***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective : Compare results of cochlear implantation in younger and older adults in the domains of disability and h and icap , as well as in tests of word recognition and localization , across unilateral implant ( CI ) , bilateral ( CI + CI ) , and CI with an acoustic hearing aid in the nonimplanted ear ( CI + HA ) . Design : Three parts : retrospective ( postimplant only ) analysis ; prospect i ve ( preimplant versus postimplant ) ; correlation between age and benefit from CI versus CI + CI .  Two age groups , older and younger than 60 years , for the first 2 analyses ; age is a continuous variable for the third analysis . Setting : Tertiary referral hospital clinic . Patients : Postlingually severely-to-profoundly hearing-impaired adults : Totals of 68 CI , 36 CI + CI , and 38 CI + HA in the retrospective part of the study ; totals of 30 CI , 18 CI + CI , and 16 CI + HA in the prospect i ve parts . Numbers vary from these totals on individual measures . Interventions : Patients receive either 1 or 2 cochlear implants ; some with 1 CI opt to retain a hearing aid in the nonimplanted ear . Outcome Measures : Principal measures : Hearing H and icap Inventory for the Elderly , Hearing H and icap Question naire , Speech , Spatial and Qualities of Hearing Scale , word recognition test , and soundfield localization test . The study is exploratory , but proceeding from a null hypothesis of no expected contrast as a function of patient age . Results : All patient groups show significant benefit after implantation . No significant age-related differences are observed in patients with unilateral implant , nor in CI + HA group . In the CI + CI group , the younger cohort showed very substantial increases in both performance and self-rated abilities ; the older cohort provides more mixed outcomes . Conclusion : Results for the CI group confirm and extend earlier research . The result for the younger group of CI + CI patients demonstrates the consistent incremental benefit obtained from a bilateral procedure . The mixed outcome observed in the older CI + CI group might be due to individual differences in interaction between effects of aging and the ability to integrate binaural cues Objective : The purpose of the study was to investigate sound localization with bilateral and unilateral cochlear implants . Design : Sound localization tests were performed on 20 bilaterally implanted MED-EL COMBI 40/40 + users . All subjects were bilaterally implanted during adolescence or later .  Sound localization was tested in the frontal horizontal plane by using 9 equally spaced loudspeakers and speech-shaped noise bursts at r and omized levels . Results : The group of subjects who were bilaterally deafened after 5 to 6 yr of age ( 18 subjects ) showed a statistically significant improvement in sound localization when using both implants , compared with when using only one . The mean deviation between the presentation azimuth and the response azimuth was 16.6 ° when using both implants , which was on average 37.1 ° smaller than when using one implant only . When adjusted for the localization error that was constant across loudspeakers , the mean deviation was 15.9 ° for bilateral implant use , representing an improvement of 30.1 ° over unilateral implant use . Statistical analysis showed that in this group , performance measures were not correlated with subject details such as age at onset of deafness or duration of unilateral implant use . In contrast , subjects who were bilaterally deafened before 6 yr of age ( 2 subjects ) did not show a benefit in sound localization from bilateral implants . Conclusions : Bilateral cochlear implants offer a substantial benefit in sound localization to late-deafened , late-implanted subjects . The very limited data from early-deafened subjects implanted at a later age could suggest that these subjects may not benefit in sound localization from bilateral cochlear implants . It is possible that early implantation for early deafened subjects might allow better acquisition of spatial hearing , thus leading to improved localization performance OBJECTIVES To evaluate sound and speech perception and quality of life in prelingually deafened adults implanted with state of the art devices .  To investigate which patient factors influence postoperative performance . STUDY DESIGN Prospect i ve intervention study . METHODS Eight prelingually deafened subjects ( with onset of severe hearing impairment before the age of 4 years and functioning in an oral-aural setting ) participated in this study . Subjects were implanted at a mean age of 36 ( range , 21 - 55 ) years with a CII or 90 K cochlear implant ( Advanced Bionics Corp. ) . All subjects completed  st and ard speech perception tests as well as quality of life measures ( Health Utility Index Mark-II , Nijmegen Cochlear Implant Question naire , visual analogue scale for subject 's hearing and health ) at different points in time . Postoperative scores were compared with each other and with the baseline preoperative scores . The relationship between nine patient variables and