Mismatch Negativity As An Objective Tool For The Assessment Of Cognitive Function In Subjects With Unilateral Severe To Profound Sensorineural Hearing Loss

Abstract

Plasticity has been proved to occur in the auditory system. Subject with UHL provides an opportunity to assess auditory plasticity as a sequence to monaural deprivation. Mismatch negativity is considered to be the best available physiological measure of automatic central processing in audition. The aim of this study was investigating the effect of UHL on cognitive function of the CANS and whether this effect depends on the side of UHL. This was done by studying MMN in response to speech and tone stimuli in normal hearing subjects (control) and subjects with UHL which was further divided into two subgroup according to the laterality of UHL: right UHL (LES) or left UHL (RES). RES and LES subgroups were further divided according to the age of onset ofUHL and according to the duration.ofUHL. Results of the current work revealed that on using speech stimuli, MMN response was better in the right ear than in the left in normal hearing subjects and MMN was affected in cases with both right and left UHL subgroup when compared to control. According to the age of onset of UHL, speech processing was affected whether the UHL occurred before or after the age of full Arabic language acquisition. However, on using tone stimuli, there was no significant difference between right and left ears of the control and in cases with right and left UHL. Moreover, MMN response was also affected by the duration of UHL.