and noise were significant, particularly within the first 3 months of PDCI use.

Cochlear implantation with hearing preservation yields significant benefit for speech recognition in complex listening environments

Objective: The aim of this study was to assess the benefit of having preserved acoustic hearing in the implanted ear for speech recognition in complex listening environments. Design: The present study included a within-subjects, repeated-measures design including 21 English-speaking and 17 Polish-speaking cochlear implant (CI) recipients with preserved acoustic hearing in the implanted ear. The patients were implanted with electrodes that varied in insertion depth from 10 to 31 mm. Mean preoperative low-frequency thresholds (average of 125, 250, and 500 Hz) in the implanted ear were 39.3 and 23.4 dB HL for the English- and Polish-speaking participants, respectively. In one condition, speech perception was assessed in an eight-loudspeaker environment in which the speech signals were presented from one loudspeaker and restaurant noise was presented from all loudspeakers. In another condition, the signals were presented in a simulation of a reverberant environment with a reverberation time of 0.6 sec. The response measures included speech reception thresholds (SRTs) and percent correct sentence understanding for two test conditions: CI plus low-frequency hearing in the contralateral ear (bimodal condition) and CI plus low-frequency hearing in both ears (best-aided condition). A subset of six English-speaking listeners were also assessed on measures of interaural time difference thresholds for a 250-Hz signal. Results: Small, but significant, improvements in performance (1.7–2.1 dB and 6–10 percentage points) were found for the best-aided condition versus the bimodal condition. Postoperative thresholds in the implanted ear were correlated with the degree of electric and acoustic stimulation (EAS) benefit for speech recognition in diffuse noise. There was no reliable relationship among measures of audiometric threshold in the implanted ear nor elevation in threshold after surgery and improvement in speech understanding in reverberation. There was a significant correlation between interaural time difference threshold at 250 Hz and EAS-related benefit for the adaptive speech reception threshold. Conclusions: The findings of this study suggest that (1) preserved low-frequency hearing improves speech understanding for CI recipients, (2) testing in complex listening environments, in which binaural timing cues differ for signal and noise, may best demonstrate the value of having two ears with low-frequency acoustic hearing, and (3) preservation of binaural timing cues, although poorer than observed for individuals with normal hearing, is possible after unilateral cochlear implantation with hearing preservation and is associated with EAS benefit. The results of this study demonstrate significant communicative benefit for hearing preservation in the implanted ear and provide support for the expansion of CI criteria to include individuals with low-frequency thresholds in even the normal to near-normal range.

Outcomes of treatment of partial deafness with cochlear implantation: a DUET study.

Objectives: To compare speech test performance of adults with partial deafness cochlear implantation (PDCI) with that of adults with cochlear implant (CI). Based on the results, our objective is to determine the efficacy of the two applications of cochlear implantation, the first characterized by a shallow electrode insertion and preservation of low‐frequency natural hearing for partial deafness, and the second characterized by a very deep electrode insertion used in subjects with severe to profound deafness. All the PDCI participants in this study were fitted with a recently upgraded DUET Hearing System from Med‐El Corporation, Innsbruck, Austria.

Partial Deafness Treatment with the Nucleus Straight Research Array Cochlear Implant

Introduction: The Nucleus Straight Research Array (SRA) cochlear implant has a new 25-mm electrode carrier designed to minimize insertion trauma, in particular allowing easy insertion via the round window. The aims of this study were to measure preoperative to postoperative benefit in terms of speech recognition in quiet and in noise in three groups of patients (electrical complement, EC; electrical stimulation, ES; electro-acoustic stimulation, EAS) with varying levels of low-frequency hearing, and to evaluate the preservation of residual hearing after implantation with the SRA cochlear implant. Methods: The study design was prospective with sequential enrolment and within-subject comparisons: 23 adult cochlear implant candidates were divided into three groups according to their level of preoperative residual hearing at 500 Hz (EC ≤50 dB; 50 dB < EAS < 80 dB; ES ≧80 dB). Monosyllabic word recognition using the SRA cochlear implant in combination with residual low-frequency hearing was assessed at 4 and 13 months after implantation. Hearing threshold levels were also monitored over time. Results: Subjects across all three groups had significant improvements in speech recognition scores (i.e. >20 percentage points) both for listening in quiet (71% of subjects) and in noise (100% of subjects). The average score at 4 months after operation for words presented in quiet was 61.7%, and in 10 dB SNR noise 46.5%, compared to 34.4 and 10.6% preoperatively (p < 0.001). All subjects retained measurable hearing at 500 Hz in the implanted ear at 4 months after the operation; mean increases were 19, 29 and 1 dB for the EC, EAS and ES groups (n = 21). Across frequencies of 125–1000 Hz, the median increase in thresholds was 15 dB up to 13 months postoperatively (n = 15). Conclusions: Speech recognition performance of subjects with various levels of residual low-frequency hearing was significantly improved with the SRA cochlear implant. A high level and rate of hearing preservation was achieved with the SRA implanted using a round window surgical technique. Subjects with preoperative low-frequency hearing levels between 50 and 80 dB HL (EAS group) tended to lose more hearing than those with either better or worse hearing.

