Tactile trigeminal region acuity in temporomandibular disorders: A reliability and cross‐sectional study

Abstract

Background Two‐point discrimination (2‐PD) is a valuable test for measuring tactile acuity that provides relevant information about cortical reorganisation and somatosensory function. Objectives The main objectives of the present study were to assess intra‐ and interexaminer reliability of the 2‐PD test in the trigeminal region in asymptomatic individuals and only intra‐examiner reliability in patients with temporomandibular disorders (TMD). The secondary objective was to observe the correlations of the 2‐PD test with regard to pain intensity and psychological and disability variables. Methods Intra‐ and interexaminer reliability of 2‐PD in the trigeminal region was assessed in 40 asymptomatic individuals and 54 patients with TMD. Each clinician received training in the assessment of 2‐PD using an esthesiometer and following a standardised protocol for the three branches of trigeminal nerve. Results In the asymptomatic participants, interexaminer (intra‐class correlation coefficient (ICC .64‐.88) and test‐retest (ICC .70‐.87) values were obtained. Given similar test‐retest values were shown in the group of patients with TMD (ICC .72‐.86), the reliability were considered good‐moderate. Statistically significant differences (P < .001) were obtained between the asymptomatic participants and the patients with TMD regarding the mean values from trials of the three trigeminal branch measurements, with a large effect size. Conclusion Reliability of the 2‐PD test was considered good‐moderate. Patients with TMD showed greater distances in the 2‐PD test, suggesting that tactile acuity in the trigeminal region is impaired in patients with TMD. Assessment of tactile acuity with 2‐PD test in patients with TMD should be considered clinically.

Assessment and Brain Training of Patients Experiencing Head and Facial Pain with a Distortion of Orofacial Somatorepresentation: A Narrative Review

“…For example, in chronic neck [40], low back pain [41] and complex regional pain syndrome [42], activity levels are changed in the somatosensory cortex (S1). In comparison with healthy subjects, TMD patients suffering from myofascial pain have a decreased S1 grey-matter volume as defined by structural MRI, which may be expressed in a reduced sensory function [43], supported by the results obtained at the two-point discrimination test, which indicates a decrease in the discriminative threshold [34]. Tactile acuity depends strictly on the correct functioning of the somatosensory system; thus, the two-point discrimination test has been suggested as a good assessment tool to evaluate S1 area and the somatosensory function [34].…”

“…The cortical disinhibition, together with the central sensitization, present in chronic pain, also drives changes in primary sensory areas and leads to perceptual disturbances [33]. It has been demonstrated that COFP presents with altered epicritic sensibility, due to the presence of reduced tactile acuity [34], altered tactile detection threshold [35] and worse laterality discrimination [36]. Furthermore, proprioceptive and non-proprioceptive alterations, which are manifested through body, perceptual distortions [37] and disturbances of internal and external emotions recognition, have been found in these patients [38,39].…”

Clinical Reasoning for the Examination and Physical Therapy Treatment of Temporomandibular Disorders (TMD): A Narrative Literature Review

“…It is also important to note that the TMD may be associated with body (face) disruption, which can be expressed as alexithymia (a lack of emotional expression and emotional recognition), changes in two-point discrimination, and (facial) motor disturbances [ 105 , 106 , 107 ]. This situation may lead to facial dysmorphic disorders (dysfunctional body image, in this case of the subject’s face) [ 108 ] or prosopagnosia (a severe deficit in recognizing familiar people from their face) [ 109 ].…”

Occlusal tactile acuity in temporomandibular disorder pain patients: A case‐control study

“…However, while animal studies showed that during central sensitisation nociceptive and wide dynamic range neurons develop tactile sensitivity, and animals acquire a facial mechanical hypersensitivity due to a lowered threshold to mechanical stimuli, 30 it is unknown whether this leads to an increased tactile acuity. To add, tactile acuity is decreased in patients with chronic pain including TMD‐pain, 13,31 and delayed‐onset muscle soreness of the masticatory muscles did not affect OTA 22 . Thus, in spite of the animal studies findings, central sensitisation might not be the main mechanism involved in OTA enhancement.…”

“…A recent clinical study demonstrated that tactile acuity in the trigeminal region of patients with temporomandibular disorders (TMD) is impaired 13 . Also, patients with oro‐facial pain complaints frequently report unpleasant sensations associated with somatosensory dysfunction 14 .…”