ID 339 – Increases and decreases of power of EEG mu rhythm in patients with amyotrophic lateral sclerosis

Objective EEG mu rhythm is generated over the sensorimotor cortical regions. There are few reports of the decrease of its power in patients with amyotrophic lateral sclerosis (ALS). Our aim was to evaluate whether this can be used as a disease marker. Methods Seventeen ALS patients were compared to healthy controls. EEG was recorded in supine position with eyes closed. Three consecutive EEGs (every 3 months) were recorded in twelve of the patients. Power analysis was performed and log transformed data was statistically analyzed using ANOVA. Results Mu rhythm power was significantly increased in patients compared to controls. Repeated measures ANOVA with post-hoc testing showed significant differences between 1st and 3rd, and 2nd and 3rd EEG recording in patients with decrease of mu power over time. Conclusions Based on previous studies, we expected power decrease of EEG mu rhythm in ALS patients but we observed an increase compared to controls and gradual decrease in patients over time. This could be due to interplay of compensatory mechanisms early in disease and cell loss in the sensorimotor cortex and thalamus with disease progression. Key message The power of EEG mu rhythm is increased in ALS patients compared to controls and gradually decreases over time. This may be a consequence of two mechanisms.