Interview with Chris Hoffman Director of Audiology, Ear Specialty Group, Springfield, New Jersey

Topic: Auditory Neuropathy
AO/Beck: Hi Chris. Thanks for joining me today. I'd like to start with a brief review of your professional history and education and then we'll get into the topic of the day - auditory neuropathy.

Hoffman: Sure, that's fine. My undergraduate degree was in audiology and speech at Stockton State College in South Jersey I then received my graduate degree (MS) in Educational Audiology, from Penn State in 1986. I went right into my CFY and had been practicing audiology since.

AO/Beck: OK, well that was indeed a brief review! Please tell me the name and location of the practice you're with currently?

Hoffman: Since 1996, I have worked at Ear Specialty Group. There are 2 office locations, one in Springfield, NJ and the other in Paramus, NJ. The group is basically an otology and neuro-otology practice. I work with two otologists, Drs. Jed Kwartler and Avrim Eden. There are also 2 other full time and 2 part time audiologists.

AO/Beck: From my earlier discussions with Dr. Kwartler, I recall that you guys have a fairly busy cochlear implant practice?

Hoffman: Right. I would say that the majority of my time is spent working with cochlear implant patients.

AO/Beck: Primarily children or adults?

Hoffman: A mix, it's about 50-50.

AO/Beck: Okay, great. With that as background, let's get into Auditory Neuropathy (AN), and by the way, the other name for AN is auditory dys-synchrony, right?

Hoffman: Yes, the names are used interchangeably.

AO/Beck: Let's start with the working definition of auditory neuropathy. What is it and how do you diagnose it?

Hoffman: I consider auditory neuropathy a dys-synchrony in the auditory mechanism. In essence, AN indicates that information from the cochlea is not being transmitted in an efficient manner along the auditory pathway. The term AN was probably first used by Yvonne Sininger et al in 1995. Dr.Arnold Starr described the electrophysiologic and psychoacoustic findings in 1991.

AO/Beck: Okay. So, you're saying there is some physiologic interruption or distortion between the cochlea and the temporal lobe?

Hoffman: Correct.

AO/Beck: Is there a specific anatomic site that correlates with AN?

Hoffman: I'm not familiar with any specific site. The closest we can offer is that it's along the auditory pathway and can cause different symptoms across different patients. Dr. Arnold Starr has reported that possible sites could occur within the nerve itself, at the synapse or at the inner hair cell level.

AO/Beck: All right. What are the red flags that makes one think, Ahh, this might be auditory neuropathy. What do you look for in an ABR and OAE?

Hoffman: What we typically see in young children, are present and robust OAE's and absent middle ear reflexes and ABR responses and lack of benefit from conventional amplification.

AO/Beck: And we know that normal OAEs indicates that hearing at the level of the peripheral nervous system is better than 25 or 30 dB HL and of course in that situation you would expect a normal ABR?

Hoffman: Correct.

AO/Beck: Why would you do an ABR on somebody with normal OAEs?

Hoffman: Let's use an example of a newborn. Suppose they pass the OAE screening in the hospital. However, as they develop they may not demonstrate expected developmental milestones; such as responding or startling to sound, localization of sound etc. At that point, the parents or their physicians will refer to us, and that's typically when we'll do the ABR and other behavioral tests with those children.

AO/Beck: Okay. So now we have a normal OAE, we have an absent or poor morphology on an ABR, and where do we go from there? Does that instantly make the diagnosis or must there be radiologic studies?

Hoffman: Generally our patients will go through a battery of tests including; radiologic studies, blood work, in-depth medical evaluations, and in-depth objective and subjective audiologic evaluations too.

AO/Beck: So in some respects this is a diagnosis based on exclusion? In other words, there is a recognizable diagnostic pattern, and nothing else fits?

Hoffman: Correct. AN is diagnosed after we've tried everything, and nothing else makes sense!

AO/Beck: I can recall some controversy regarding children with auditory neuropathy and whether or not to put hearing aids on them and whether or not to proceed with cochlear implants?

Hoffman: I think there is always going to be a controversy when we're discussing children! I believe we all have the child's best interest at heart and there's just going to be differing opinions, which I think of as a strength, rather than as a shortcoming! It forces us to work together, and evaluate all the available information before deciding on any course of action when it is related to children. When dealing with any patient, and especially children, we (as audiologists) will take the least invasive approach as possible.

With children, there is a fear of not providing adequate auditory/linguistic information during the critical language learning period. The first step is to appropriately fit the patient with hearing aid(s). If no significant change or improvement in auditory awareness or development is seen by an evaluation team (including; audiologists, physicians, educators and parents), then the option for cochlear implantation is considered.

