Biomedical subjects

Stephen Bowditch

Publications and source records attributed to Stephen Bowditch.

4 recordsLinked to original sources

PubMed2006

Amplification in the rehabilitation of unilateral deafness: speech in noise and directional hearing effects with bone-anchored hearing and contralateral routing of signal amplification.

OBJECTIVE: Vibromechanical stimulation with a semi-implantable bone conductor (Entific BAHA device) overcomes some of the head-shadow effects in unilateral deafness. What specific rehabilitative benefits are observed when the functional ear exhibits normal hearing versus moderate sensorineural hearing loss (SNHL)? DESIGN: The authors conducted a prospective trial of subjects with unilateral deafness in a tertiary care center. PATIENTS: This study comprised adults with unilateral deafness (pure-tone average [PTA] > 90 dB; Sp.D. < 20%) and either normal monaural hearing (n = 18) or moderate SNHL (PTA = 25-50 dB: Sp.D. > 75%) in the contralateral functional ear (n = 5). INTERVENTIONS: Subjects were fit with contralateral routing of signal (CROS) devices for 1 month and tested before (mastoid) implantation, fitting, and testing with a bone-anchored hearing aid (BAHA). OUTCOME MEASURES: Outcome measures were: 1) subjective benefit; 2) source localization tests (Source Azimuth Identification in Noise Test [SAINT]); 3) speech discrimination in quiet and in noise assessed with Hearing In Noise Test (HINT) protocols. RESULTS: There was consistent satisfaction with BAHA amplification and poor acceptance of CROS amplification. General directional hearing decreased with CROS use and was unchanged by BAHA and directional microphone aids. Relative to baseline and CROS, BAHA produced significantly better speech recognition in noise. Twenty-two of 23 subjects followed up in this study continue to use their BAHA device over an average follow-up period of 30.24 months (range, 51-12 months). CONCLUSION: BAHA amplification on the side of a deaf ear yields greater benefit in subjects with monaural hearing than does CROS amplification. Advantages likely related to averting the interference of speech signals delivered to the better ear, as occurs with conventional CROS amplification, while alleviating the negative head-shadow effects of unilateral deafness. The advantages of head-shadow reduction in enhancing speech recognition with noise in the hearing ear outweigh disadvantages inherent in head-shadow reduction that can occur by introducing noise from the deaf side. The level of hearing impairment correlates with incremental benefit provided by the BAHA. Patients with a moderate SNHL in the functioning ear perceived greater increments in benefit, especially in background noise, and demonstrated greater improvements in speech understanding with BAHA amplification.

Adult↗

PubMed2005

Predictive models for cochlear implantation in elderly candidates.

OBJECTIVE: An aging American population carries a high prevalence of profound sensorineural hearing loss. We examined the performance of multichannel cochlear implant recipients in a large database of adult subjects. DESIGN: Nonconcurrent prospective study of a national cohort with multivariate regression analysis of preoperative and postoperative performance variables in multichannel cochlear implant recipients. We applied models of prediction established in previous studies to the observed results. SETTING: Referral centers with active cochlear implant programs. PATIENTS: Adolescents and adults with profound hearing loss (N = 749; age range, 14-91 years). MAIN OUTCOME MEASURE: Postoperative monosyllabic word recognition. RESULTS: The population 65 years and older demonstrated a clinically insignificant 4.6%-smaller postoperative word score compared with the population younger than 65 years. When duration of deafness exceeded 25 years, elderly recipients demonstrated higher word scores than their younger counterparts. A more significant factor affecting outcomes is the ratio of duration of deafness to age at implantation. CONCLUSIONS: Age at implantation carried relatively little predictive value for postoperative performance in subjects 65 years and older. Although a small decrement in mean speech recognition scores was evident, the clinical significance of this difference is questionable when all of the results observed in elderly patients are considered. A shorter percentage of life spent in severe-to-profound sensorineural hearing loss suggests a foundation of acoustic/auditory processing in the elderly cohort that may mitigate potential physiological effects associated with advanced age. This study confirms and extends previous observations that duration of profound deafness and residual speech recognition carry higher predictive value than the age at which an individual receives an implant.

