Increased somatosensory amplification is associated with decreased pressure pain thresholds at both trigeminal and extra-trigeminal locations in healthy individuals.

Abstract

The diagnosis of temporomandibular disorders (TMD) is based on patient history and physical examination, and may require medical imaging. Masticatory muscle palpation is essential to make a diagnosis of TMD. However, the response of masticatory muscles to mechanical pressure stimuli depends on many physical and psychological factors. This study aimed at determining the impact of somatosensory amplification (SSA)-an estimate of somatic awareness and bodily hypervigilance-on pressure pain thresholds (PPTs) measured at both trigeminal and extra-trigeminal locations in healthy individuals. PPTs were measured at the right anterior temporalis and superficial masseter, and the thenar eminence of the right hand in one hundred healhty individuals (69F, 31M), divided in three groups based on their SSA scores: low (N=32), intermediate (N=34) and high (N=34). General linear models were used to test between-group differences in PPTs including sex as a covariate. The level of significance was set at P<.05. Individuals with high SSA had lower PPTs at the anterior temporalis than individuals with low (P=.006) and intermediate (P=.001) SSA. No significant between-group differences were found in PPTs measured at the masseter (P=.372). PPTs measured at the thenar eminence were significantly lower in the high than the low SSA group (P=.009). Females had lower PPTs at the masseter than males (P=.021) but not at other muscle locations (all P>.05). Increased somatosensory amplification is associated with decreased pressure pain thresholds at both trigeminal and extra-trigeminal locations in healthy individuals. SSA could be a potential confounder while diagnosing TMD and evaluating treatment outcomes.