Today, I worked with a patient who was seen for the second day of initial stimulation with her cochlear implant. The child was diagnosed at another facility with auditory neuropathy at approximately 12 months of age. She was subsequently fitted with 2 hearing aids. After a period of approx. 6 months of consistent amplification, no objective or subjective change was seen in her auditory awareness. Following input from the evaluation team, it was decided to pursue cochlear implantation. She was implanted at 18 months and she is now 20 months old. During her mapping session today, for the first time, she had very consistent responses to auditory stimulation using play audiometric techniques. She was able to stack blocks and throw a toy in a bucket whenever she heard a beeping sound. She even imitated some nonsense syllables such as ba-ba when no visual clue was given!

AO/Beck: OK. What can you tell me about her pre-op hearing?

Hoffman: She was presenting with no responses to sound.

AO/Beck: Okay, so this is not a child with normal OAEs?

Hoffman: Well, interestingly, she had OAEs, but her behavioral response was really not there, there was no behavioral response to auditory stimulation -- but she did have present and robust OAE.

AO/Beck: So, if this child were ten years old, what do you suspect her audiogram would look like?

Hoffman: She would probably present with either a corner audiogram or no response at all to sound.

AO/Beck: So then why does she have present OAEs?

Hoffman: Because the peripheral auditory nervous system is working, it's just that the information beyond the cochlea is not able to efficiently transmit the information through the auditory pathways to the auditory cortex to hear the sound.

AO/Beck: Here's a difficult question - Do you think some of the children that have auditory neuropathy and get cochlear implants, might eventually have presented with normal, or near-normal hearing after they aged a few more years?

Hoffman: That is a good question. I haven't had much experience with that age group with auditory neuropathy yet. I have spoken with other professionals and there have been some children that might present with fluctuating hearing loss, where sometimes they might show a mild to moderate hearing loss and sometimes severe, sometimes even close to normal. Nonetheless, I am not aware of any AN patient who didn't respond to sound, and then later presented with normal hearing. I'm not saying it doesn't happen, but I haven't heard of it.

Keep in mind that all patients go through a rigorous evaluation before cochlear implant candidacy is determined. If a child presents with fluctuating hearing loss, or mild to moderate hearing loss and/or is acquiring speech and language in an expected rate, he/she would not be considered a cochlear implant candidate.

AO/Beck: How many AN children have you implanted?

Hoffman: We're just now working with our second cochlear implant patient with auditory neuropathy.

AO/Beck: What are your thoughts as far as rehab and as far as long-term outcomes for the implanted child with AN?

Hoffman: Some research has indicated that with the use of a synchronous signal via the cochlear implant, we are helping make the auditory system synchronous so auditory information can be processed in a meaningful manner. Theoretically, if implanted early enough, such as the child we saw today, they will very likely be able to develop speech and language along age appropriate milestones.

AO/Beck: Has anybody ever looked at outcomes of perhaps three kids with AN who've been implanted versus three kids with AN who received hearing aids, versus three kids who did not receive hearing aids or implants - and do we really know there's a significant difference in these kids?

Hoffman: Jon Shallop, Ph.D. and his team at the Mayo Clinic presented a Pre-Conference Symposium-Pediatric Panel and another seminar, Auditory Neuropathy and Cochlear Implants: an Update at AAA last April (2002) in Philadelphia. During the Pediatric Panel, they presented several case studies. Both seminars also reviewed research they have conducted regarding cochlear implants and patients/children with auditory neuropathy. Their test group included only AN children. The Control group subjects were non- AN children matched by age, duration of deafness before initial stimulation of the implant, and age at initial stimulation of the implant.

Results indicated that the AN children had slightly better hearing thresholds than the controls both pre- and post- operatively. Post operative evoked potentials showed significantly improved neural synchrony in the AN patients. In addition, both pre- and post-operatively, there was no difference in auditory behavior between the AN and the non-AN children. Most importantly, significant improvement in speech perception data was seen for both groups with the cochlear implant independent of the etiology.

Some of the case studies presented by Dr. Shallop also showed significant improvement in speech perception and language testing results over time for their AN patients with cochlear implants.

There are some very good references on AN. Here are a few:

Hood, LJ Auditory Neuropathy/auditory dys-synchrony: New insights. The Hearing Journal. February, 2002

Shallop, J et. al., Cochlear Implants in Five Cases of Auditory Neuropathy: Postoperative Findings and Progress. Laryngoscope 2001

Berlin, C. et al., On renaming auditory neuropathy as auditory dys-synchrony, Audiology Today. 2001

AO/Beck: How do you proceed with Aural Rehabilitation for these children?

Hoffman: All patients should be placed in an educational environment that emphasizes auditory/oral skills. Typically, with very young children it's introducing sound stimulation in an enriched language and sound environment, as well as auditory training with either an auditory verbal therapist (AVT) or speech language pathologist. With the adult I'm working with now, she is working with a speech language pathologist and pursuing working with an AVT. She's also an audiology student getting her doctorate in Audiology. She is following up in a structured setting learning how to use this auditory information and she's finding it quite beneficial. Pre-implant to post-implant comparisons show that her word recognition and sentence recognition scores have increased tremendously.

AO/Beck: Thanks so much for your time and knowledge. I appreciate your help.

Hoffman: Thank you too Doug. It's been a lot of fun for me too.


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