Eye movements in relation to rhythmic masticatory muscle activities in patients with sleep bruxism

Objectives: To characterize eye movements during rhythmic masticatory muscle activities (RMMAs) in patients with sleep bruxism (SB).

Methods: Polysomnographic (PSG) recordings were performed on SB patients and normal controls during sleep (n = 8 for each group) and wakefulness (n = 9 for each group). The eye movements associated with episodes of RMMAs/SB during sleep and jaw movements during wakefulness were analyzed.

Results: During sleep, all episodes of RMMAs/SB in the SB patients and controls were associated with eye movements and most of the RMMAs/SB related slow eye movements (SB patients: 96.29%, 1583/1644; Controls: 97.49%, 543/557) were horizontal in the SB patients and controls. During wakefulness, all of the series of jaw movements were associated with eye movements. Most of cycles of jaw movements (SB patients: 88.89%, 200/225; Controls: 95.11%, 214/225) were associated with slow eye movements and most of the eye movements (SB patients: 52.50%, 105/200; Controls: 61.21%, 131/214) were vertical. There were significant correlations between the durations of episodes of eye movements and RMMAs/SB during sleep and between the duration of episodes of eye movements and duration of series of jaw movements during wakefulness in the SB patients and controls.

Conclusions: Most of RMMAs/SB episodes during sleep and jaw movements during wakefulness are associated with eye movements in SB patients and normal controls.