Adolescent↗

PubMed2005

Cochlear implant outcome is not influenced by the choice of ear.

OBJECTIVES: This study tested the hypothesis that patients with residual hearing in the nonimplanted ear had the same cochlear implant benefit whether the implanted ear had profound or severe hearing loss. DESIGN: A retrospective chart review of adult cochlear implant recipients with postlingual hearing loss. Patients were categorized according to the pure-tone average of the implanted and contralateral ears as (a) bilateral profound, (b) severe-profound, and (c) bilateral severe. The results of a test battery of spoken language measures were compared among patients belonging to these hearing categories at 6, 12, and 24 months after surgery, using a t-test and multivariate regression analyses. RESULTS: The presence of residual hearing in one or both ears was associated with significantly higher postoperative speech perception scores compared with participants with bilateral profound hearing loss. Among participants with similar amounts of residual hearing in the nonimplanted ear, however, there was no difference in speech recognition scores between those with profound and those with severe hearing loss in the implanted ear. CONCLUSIONS: Among participants with asymmetric hearing loss, there is no additional benefit to implanting the better-hearing ear that can be preserved for use with a hearing aid for better speech understanding in noise and sound localization. These results suggest that the additional benefit received by patients with residual hearing is mediated by trophic effects on crossed pathways in the central nervous system and is independent of the preoperative functional status of the implanted ear.

Adult↗

PubMed2005

Serial audiometry in a clinical trial of AIED treatment.

OBJECTIVE: We analyzed pure-tone and speech audiometric results from a prospective trial of anti-inflammatory treatment of subjects with active autoimmune inner ear disease (AIED). We sought to characterize the pattern and size of the treatment effect as reflected in clinical audiometry and to identify audiometric predictors of response to steroid treatment of AIED. SUBJECTS: Adult participants demonstrated clinically established criteria for AIED (n = 116). Eligibility required audiometric evidence of active AIED as indicated by idiopathic sensorineural hearing loss with threshold elevations within 3 months of enrollment. METHODS: We evaluated audiometric changes after 4 weeks of treatment with pharmacologic doses (60 mg/day) of prednisone. We examined the relationship between audiometric pure-tone thresholds at baseline and changes in word intelligibility score (WIS) using parametric and nonparametric analyses. Magnitudes of change were assessed using independent or paired t-tests. Separate analyses were performed on subgroups that did or did not show improved WIS score with steroid treatment. RESULTS: Overall mean pure-tone averages improved from baseline to closeout of prednisone treatment in better hearing ears from 52.4 to 48.3 dB (p < .0001). Mean WIS improved in the better ear from 71.4% to 78.1% (p < .0001). Of pure-tone measures, only the six-tone average showed significant correlation with both the absolute improvements in WIS and with the percentage change in WIS after treatment. Individual frequencies at baseline showed no significant relationship with changes in WIS score after treatment. In 69 (59.5%) of 116 subjects, WIS improved (range, 2-80%) in the better ear. In these subjects, the baseline pure-tone thresholds and pure-tone averages correlated significantly and positively with improvement in WIS. CONCLUSIONS: Steroid treatment in AIED-mediated hearing loss produce variable but significant hearing gains. Neither a focal, cochleotopic region of greatest vulnerability to AIED nor frequency-specific amenability to treatment were evident. We did observe that analysis of predictors and the degree of treatment effect vary with different approaches to measuring change in the WIS. Depending on the approach adopted, the size of the treatment effect may be greatest across intermediate hearing levels at baseline. These observations offer an audiometric database that may enable greater precision in judging clinically meaningful parameters for future studies of AIED treatment and other interventions for sensorineural hearing loss.

Adolescent↗