We recently had a new staff member join our department. He has worked for 16 years at one hospital, under the direction of ENT. Basically, if ENT asked for a test he performed it, no questions asked. He wants us to incorporate SISI and tone decay testing into our retrocochlear battery to differentiate cochlear from retrocochlear hearing losses. I have been practicing for 17 years and have never seen the SISI used nor have I used it myself. We talked about it in school, as well as ABLB, but never used either of them. I have always had access to ABR, reflex testing and reflex decay. I did use tone decay for many years, but never saw it successful in identifying any patients with retrocochlear pathology so discontinued using it. I am wondering what current best practice recommendations are with regard to use of either of these tests. We have ABR and OAE testing at our hospital as well as MRI. Is there any basis for using either of these two tests to assist in the diagnosis of a patient with retrocochlear pathology OR to differentiate sensory from neural hearing loss?
This is not a new question. Audiologists have been challenged with the task of identifying and quantifying hearing loss, and identifying the site of lesion (location) causing a hearing loss since we have been a profession. To this end, numerous tests have been devised, starting with the Alternate Binaural Loudness Balance (ABLB) in 1928. Over the past 80 years, over 40 audiological site of lesion tests (or modifications of other tests) have been reported in the literature. Many of these test procedures are still taught in graduate programs and many are still used clinically. Have these tests persisted over time because they are the best or because individuals have not looked critically at the effectiveness or efficiency of the various tests, particularly in differentiating between cochlear and retrocochlear lesions? Over the years, a number of investigators have addressed this issue. In 1988 there was a book chapter "Clinical Audiology: Using the Test Battery," written by Don W. Worthington in a book called "International Perspectives On Communication Disorders," edited by Sanford E. Gerber and George Mencher, published by Gallaudet University Press. In that chapter, there is a discussion of a decision matrix model suggested by Dr. James Jerger for determining the sensitivity, specificity, predictive value, and efficiency for evaluating audiological tests and determining which tests should be utilized in the clinic. The chapter is a review not of every auditory site-of-lesion test, but rather of those tests that were in frequent clinical use at that time.
On the basis of the review by Worthington and at least 6 other investigators, a group of tests can be selected that are sensitive, specific, and efficient and require a minimum of time to administer. The recommended tests at that time were: auditory brainstem response (ABR), acoustic reflex/reflex decay, tone decay (Olsen-Noffsinger modification), and high-level speech discrimination (PI-PB modification). Clearly, several of the tests that were used at that time in site-of-lesion batteries were neither sensitive nor efficient in the detection of retrocochlear pathology. These were ABLB, Bekesy, and SISI.
One should take the time to review the specific test battery that is used in their clinic, remembering that the goal is to be effective, efficient and cost effective in identifying or localizing a deficit in the auditory system. Also keep in mind, the tests we perform are tests of function and cannot determine the specific pathology. Be sure that you are as critical of new tests and the information that they provide as you determine your site-of-lesion-battery.
Dr. Don W. Worthington has been an audiologist for over 30 years. He is currently the Director of the Intermountain Hearing & Balance Center which is located in Salt Lake City, Utah. He loves the field of Audiology.