I understand that absent middle ear reflexes, normal otoacoustic emissions and an abnormal or absent auditory brainstem test are all consistencies with auditory neuropathy. However, with comprehensive OAE and reflex testing, do all frequencies tested need to show absent and present results, respectively? For example, if there are some present reflexes and some absent emissions, can you still diagnose this person as having auditory neuropathy (with a corresponding abnormal/absent ABR, that is)?
From the brief description in the question, I would suggest follow-up testing before making a diagnosis of auditory neuropathy (AN). The literature shows that acoustic reflexes are nearly always absent (or elevated), so the presence of some normal reflexes would discourage the diagnosis of auditory neuropathy. The absence of otoacoustic emissions (OAEs) at some frequencies is also not a consistent finding for AN. Having said that, one must always consider that a patient could have two different conditions simultaneously. For example, a patient could have auditory neuropathy and also have noise-induced hearing loss that has damaged the outer hair cells, resulting in some absent OAEs. The patient could have a middle ear condition which would also diminish or abolish OAEs, but acoustic immittance measures (tympanograms and reflexes) should then be consistent with middle ear involvement. Although there have been rare unilateral cases of AN reported, I could locate no data to suggest that within one ear, there would be regions with AN and other frequency regions without AN especially in a child or young adult.
The full picture must be considered, including case history, immittance testing, repeated OAEs, and repeated electrophysiologic measures looking at the cochlear microphonic and ABR. The CM and ABR testing should be done using high intensity (80 dBnHL or higher) clicks with separate runs using condensation and rarefaction to see if the cochlear microphonic reverses polarity, which confirms the hair cell response and distinguishes it from the neural response which does not reverse polarity. A good source on assessment and management of AN can be located at www.nhsp.info/getdata.php?id=146.
Dr. Parent Buck is the Chair of Audiology at the Arizona School of Health Sciences, a Division of A. T. Still University of Health Sciences. She current teaches courses in neurology, embryology, hearing aids and advances in audiologic care. She obtained her Master's Degree in Audiology from Purdue University, and she obtained her Doctor of Audiology degree from Baylor College of Medicine. Dr. Parent Buck has practiced in a variety of clinical settings, provided academic instruction and worked as a sales representative and trainer in the hearing aid industry. She can be reached at email@example.com