Vibrotactile amplitude and frequency discrimination in temporomandibular disorders

The purpose of this study was to determine whether the elevation in vibrotactile detection threshold, found in many individuals with temporomandibular disorders (TMD), is paralleled by suprathreshold impairments. Participants with TMD were compared with pain-free control subjects in their ability to discriminate on the basis of differences in amplitude and frequency between vibratory stimuli delivered to the face. The TMD group was significantly impaired with respect to frequency discrimination, but not amplitude discrimination. This dissociation suggests that the cortical processing of vibrotactile signals may be affected in TMD patients. TMD participants' estimates of the intensity of their spontaneous and palpation-evoked pain did not significantly correlate with performance on either discrimination task; this finding makes it unlikely that impaired vibrotaction in TMD is primarily the result of a pain-dependent gating of tactile signals.