In an attempt to improve the criteria for cochlear implants, a group of experts met in 2011 and modified the battery of tests used to determine implant candidacy to better reflect real-world experiences (J Acoust Soc Am. 1994;95:1085–1099; Arch Otolaryngol Head Neck Surg. 2004;130:624–628). The AzBio Sentence Test, which replaced the HINT test, uses both male and female voices speaking in normal cadence and is conducted with and without background noise. “These tests help clinicians quantify the candidates’ functional hearing before implantation, and are also important for measuring post-implant outcomes,” Dr. Blackburn explained.
Explore this issue:November 2017
“There are ongoing studies through the American Cochlear Implant Alliance, where we are working together with CMS to expand their criteria for people with more residual hearing,” said Craig A. Buchman, MD, Lindburg Professor and chair in the department of otolaryngology-head and neck surgery at Washington University School of Medicine in St. Louis.
Most guidelines recommend cochlear implants starting at one year for children with severe bilateral hearing loss, but some centers perform implants earlier (at nine months of age). There is no upper age limit for implantation, according to experts. As long as a patient fits candidacy criteria and is deemed medically fit for general anesthesia and surgery, he or she is considered a candidate. The procedure usually takes between one and two hours, with the patient typically sent home that day. Dr. Tucci recently implanted a 94-year-old man “who is sharp as a tack and doing beautifully.”
A recent study by Mudery and colleagues found that older adults (those with an average age of 73 years) had a 71% improvement in AzBio scores in quiet and a 51% point improvement in noise on the implanted ear. When hearing was measured on both sides, the researchers found bilateral hearing improved 23% points in quiet and 27% points in noise (Otol Neurotol. 2017;38:187-191). They concluded, “All patients undergoing CI candidacy testing should be tested in both quiet and noise conditions. For those who qualify only in noise, our results demonstrate that cochlear implantation typically improves hearing both in quiet and noise.”
Bilateral versus Unilateral CIs
Part of the confusion over the guidelines is whether to place one or two cochlear implants in patients with bilateral hearing loss. Some of these decisions come down to cost.
“The medical profession is very aware of the need for bilateral hearing. We have been saying this for years with regards to hearing aids—you need two ears. But for some reason, it has taken us longer to begin that conversation with cochlear implants,” Dr. Blackburn noted. “There is an auditory perceptual advantage to hearing bilaterally. The brain is more efficient at filtering out background noise when auditory information is received from both sides.”