Literature
Clinical Pearls & Morning Reports
Published April 15, 2020
Do cochlear implants improve speech perception in all recipients?
Often simply considered one of the stigmata of senescence, hearing loss has become increasingly recognized as an important health issue that may lead to increased risks of social isolation, depression, loss of autonomy, reduced employability, and neurocognitive dysfunction. Read the NEJM Review Article here.
Clinical Pearls
Q: What options are available for adults with hearing loss?
A: The decision to recommend treatment with a cochlear implant is driven by the results of audiometric testing, as well as the demands of the everyday listening environment. A person with limited unilateral hearing loss or mild bilateral high-frequency hearing loss may function reasonably well in a quiet environment. However, people with greater degrees of hearing loss frequently struggle with everyday communication, particularly in the presence of background noise. Fitted hearing aids provide sufficient benefit for most patients who have relatively good speech recognition. However, for patients with poor speech recognition and more advanced bilateral sensorineural hearing loss, cochlear implantation provides the only effective means of auditory rehabilitation currently available. Whereas hearing aids function by amplifying sound, cochlear implants bypass nonfunctional or missing cochlear hair cells and directly stimulate surviving spiral ganglion cells of the distal cochlear nerve, enhancing both audibility and speech recognition.
Q: Is cochlear-implant surgery widely used among eligible adults in the United States?
A: Cochlear implantation is a relatively low-risk outpatient procedure that generally leads to improvements in speech understanding and quality of life. Yet it is estimated that less than 10% of adults in the United States and other developed countries who meet the current criteria for cochlear implantation actually receive this treatment.
Morning Report Questions
Q: Describe some aspects of the use of cochlear implants in adults.
A: External cochlear-implant components have become increasingly miniaturized, and most current designs can be concealed relatively well under medium-length or long hair. Currently, several commercial implant manufacturers are evaluating the safety and feasibility of a totally implantable cochlear-implant system. A totally implantable system not only would render the device virtually invisible but also would support full-time use. The external device is typically removed while the patient is swimming, showering, and sleeping. At most centers, there is a routine delay of 2 to 4 weeks after surgery before the device is turned on. Recently, device activation within 24 hours after surgery was successfully implemented at several centers to expedite rehabilitation and potentially reduce the number of early postoperative return visits. Although the rate at which speech perception improves after cochlear implantation is variable, increases are usually steepest within the first 6 months of use. However, continued progress can be seen up to 3 years after surgery.
Q: Do cochlear implants improve speech perception in all recipients?
A: Although most implant recipients have significant gains in speech perception, a subgroup of recipients have poor outcomes, even after extended use of the implant and supplemental rehabilitation. The duration of deafness before implantation and the preoperative speech-perception scores have the highest predictive value for the speech-perception outcome among adults who have received cochlear implants, whereas age at the time of implantation and the cause of sensorineural hearing loss do not appreciably influence the outcome in most studies. Nevertheless, even the most robust predictive models cannot fully account for the observed range in speech-perception scores. Understanding the complex mechanisms underlying outcome variation and the development of new interventions to successfully remediate poor test performance remain two critical objectives in the field today.