Somatosensory mismatch negativity in Dravet Syndrome

Objective: In early development of patients with Dravet syndrome (DS) there is evidence of a defect in visual and verbal auditory sensorimotor integration (Battaglia et al, 2016). On the other hand, an impairment of motor coordination and postural disorders (clumsiness, crouch gait) is frequently observed, especially in older ages, so much to suggest a possible cerebellar mechanism underlying neurological and neuropsychological features in DS (Battaglia et al, 2013). To investigate also on the somatosensory citcuits, we performed a study on somatic mismatch negativity (sMMN) in 12 children with DS. Methods: Twelve patients with Dravet syndrome aged between 8 and 29 years (median: 15 years) were enrolled in the study. Ten of them showed a SCN1A mutation. sMMN was performed at least twice in all cases according to the oddball stimulation of the protocol used by Restuccia et al. (2007). Frequent and deviant electrical stimulations were delivered via ring electrodes to the first and fifth left finger. Similarly, sMMN was performed in 12 controls with the same age range. Results: In all patients with DS, “oddball” stimulation was not able to elicit normal parietal and frontal extra-negativity. Conclusion: The abnormality of MMN following a somatosensory stimulation in patients with DS would suggest a disorder in mechanisms of detection of sequence deviation, considered cerebellar in origin (Molinari et al, 2008). That is consistent with other experimental (Kalume et al,2007) and clinical (Battaglia et al, 2013) findings that emphasize cerebellar abnormalities in DS. Results of our study may highlight mechanisms underlying neurological and neuropsychological features in DS including sensory motor integration of somesthesia inputs besides visual and auditory ones.