Somatosensory abnormalities in Chinese patients with painful temporomandibular disorders

Guangju Yang, Lene Baad-Hansen, Kelun Wang, Kaiyuan Fu, Qiu-Fei Xie, Peter Svensson

The somatosensory phenotype of Chinese temporomandibular disorders (TMD) patients is not sufficiently studied with the use of contemporary techniques and guidelines. A standardized quantitative sensory testing (QST) battery consisting of 13 parameters with a stringent statistical protocol developed by the German Research Network on Neuropathic Pain was performed over the most painful and corresponding contralateral sites as well as the right hand of 40 Chinese patients with TMD and pain classified according to the Diagnostic Criteria for TMD (DC/TMD). The same QST protocol was performed bilaterally over the infraorbital, mental, and hand regions of 70 age- and gender-stratified healthy Chinese controls. Z-scores and loss/gain scores were computed for each TMD patient. For patients, 82.5 % had somatosensory abnormalities in the painful facial region, while 60.0 % had abnormalities confined to the right hand. The most frequent abnormalities were somatosensory gain to pinprick (35.0 %) and pressure (35.0 %) stimuli, somatosensory loss to pinprick (25.0 %), cold (22.5 %), and heat (15.0 %) nociceptive stimuli. The most frequent loss/gain score was L0G2 (no somatosensory loss combined with a gain of mechanical somatosensory function) for both the facial (40.0 %) and hand (27.5 %) regions. Involving side-to-side differences in the evaluation increased the diagnostic sensitivity by 2.5-25.0 % across different parameters. Somatosensory abnormalities were commonly detected in Chinese TMD pain patients both within and outside the primary painful region, strongly indicating disturbances in the central processing of somatosensory stimuli. The individual variations in somatosensory abnormalities indicate a possible need for development of individualized TMD pain management.