The McGill Pain Questionnaire in patients with TMJ pain and with facial pain as a somatoform disorder.

The purpose of this study was to assess the discriminative capacity of the McGill Pain Questionnaire (MPQ) in patients with temporomandibular joint disorders (TMD) or with facial pain disorder as somatoform disorder (referred to as "atypical facial pain") (FP). The MPQ was administered to 57 TMD and 34 FP patients. Weighted MPQ item scores, subscale Pain Rating Indexes (PRI), and total Pain Rating Index were tested for significant differences (Student's t-test), and the frequency of descriptor choice was also analyzed. Furthermore, the data were processed through two systems based on a counter-propagation neural network: the Self-Organizing Map (SOM) system and a cluster-like analysis. In the FP group eleven MPQ item scores and five PRI scores were significantly higher than those of the TMJ group. There was a considerable difference in descriptor choice between the groups. SOM analysis and cluster-like analysis correctly discriminated 85% or more of the patients. In conclusion, the MPQ showed a consistent discriminative capacity between TMD and FP patients.