the postoperative consonant-vowel-consonant ( CVC ) phoneme score was also investigated . RESULTS Significant improvement was measured for CVC word and phoneme scores and several quality of life measures . Postoperative speech perception correlated with a new and promising factor named quality of a patient 's own speech production ( QoSP ) . CONCLUSION With state of the art implants , speech perception and quality of life do improve in prelingually deafened adults . More importantly , the prognostic value of QoSP should be investigated further Objective : Preliminary studies show that bilateral cochlear implantation improves speech-recognition ability in many subjects ; however , the magnitude of this improvement has been variable . The objective of our research was to explore means to better differentiate the binaural benefit that many patients who receive bilateral cochlear implants ( CIs )  describe . Hypothesis : Binaural improvements in speech-perception performance will be consistently evident across patients when they are tested in more challenging listening situations . Design : This was a prospect i ve clinical study . Speech-perception performance was compared between the unilateral and bilateral cochlear implant conditions . Because the purpose was to investigate testing parameters that would demonstrate binaural benefit , word- and sentence-recognition tests were administered under several stimulation conditions : with and without noise and at three presentation levels . In addition , all subjects completed the Abbreviated Profile of Hearing Aid Benefit as a measure of subjective benefit . Subjects were adult cochlear implant recipients . Three device manufacturers were represented ( Advanced Bionics Corporation , Cochlear Americas , and the Med-El Corporation ) ; three patients received simultaneous implantation , and the other four patients received sequential CIs . The setting was a comprehensive cochlear implant program/tertiary referral center . The main outcomes measures were speech-recognition scores in percent correct , mean score difference for unilateral versus bilateral conditions , and subjective benefit scores . Results : The most significant improvements in  binaural cochlear implant use were found when subjects were tested with sentence material presented at 60 dB SPL with a + 8 dB signal-to-noise ratio . Six of seven subjects showed significant binaural improvement , with a mean improvement score of 12.43 % ( SD = 5.32 ) . All subjects preferred the binaural listening condition . Measured improvements in quality of life were seen . Conclusions : Preliminary study findings suggest that significant cochlear implant binaural benefit in speech perception may be observed when testing in more difficult listening situations ( i.e. , lower presentation levels and in noise ) . According to the outcome of our study , testing the binaural benefit of CIs requires consideration of suitable test material s and stimulation parameters OBJECTIVE To present the results of a survey administered to a group of early-deafened cochlear implants adults and to report the level of perceived benefit . DESIGN Prospect i ve . SETTING Large tertiary referral centre . METHOD A 47-item question naire design ed to evaluate cochlear implant use and benefit was sent to 42 early-deafened adult cochlear implant users . The question naire can be divided into seven subcategories : time of use , associated symptoms , communication , employment status and function , socialization , perceived benefit , and the impact on quality of life . Responses from 30 patients were received . RESULTS The majority of our patients use their cochlear implant all of their waking hours . The majority of patients continue to depend on lip-reading and hearing as their main mode of communication , although they reported improved lip-reading skills with their cochlear implant . Twenty-three patients ( 76.7 % ) were employed . Eleven patients had a change in employment subsequent to cochlear implantation , nine ( 81.8 % ) of whom attributed this to their cochlear implant . Our patients als reported greater independence , a greater sense of safety in their environment , and an improved social life . Twenty-nine patients ( 96.7 % ) said that they were satisfied with their implant , 28 ( 93.3 % ) said that they would go through the same process again , and 27 ( 90 % ) said that they would recommend it to a friend in a similar situation . Twenty-nine patients ( 96.7 % ) stated that the cochlear implant has had a positive effect on their quality of life . Family and peer support , prior auditory-verbal therapy , and a positive attitude were the most commonly cited factors in successful cochlear implant use . CONCLUSIONS Early-deafened adult cochlear implant users perceive significant benefit from cochlear implantation . Importantly , family and peer support , prior auditory-verbal therapy , and a positive attitude are considered important factors in maximizing this benefit Cochlear implants are indicated for elderly patients with severe-to-profound hearing loss ( sensorineural hearing loss ≥ 70 dB ) . Their use has