Evaluation of brainstem reflex in bruxism cases

Bruxism is a parafunction and reported to be %8 as sleep bruxism, %20 as awake type by the adult population. It has been accepted to be as a result of occlusal disturbances and mechanical problems of the masticatory system in the sixties, but the central influences such as autonomic, dopaminergic, hormonal changes and sleep arousals seems to be more prominent in recent years. The blink and the MIR (masseter inbitory reflex) studies are the neurophysiologic examinations to research functional relations of the brainstem neuronal pathways. In this study, a total of 36 subjects diagnosed with bruxism on the basis of self reports and 36 controls have been investigated to find any difference between the two groups. The participants have been given the BECK depression and physiological tests for anxiety. The MIR and blink reflexes studied by TMS and electric stimulation. The cortical silent period evoked in contralateral masseter muscle by TMS. Central motor conducting times were evaluated. The absence of SP2 (component of MIR), R2 (component of blink reflex) latency and left APB (abductor pollicis brevis) muscle F wave latency are found to be significantly different between two groups. These results support the view that bruxism is mainly centrally that involves subcortical (brainstem) structures.