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Título

RHYTHMIC MASTICATORY MUSCLE ACTIVITY (RMMA) INDEX DOES NOT DECREASE WITH AGE, CONVERSELY TO SELF REPORTS OF SLEEP BRUXISM: DATA FROM SLEEP LABORATORIES OF 3 CONTINENTS

Introdução

Prevalence of Sleep bruxism (SB) self-report decrease with age. There are no studies assessing prevalence of rhythmic masticatory muscle activity index (RMMA)/hr, one of the SB biomarker scored on PSG. We hypothesize the RMMA index will follow the same trajectory as self-reports.

Objetivo

Describe the RMMA prevalence according to age in clinical and epidemiological populations of three sleep laboratories.

Métodos

Retrospective analyses of PSG-RMMA sleep laboratory data were collected in 3 centers (Montreal, Canada; Osaka, Japan; Sao Paulo, Brazil). SB subjects (18-70 y.o.) were recruited: for experimental-physiological studies (Montreal, Osaka (M&O sample)), and from a general representative population sample (Sao Paulo-EPISONO study (SP sample)). The n was 428 subjects: 159 SB and 169 controls. PSG data from second night in M&O sample and first night in SP sample were analyzed. RMMA episodes were scored based on AASM criteria. Distribution of RMMA/h, below/over 40 yo. were analyzed with linear regression according to cut off index (< and => 2/hr) for control and SB subjects. Analyses were done: with clinical diagnosis (+ tooth grinding history & PSG) and only with PSG cut off RMMA index.

Resultados

Data from M&O sample revealed decrease in RMMA index prevailing in subjects below 40 yo. with the Pearson analysis for SB subjects (R2=0.048, p=0.015; explaining 4.8% of variability) and with a decrease Spearman for both controls and SB subjects (Rho=-0.249, p=0.009; Rho=-0.193, p=0.03). The overall age analysis did not reveal any global decrease in RMMA index for either control and SB subjects with Pearson analysis, although a significant but marginal decrease with Spearman for controls only was seen (Rho=-0.287, p< 0.001).
Taking in consideration the PSG RMMA index cut-off alone, < 2 or =>2:
- In the M&O sample, a mild drop in RMMA index for all ages for the < 2 group was significant (R2=0.085, p< 0.001; Rho: -0.34, p< 0.001), which explains 8.5% of variability in RMMA index drop (0.8 to 0.3 RMMA/h from 20 to 60 yo.). This effect was again positioned in the group below 40 yo. (Rho=-0.264, p=0.01). With the RMMA/hr => 2, a nonsignificant rise (4.5 to 6.0 RMMA/h) was noted between 20 and 60 yo. without age effect.
- In the SP sample, the RMMA index < 2 also did not reach significant value; with the RMMA episode/hr =>2, a nonsignificant 35% rise (+1.7 RMMA/h) between 20 and 70 yo. was noted.

Conclusões

Contrary to the decrease of SB self-reports with aging, the PSG-RMMA index remained relatively stable over ages. It remains to be investigated if presence of critical sleep conditions, e.g., insomnia and apnea, influence or bias how patient respond to SB self-report surveys.

Palavras-chave

Sleep Bruxism, Prevalence, rhythmic masticatory muscle activity index (RMMA), Polysomnography