Sleep bruxism events: an epiphenomenon of severe obstructive sleep apnea?

Objectives: This study investigated the temporal relationships between apnea-hypopnea (AH) and sleep bruxism (SB) events and correlated SB to various respiratory/sleep indexes in adult patients with concomitant obstructive sleep apnea (OSA) and SB.

Materials And Methods: Nocturnal PSG data of 147 consecutive OSA patients were examined for comorbid SB. Among the 49 subjects with coexisting OSA and SB, 26 were randomly selected for in-depth appraisal of temporal patterns which were classified as T1 (unrelated activities), T2 (AH events occur before SB events), T3 (SB events occur before AH events), and T4 (AH and SB events occur simultaneously). Data were analyzed using Mann-Whitney U tests and Spearman's correlation (α = 0.05).

Results: The majority (84.5%) of AH events were unrelated to SB events. Of the 15.5% of related activities, T2 and T3 patterns occurred in 14.1% and 1.4%, respectively. SB events/index, the percentage of unrelated/related AH-SB events, and T2-T3 episodes were not associated with gender, age, body mass (BMI), and apnea-hypopnea (AHI) index. SB events were related to total sleep time (r = 0.44), but no significant associations were discerned between SB and AH index.

Conclusions: As most AH events were unrelated to SB events, OSA and SB are probably epiphenomena in adult patients with concomitant conditions. Where AH-SB events were related, the T2 temporal pattern, where SB events were subsequent to AH events, featured predominantly alluding to a specific form of secondary SB triggered by sleep micro-arousals.

Clinical Relevance: AH and SB events are probably epiphenomena in adult patients with coexisting OSA and SB. Even so, OSA patients should be routinely screened for SB and vice versa considering their frequent comorbidity.