EMLR as a Potential Objective Measure for Programming Cochlear Implants: Preliminary Results - OMAI 2018- The 10th International Symposium on Objective Measures in Auditory Implants

Ricky Kaplan-Neeman ^1,2 Ricky Kaplan-Neeman ^1,2 Chava Muchnik ^1,2 Minka Hildesheimer ^1,2 Yisgav Shapira ³ Yael Henkin ^1,2

¹Hearing, Speech & Language Center, Sheba Medical Center, Tel Hashomer, Israel
²Department of Communication Disorders, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
³Department of Otolaryngology Head & Neck Surgery, Sheba Medical Center, Tel Hashomer, Israel

The use of objective measures for CI programming in young children and uncooperative CI recipients has been widely described. Particularly, thresholds of electrically evoked compound action potentials (eCAPs) were found to assist in determining initial thresholds (T) and comfortable (C/M) levels. While eCAP is of a peripheral origin, a higher order, more central measure, might provide a better approximation of map T and C/M levels and thus better correlate with auditory behavior. The electrically evoked middle latency response (EMLR) is a physiological response generated in thalamo-cortical pathways, known to reflect neural responsiveness to electrical stimulation. As such, it may serve as an advantageous measure that will assist in CI programming. The objectives of the current study were to assess: 1) The feasibility of recording EMLR in CI recipients using electrical stimulation and a standard AEP recording system; 2) The relation between behavioral T levels and EMLR thresholds.
EMLRs were recorded from postlingual adult CI recipients by means of MedEl`s Maestro 7 software and Biologic Navigator Pro AEP system. EMLRs were elicited by initial stimulation levels that were set approximately 10% higher than M levels, and were reduced to a level at which a visible response was evident at different electrodes along the array.
EMLRs were identified in 50% of tested patients due to electrical artifacts that contaminated the recordings and prevented detection of repeatable responses. EMLRs were similar in morphology to the acoustic counterparts, demonstrating significant amplitude decrease between upper and lower stimulation levels. EMLR thresholds were approximately 20% above behavioral thresholds (T).
These preliminary results support the feasibility of recording EMLR in CI recipients. Further research is needed to establish protocols that will eliminate artifacts and enable the evaluation of the clinical value of EMLR for CI programming.