Abstract
Introduction: Increasing numbers of pre-lingually profoundly deaf adults are seeking a cochlear implant (CI). Pre- and post-operative outcomes are presented on 20 of these patients.
Results: An Adult Pre-Lingually Profoundly Deaf Implant Profile (APDIP) weighted the pre-operative level of concern about potential CI benefit. Results indicated no group mean post-operative open-set improvement. However CUNY sentence testing (auditory plus lip-reading cues) revealed improved performance with a CI. Twelve out of 20 patients used their CIs for more than 10 hours per day, suggesting good usage. Moreover, hours of usage were positively associated with measured benefit on CUNY sentences in the lip-reading plus sound via CI condition. There was no apparent relationship between pre-operative level of concern and post-operative CI performance or hours of processor use.
Conclusion: Results suggest implantation is beneficial and effective in this group.
keywords:
Introduction
Recent years have seen an increase in the number of pre-lingually profoundly deaf adults seeking a cochlear implant (CI). This patient group typically presents with pure tone thresholds poorer than 90 dB HL in the high frequencies and with minimal scores on open-set BKB sentence tests, placing them well within current candidacy recommendations within the NICE Guidelines (CitationNICE, 2009). However the relationship between duration of deafness and outcomes of implantation are well documented. Investigations into criteria for candidacy suggested that cochlear implantation in patients with a duration of profound deafness of more than 30 years was likely to have limited effectiveness. (CitationUK Cochlear Implant Study Group, 2004) As a result this group were unlikely to be considered CI candidates, until recently. However, clinical practice has changed; last year 20% of the implanted patients at The Midlands Hearing Implant Programme (Adult service) (MHIP) were from this group. Indeed, CitationBosco et al. (2010) looked at long-term outcomes of pre-lingually profoundly deaf adults and adolescents and found that while 5/13 had no post-operative open-set speech improvement, the majority used their implants regularly, reported an increase in self esteem and a high level of subjective benefit. Similarly, CitationPeasgood et al. (2003) suggested that ‘non-traditional’ pre or peri-lingually deaf patients who may be considered poor candidates for implantation with regard to performance derive considerable benefits on quality of life measures. Hence, it was anticipated that while these patients would not obtain any improvement in open-set auditory-only speech perception tests with their CI, they would gain benefit. This paper evaluates whether there are other useful ways to determine measurable benefit in this group.
Methods
A retrospective medical notes review was performed on a group of 20 profoundly deaf adult patients, 17 pre-lingually and three peri-lingually deaf, who attended the department for routine clinic appointments and who were assessed and subsequently implanted. Patients were identified as the 20 most recently implanted patients with a history of pre- or peri-lingual profound deafness. All patients received a Cochlear CI422 device; 19 use a CP910 sound processor and one a CP810 processor. The mean age of the group at implantation was 40.66 years (Range: 16.46–69.94 years). See Table for the patient details.
Table 1 Onset and duration of profound deafness, and primary method of communication used by the patient group
A modification of the Adult Implant Profile (AIP) form was devised based on a template from the Royal National Throat Nose and Ear Hospital, London. The revised form, the Adult Pre-Lingually Profoundly Deaf Implant Profile (APDIP) form, focussed more on aspects of duration and onset of profound deafness and mode of communication than the original AIP form and was completed by clinicians during the assessment. It was used to quantify the level of concern about future CI benefit. Aspects of onset and duration of profound deafness, hearing aid use and mode of communication were addressed and allocated a score of 0 points for no concerns, 1 point for moderate concern and 2 points for great concern, for each aspect. A total score of the pre-operative level of concern was then calculated across all domains. The range of possible scores was zero (no concern) to 20 (greatest possible concern). See Appendix 1.
As part of the standard assessment and subsequent review appointments, pre- and post-operative evaluations were performed. These included CUNY sentence testing with lip-reading alone and with lip-reading plus sound through the hearing aid(s) (HAs) or the CI. Open-set auditory-only speech perception was evaluated using BKB sentence tests presented at 70 dBSPL in quiet, pre-operatively with HAs and post-operatively with the CI. Soundfield implant-aided thresholds were evaluated at the Week 1 review appointment using warble tones presented in the soundfield. Incidence of mapping problems such as non-auditory stimulation and any necessary deactivation of electrodes were recorded. Mean hours of daily implant use via datalogging and incidence of non-use were also analysed. Departmental policy at MHIP is to encourage patients to wear their sound processors as much as possible throughout their waking hours and this would be indicated by a minimum of 10 hours mean daily use.
Results
Pre-operative levels of concern were determined from total scores on the APDIP form. Scores ranged from six to 13, indicating that there were concerns about all patients as to whether they would obtain any benefit from a CI.
All patients attended for initial activation approximately 4 weeks post-operatively. Contrary to expectations based on previous anecdotal reports, programming problems were rare. There were two cases of non-auditory stimulation at initial activation but both were resolved by day two. Twelve patients had all 22 electrodes active in the map. Four patients had one electrode deactivated and a further four had up to three electrodes deactivated. No other mapping issues were reported. CI soundfield thresholds were good, with mean responses between 31 and 32 dBA (range = 20–45 dBA) across the frequency range (250–4000 Hz).
Datalogging from 19 patients revealed that 12 patients used their processor for 10 hours a day or more on average. Three patients used their processors for more than 5 hours on average per day. Three patients wore their processors for less than 3 hours per day and there was one confirmed non-user. There was no datalogging data available on the patient with a CP810 processor.
