Sensory characteristics and chronic facial pain conditions: Cross-sectional study

Abstract

Objectives: This study investigated patients with neuropathic, myofascial and other orofacial pain conditions according to the differences and similarities of the sensory profile, and the association between sensory findings and neuropathic or non-neuropathic conditions.

Design: 132 healthy controls were compared with 174 orofacial pain patients that were classified into three groups (neuropathic, masticatory myofascial and other orofacial pain condition) and evaluated with a systematized protocol of sensory testing. Data were analyzed with chi-quare and Bonferroni correction (categorical data), Student´s t test, oneway ANOVA, Tukey (quantitative features), Pearson´s coefficient for correlations and logistic regression.

Results: Cold, olfactory and superficial pain thresholds were higher in the group of neuropathic facial pain compared with the other groups, and the highest vibratory thresholds were observed in the group of other orofacial pain conditions. Deep pain thresholds were statistically lower in the group with masticatory myofascial pain.

Conclusions: Positive sensory findings (eg. hyperalgesia) were more common in the group of patients with masticatory myofascial pain, supporting inflammatory systemic mechanisms, and negative sensory findings not restricted to the trigeminal nerve (eg. hypoesthesia, hyposmia) were more frequent in patients with neuropathic conditions. Non-classical neuropathic orofacial pains also showed sensory impairment from pain chronification and from the overlap with functional disorders.

Keywords: Chronic pain; Orofacial pain; Regression; Sensory characteristics.