Effects of intra-articular ketamine on pain and somatosensory function in temporomandibular joint arthralgia patients.

Author(s): Ayesh EE, Jensen TS, Svensson P

Affiliation(s): Department of Clinical Oral Physiology, School of Dentistry, University of Aarhus, Vennelyst Boulevard 9, DK-8000 Aarhus, Denmark.

Publication date & source: 2008-07-15, Pain., 137(2):286-94. Epub 2007 Oct 17.

Publication type: Randomized Controlled Trial; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Recent studies have hypothesized that peripheral glutamate receptors could be implicated in deep craniofacial pain conditions. In this study 18 temporomandibular joint (TMJ) arthralgia patients received intra-articular injections of the N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine, or normal saline to study in a cross-over, double-blinded, placebo-controlled manner the effect on TMJ pain and somatosensory function. Spontaneous pain and pain on jaw function was scored by patients on 0-10 cm visual analogue scale (VAS) for up to 24h. Quantitative sensory tests (QST): tactile, pin-prick, pressure pain threshold and pressure pain tolerance were used for assessment of somatosensory function at baseline and up to 15 min after injections. There were no significant effects of intra-articular ketamine over time on spontaneous VAS pain measures (ANOVA: P=0.532), pain on jaw opening (ANOVA: P=0.384), or any of the somatosensory measures (ANOVA: P>0.188). The poor effect of ketamine could be due to involvement of non-NMDA receptors in the pain mechanism and/or ongoing pain and central sensitization independent of peripheral nociceptive input. In conclusion, there appears to be no rationale to use intra-articular ketamine injections in TMJ arthralgia patients, and peripheral NMDA receptors may play a minor role in the pathophysiology of this disorder.