been limited , possibly by the misconception that elderly patients will perform poorly . To document the performance of older adults ( ≥65 years old ) , we undertook a retrospective analysis of our postlingually deafened adult patients who underwent implantation with the CLARION Multi- Strategy Cochlear Implant  and underwent formal audiologic analysis ( sentence recognition [ Central Institute for the Deaf , CID ] and monosyllabic word recognition [ consonant-noun-consonant , CNC ] ) . Both younger ( n = 20 ; mean age = 46.9 years ) and older ( n = 16 ; mean age = 71.5 years ) adults showed statistically significant increases in CID and CNC scores  after cochlear implantation . No statistically significant difference could be detected in operative time , anesthesia time , length of hospitalization , or CID or CNC scores between the two age groups . We conclude that age should not be a criterion for deciding who should receive cochlear implants . ( Otolaryngol Head Neck Surg 2000;123:419 - 24 . Objective : The purpose of this 4-year longitudinal study was to assess the stability of the binaural benefits of head shadow , summation , and squelch for bilateral cochlear implant recipients and to quantify these benefits for the underst and ing of speech in noise . Design : This is a prospect i ve study of 9 patients who received simultaneous bilateral insertion of MED-EL COMBI + 40 cochlear implants in a single-stage operation at the University of North Carolina , Chapel Hill , NC . Each patient had postlingual deafness of short duration before insertion of the device . Each year , the patients were tested for word recognition using consonant-nucleus-consonant words in quiet and speech perception in noise using City University of New York sentences . These tests were administered using direct audio input to the implants . Head-related transfer functions were used to simulate speech in noise testing in a spatial environment . Speech was always presented at midline ( 0 ° ) , and the noise masker was presented at either side or midline ( −90 , 0 , + 90 degrees ) . Results : The binaural benefits of head shadow and summation effects developed early in the postoperative period and remained stable throughout the follow-up period . Squelch developed more slowly and was first demonstrated at 12 months after implantation but continued to increase beyond the first year of follow-up . Conclusion : Benefits of head shadow and summation emerge early and remain stable . However , squelch has the most protracted period of development , with increasing benefit after a year or more of implant experience . These data support the idea that binaural integration continues several years after insertion of bilateral cochlear implant devices Objective : To evaluate speech performance , in quiet and noise , and localization ability in adult patients who had undergone bilateral and simultaneous implantation .  Study Design : Prospect i ve multi-center study . Methods : Twenty-seven adult patients with profound or total hearing loss were bilaterally implanted in a single-stage procedure , and simultaneously activated ( Med-El , Combi 40/40 + ) . Subjects were assessed before implantation and at 3 , 6 and 12 months after switch-on . Speech perception tests in monaural and binaural conditions were performed in quiet and in noise using disyllabic words , with speech coming from the front and a cocktail party background noise coming from 5 loudspeakers . Sound localization measurements were also performed in background noise coming from 5 loudspeakers positioned from –90 ° to + 90 ° azimuth in the horizontal plane , and using a speech stimulus . Results : There was a bilateral advantage at 12 months in quiet ( 77 ± 5.0 % in bilateral condition , 67 ± 5.3 % for the better ear , p < 0.005 ) and in noise ( signal-to-noise ratio + 15 dB : 63 ± 5.9 % in bilateral condition , 55 ± 6.9 % for the better ear , p < 0.05 ) . Considering unilateral speech scores recorded in quiet at 12 months , subjects were categorized as ‘ good performers ’ ( speech comprehension score ≥60 % for the better ear , n = 19 ) and ‘ poor performers ’ ( n = 8) . Subjects were also categorized as ‘ asymmetrical ’ ( difference between their 2 unilateral speech scores ≥ 
    Output:
    
With regard to CI in elderly patients , the selected studies document an improvement of the quality of life and perceptive abilities after CI , even if the benefits were found to be inferior in patients over 70 years at the time of surgery .
Thus , from the results of the studies included in the review , advanced age is not a contraindication for the CI procedure .
With respect to unilateral CI , bilateral CI offers advantages in hearing in noise , in sound localization and less during hearing in a silent environment .
However , high interindividual variability is reported in terms of benefits from the second implant .
With regard to CI in prelingually deaf adults , the selected studies document benefits deriving from the CI procedure in terms of improvement of perceptive abilities and in the quality of life after CI , as well as subjectively perceived benefits .