Open-set auditory-only speech perception was evaluated using BKB sentences presented at 70 dBA in quiet. The mean pre-op score with hearing aids was 3.95% (|SD = 6.97) and post-operatively with the CI was 8.9% (SD = 13.3) indicating no significant benefit from the CI with regard to auditory-only speech discrimination. CUNY sentences with lip-reading alone and lip-reading plus sound were presented pre-operatively in the HA condition and post-operatively in the CI condition. It should be noted that this test uses complex language, which may account for the trend towards lower scores in this group of patients, many of whom use BSL as their first language or in addition to speech. The mean score lip-reading alone was 18%. Scores improved with the addition of sound through the hearing aid, with a mean score of 33.73% and was a statistically significant improvement (paired t test: t = −4.46, P = 0.001). Higher scores were also observed post-operatively with sound from the CI. The mean score (lip-reading plus sound from the CI) was 55.6% (interquartile range = 41–72.5%) and was also a significant improvement (paired t test: t = −6.84, P = 0.001). No significant difference between post-operative scores with a HA and with a CI was found (t = −0.561, P = 0.595) although there was a trend towards better performance with the CI (see Fig. ).
Figure 1 A comparison of mean scores in three CUNY conditions: lip-reading alone; lip-reading plus sound via hearing aid(s); lip-reading plus sound via a cochlear implant.
The difference between the pre-operative lip-reading alone score and post-operative lip-reading plus sound with the CI was calculated for each patient to produce a benefit score. The relationship between this level of benefit as measured on the CUNY sentence test and average daily use from datalogging was analysed with the Pearson correlation procedure (see Fig. for a scatterplot). Results suggest patients who wore their processors for longer each day also had higher CUNY benefit scores with their CI and this relationship was significant (R2 = 0.6; P = 0.001).
Figure 2 Scatter plot showing a significant relationship between average daily hours of processor use from datalogging and CI benefit on CUNY sentences (difference between lip-reading alone score and lip-reading plus sound via CI score).
However there was no apparent linear relationship between average daily use and pre-operative levels of concern as measured on the APDIP scale (R2 = 0.061, P = 0.308). Nor was there any apparent relationship between the APDIP score and level of improvement on CUNY sentences with the CI (R2 = 0.173, P = 0.124).
Discussion
Pre-lingually profoundly deaf adults are non-traditional candidates for CI and findings from the CitationUK CI Study Group (2004) suggested they would receive limited benefit from a CI due to the duration of profound deafness. Moreover the MHIP Team had concerns that there would also be potential difficulties in programming in this group. The level of the MHIP Team concern was measured pre-operatively. However results indicated that there was no apparent relationship between the level of concern measured on the APDIP and any other factor including average daily use, level of benefit on CUNY sentences and incidence of programming problems.
A significant relationship was found between the level of CUNY benefit from the CI and hours of daily usage from datalogging. However it is not possible to determine the nature of this relationship and establish whether patients who wear their processors for longer gain greater benefits or whether patients who obtain greater benefits tend to wear the processor for longer. Twelve out of 20 patients wore their sound processors for more than 10 hours on average per day and there was only one confirmed non-user. Hence the proportion of non-use was comparable with that of post-lingually deaf adults (CitationSummerfield & Marshall, 2000).
There was no apparent improvement in open-set speech perception as measured on BKB sentence tests; nine out of 20 patients scored zero both pre- and post-operatively. Moreover, scores on CUNY sentence tests (sound plus lip-reading) were typically lower than scores seen in post-lingually deaf adults due to the complex linguistic content. BKB sentences are a poor method of evaluating post-operative benefit in this pre-lingually deaf group since auditory-only ability remains limited even with a CI. However additional visual cues are an important component of communication for pre- and peri-lingually deaf patients and so results from CUNY sentences with lip-reading plus sound from the CI suggest this test is a more useful measure than auditory-only open-set speech discrimination.
Since this group is unlikely to achieve auditory-only open-set speech discrimination with a CI, a different test is required to demonstrate any benefit. Measures including subjective benefit and real-life communication may prove more sensitive. Further investigation is underway involving patients themselves to help identify factors both pre- and post-operatively that they feel are important considerations in deciding whether or not to have a CI and then how to measure the benefit they receive.
Conclusions
During the assessment, the MHIP team had concerns about implanting all the patients in this group, as indicated on the APDIP scores. However the level of concern had no apparent predictive value regarding eventual CI use or benefit. Datalogging was highly useful for assessing average daily use and also as a counselling tool to encourage regular use. There was a significant relationship between daily implant use and level of benefit from the CI. The most sensitive measure to assess level of benefit was CUNY sentences presented with lip-reading alone and lip-reading with sound from the CI, although scores tended to be low.
Further investigation using a focus group approach is underway to identify a new measure that is more sensitive in showing the level of benefit pre-lingually profoundly deaf adults gain from their CI (CitationWright et al., 2015). Overall the findings of this study suggest that pre- and peri-lingually profoundly deaf adults do obtain measurable benefit from a CI as demonstrated with CUNY sentences testing and datalogging but additional measures are required to both assess and demonstrate this.
Disclaimer statements
Contributors HC: assisted with statistical analysis. AR: assisted with data analysis. TW: advised on experimental design.
Funding None.
Conflict of interest None.
Ethical approval None.
References
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