Results of Partial Deafness Cochlear Implantation Using Various Electrode Designs

Nineteen adults and 9 children who received a unilateral cochlear implant between 2002 and 2007 were included in the study. All subjects were preoperatively diagnosed with significant residual hearing in low frequencies, termed as ‘partial deafness’, and were implanted according to a 6-step round window surgical technique for partial deafness cochlear implantation. Hearing was preserved to a great extent in the partial deafness cochlear implantation (PDCI) group. After a short period following activation of the cochlear implant, highly significant improvement in the recognition of monosyllabic words was observed. With a developed round window surgical procedure and limited electrode insertion, hearing can be preserved in the majority of patients with partial deafness. PDCI is a feasible means of treating individuals who have good low-frequency hearing but severe to profound hearing loss in the mid to high frequencies.

Atraumatic round window deep insertion of cochlear electrodes

Abstract Conclusion: This study shows that by using the round window approach and deep insertion, it is possible to reduce electrode insertion trauma (EIT), as indicated by the results of the hearing preservation marker. Objectives: In this prospective study EIT was evaluated in 42 subjects with low frequency hearing before surgery with 28 mm round window deep insertion. Methods: The degree of hearing preservation was a marker of EIT. Pure tone audiometry, monosyllable testing was conducted preoperatively and then at 3, 6, and 13 months after surgery. Results: Immediate hearing preservation (3 months postoperatively) was 92.9% (39/42). The surgery-related hearing preservation 13 months after surgery varied from 85% (34/40) to 90% (36/40). The ipsilateral implanted ear showed significant differences between preoperative and postoperative hearing thresholds (p < 0.005). Comparisons of thresholds for the control ear showed a significant difference between preoperative and postoperative thresholds tested 13 months after surgery (p < 0.05). When the subtraction factor of the mean contralateral hearing loss for each tested frequency for the same time interval was applied to the implanted ear, no significant hearing loss was found, showing that postoperative ipsilateral progressive hearing loss was caused by etiology rather than surgery.

Cochlear Implantation With the Nucleus Slim Straight Electrode in Subjects With Residual Low-Frequency Hearing.

Objectives: To measure benefit in terms of speech recognition in quiet and in noise, and conservation of residual hearing in three groups of subjects implanted with the Nucleus Straight Research Array cochlear implant. This device incorporates the Nucleus Slim Straight electrode carrier designed to be easier to insert into the cochlea via the round window while potentially minimizing insertion trauma. Design: The study was prospective, with sequential enrolment and within-subject repeated measures; 35 subjects were 15 to 84 years of age with varying levels of bilateral high-frequency HL. Subjects were divided into three groups (A, B, and C) according to preoperative air conduction hearing thresholds in the ear to implant at 500 Hz; A ⩽ 50 (n = 11), 50 < B < 80 (n = 13), and C ≥ 80 (n = 11) dB HL. Speech recognition was assessed preoperatively and at intervals up to 1 year postimplantation. Hearing thresholds were monitored over time and CT scans were used to estimate electrode positions. Results: Preoperative mean word recognition score was significantly greater for group A compared with group C in quiet (diff. 26.6%pts, p < 0.05), but not so in noise (diff. 7.9%pts, p = 0.72). However, a greater proportion of subjects in group A (81%) achieved a “worthwhile” gain in speech recognition score (>20%pts) in quiet compared with group C (63%). More importantly, for speech recognition in noise, all subjects in groups A and B achieved a >20%pts gain compared with only 73% in group C. Hearing in implanted ears was well conserved for low frequencies, both initially and up to 12 months postoperatively (15 dB median increase in thresholds 250 to 500 Hz). Only 3 of 35 (9%) cases lost all residual hearing in the implanted ear by 12 months. Where characteristic frequency corresponded to a position occupied by the electrode array, threshold increase was correlated with the preoperative hearing threshold (r = 0.7; p < 0.001) and closely approximated reported estimates of residual outer hair cell gain. For characteristic frequencies at positions apical to the electrode tip, the relation between threshold increase and residual hearing decreased in amplitude at 45 to 135 degrees (r = 0.42; p < 0.05), and disappeared at >135 degrees (r = 0.05; p > 0.05). Conclusion: Gains in speech recognition scores for subjects with better residual low-frequency hearing were greater or equal to those obtained by subjects with poorer residual hearing. Residual hearing after cochlear implantation with the Nucleus Slim Straight electrode array was well conserved across all three groups. It appears that the gain provided by outer hair cell function may be completely suppressed when an electrode array is in close proximity to the organ of Corti.

Hearing preservation surgery: Psychophysical estimates of cochlear damage in recipients of a short electrode array

In the newest implementation of cochlear implant surgery, electrode arrays of 10 or 20 mm are inserted into the cochlea with the aim of preserving hearing in the region apical to the tip of the electrode array. In the current study two measures were used to assess hearing preservation: changes in audiometric threshold and changes in psychophysical estimates of nonlinear cochlear processing. Nonlinear cochlear processing was evaluated at signal frequencies of 250 and 500 Hz using Schroeder phase maskers with various indices of masker phase curvature. A total of 15 normal-hearing listeners and 13 cochlear implant patients (7 with a 10 mm insertion and 6 with a 20 mm insertion) were tested. Following surgery the mean low-frequency threshold elevation was 12.7 dB (125-750 Hz). Nine patients had postimplant thresholds within 5-10 dB of preimplant thresholds. Only one patient, however, demonstrated a completely normal nonlinear cochlear function following surgery--although most retained some degree of residual nonlinear processing. This result indicates (i) that Schroeder phase masking functions are a more sensitive index of surgical trauma than audiometric threshold and (ii) that preservation of a normal cochlear function in the apex of the cochlea is relatively uncommon but possible.