Trigeminal pain and quantitative sensory testing in painful peripheral diabetic neuropathy

To evaluate patients with Diabetes Mellitus type 2 and painful peripheral neuropathy in order to investigate oral complaints and facial somatosensory findings.

Case-control study; 29 patients (12 women, mean age 57.86 yo) with Diabetes Mellitus type 2 and 31 age-gender-matched controls were evaluated with a standardized protocol for general characteristics, orofacial pain, research diagnostic criteria for temporomandibular disorders, visual analogue scale and McGill Pain questionnaire, and a systematic protocol of quantitative sensory testing for bilateral facial sensitivity at the areas innervated by the trigeminal branches, which included the thermal detection by ThermoSensi 2, tactile evaluation with vonFrey filaments, and superficial pain thresholds with a superficial algometer (Micromar). Statistical analysis was performed with Wilcoxon, chi-square, confidence intervals and Spearman (p<0.05).

Orofacial pain was reported by 55.2% of patients, and the most common descriptor was fatigue (50%); 17.2% had burning mouth. Myofascial temporomandibular disorders were diagnosed in 9 (31%) patients. The study group showed higher sensory thresholds of pain at the right maxillary branch (p=0.017) but sensorial differences were not associated with pain (p=0.608). Glycemia and HbA(1c) were positively correlated with the quantitative sensory testing results of pain (p<0.05) and cold (p=0.044) perceptions. Higher pain thresholds were correlated with higher glycemia and glycated hemoglobin (p=0.027 and p=0.026).

There was a high prevalence of orofacial pain and burning mouth was the most common complaint. The association of loss of pain sensation and higher glycemia and glycated hemoglobin can be of clinical use for the follow-up of DM complications.