4. Cochlear Implants

         Cochlear implants were not considered at first for AN/AD patients because of the suspected abnormality of the eighth nerve, which seemed counterintuitive for cochlear implant management. Given appropriate family and patient history, cochlear implants are a viable management option for AN/AD patients. Children usually show significant improvements in speech perception abilities, communication skills, and sound detection. A few adults with AN/AD have also been implanted.

We now make our decision on a case-by-case basis, looking at the history of the patient and the desires for future outcomes of the patient and family. Not knowing how a patient will develop makes it difficult to offer a single management plan. Therefore, the age of the patient, current language ability, and extent to which the condition is affecting their life should be considered. Implants are not the only management option but rather may be a strong possibility after careful consideration of the individual's background.

5. Changes over time

         Over time, AN/AD may improve, remain unchanged, or become worse. In a few rare cases, the condition seems to have improved over time. In our sample group of 100, seven patients began to develop age appropriate speech and language without amplification, and further intervention was not required for them to function in the hearing and speaking world (Berlin et al., 2001). However, they still no showed no synchronous ABR. Those infants that worsen tend to lose their emissions and become indistinguishable from sensory hearing loss patients. In these cases, early identification can be helpful; it may assist in understanding future behaviors such as sporadic evidence of hearing seen by good prosody, vocal monitoring, word use, awareness to environmental sounds, or a strong rejection of hearing aids.

      Berlin et al. (2001) suggested that AN/AD encompasses a continuum of possible outcomes from living in Deaf culture to only minimal difficulty hearing in noise. AN/AD is not limited to children; adults have also been diagnosed with it, though it is not known if the condition developed late, gradually grew worse, or was present but unidentified since infancy. To date, there is no means to accurately predict which course an AN/AD patient may take, whether improving, remaining the same, or progressively worsening.

The variation in AN/AD is particularly represented in adult patients. Some of those seen at Kresge Lab have been able to manage quite well with visual input such as lip reading, closed captioning or by using their own compensation strategies. Some AN/AD adults obtain success with cochlear implants, while others function well in the Deaf community and use sign language as their primary means of communication. A few patients show only mild functional effects of the AN/AD.

6. Other considerations

         With the development of newborn screening programs many AN/AD patients are identified at a young age. From the sample of 100 AN/AD patients (Berlin et al., 2001), the largest group was two years old or younger. For infants, management can mean watchful waiting. While this can seem frustrating for parents, it is necessary to ensure the best course of action. During the waiting period, visual language in the form of cued speech and some method of signs (e.g., baby signs, signed English, ASL) should be used with the infant to avoid language delays (Berlin et al., 2002).

The watchful waiting period can vary, though a general guideline used at the Kresge Lab is no more than 18-24 months of age. During this time, methods of visual language training are used, and the child should be monitored for presence of emissions, synchrony in the ABR, and development of language. The family should determine what they want for the child's future in terms of functioning in the hearing world.

AN/AD is not limited to the pediatric population. Some patients do not discover that they have AN/AD until later in life when difficulty in school or work is encountered. Some of these patients may also have associated conditions such as Charcot-Marie-Tooth disease, other neurological degenerative conditions, or visual deficits that require careful scrutiny. Current language level and function should be examined in this population. Even though language may develop, our experience is that AN/AD patients have little or minimal word or sentence recognition in the presence of competing noise. This can have a significant effect on educational and vocational achievement.

7. Conclusions

         The evolution of AN/AD continues to present a challenge to audiologists and other professionals because there are many variables to consider in its diagnosis and management. Rather than one path, AN/AD presents many facets and several possible outcomes for patients. The use of physiologic tests, MEMRs, ABR, OAEs, are critical to an accurate diagnosis. Age is not a limiting factor in the identification of new AN/AD patients. Rather than treating the audiogram, audiologists should match the management with the physiology and the needs of the patient and the family. This may mean not recommending hearing aids even though the audiogram might suggest that they are appropriate. In terms of outcome, there are many variations on the theme of AN/AD, which complicates the choices that families must make. Options should be explored based on patient history, including birth history and the possibility of peripheral neuropathy, and whether there is a desire to enter the hearing and speaking world. Cochlear implants have been found to be successful in many patients with AN/AD, and are one, though not the only, option. With the proliferation of screening programs using ABR, the detection of AN/AD is likely to increase markedly. Therefore we recommend watchful waiting so long as the patient's speech and language develops on target.

8. References

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