Pre-attentive auditory responses in multiple sclerosis patients

Abstract

Background :MS is characterized by impairment in cognitive domains. Sensory memory is one of the cognitive domains affected in MS. MMN allows the brain to detect (via a comparator mechanism) deviant events occurring within a stream of repetitive stimuli. The amplitude and latency of the MMN has been used to elucidate the nature of the sensory memory upon which it is based. Aim: This work was designed to evaluate and measure the MMN test results as regard its amplitude and latency in MS patients and to compare the results with normal age and gender matched control group in an attempt to declare the diagnostic and prognostic value of MMN in MS patients. Methods : Forty patients with multiple sclerosis (MS) were diagnosed and referred from the Neurology department. All participants in this study (forty MS patients and forty healthy subjects' sex and age-matched with MS patients) were subjected to basic audiological evaluation, mismatch negativity (MMN) recording using oddball paradigm with frequency variation, and Expanded disability status scale (EDSS) for MS patients. MMN amplitude and latency were measured in both MS patients and control subjects. MMN results were compared to MS and healthy control. Also, EDSS was measured in MS patients. The forty MS patients are divided into two subgroups: MS patients who produced an MMN wave and MS with absent MMN compared to the demographic data of both subsets. Results: A significant difference between the two subgroups in the duration of MS diagnosis was present. Also, there was a substantial difference between groups in sex. The subgroup with absent MMS was all male. Meanwhile, no considerable difference between both groups as regards age and EDSS. There is no difference in MMN latency and amplitude between MS patients with preserved MMN and control groups. Twenty percent of our MS patients have absent MMN, which is all-male reflecting cognitive impairment, cognitive fatigue, or central processing disorders. In contrast, there is no difference in latency and amplitude between recorded MMN in the study and control groups. Conclusions: The absence of MMN in some MS patients suggests affection of the central auditory processing abilities measured by MMN in those patients which need further research