Companion of oral movements with limb movements in patients with sleep bruxism: preliminary findings.

BACKGROUND: Sleep bruxism (SB) patients show a higher incidence of leg movements than normal subjects.

STUDY OBJECTIVES: The study aimed to characterize SB episodes and their relationships with limb movements (LMs).

MATERIALS AND METHODS: Polysomnographic (PSG) recordings were performed on eight SB patients. The intervals between the onsets of adjacent SB episodes and LMs were determined and linear correlation analyses were used to estimate the relationship between the SB index and SB episodes in clusters. The Pearson χ2 and partitions of χ2 tests were used to analyze the differences in incidence of SB episodes and clusters in different sleep stages.

RESULTS: A majority of SB episodes (85.05%) were found to be accompanied by LMs and among them, 70.52% SB episodes occurred with movements of both upper and lower limbs and most of LMs (70.54%) occurred before the onset of SB episodes. Most of SB episodes especially those accompanied by LMs occurred with microarousals or awakenings. Linear correlation analysis showed a positive correlation between the SB index and SB episodes in clusters (r2  = 0.7027, P = 0.0093). In addition, the percentage of SB episodes in clusters accompanied by LMs was significantly smaller than that of SB episodes not accompanied by LMs (χ2 test, P < 0.001) and the percentage of SB episodes in clusters during REM sleep was significantly smaller than that during NREM sleep (χ2 test, P < 0.0001).

CONCLUSIONS: Most SB episodes might not be isolated events, but rather a part of a series of movements second to changes in arousal level.