Neuropsychological deficits as predictors of treatment outcome in patients with temporomandibular disorders

The primary objective of this study was to assess the utility of neuropsychological tests as predictors of treatment outcome for patients with temporomandibular disorders (TMD). Psychosocial and clinical variables were also included as confounders and secondary outcome measures. In the overall, the nrTMD did worse in both the neuropsychological and psychosocial assessment with higher memory deficits, sleep disturbances, levels of depression and fatigue, and lower energy levels; but both groups could not be distinguished from each other based on clinical variables usually assessed in the TMD examination. The California Verbal Learning Test - correct responses (CVLTCR), the California Verbal Learning Test - clusters (CVLTCL), and the Brown-Peterson Consonant Trigram Auditory Memory Task (CCC) were capable of differentiating responding (rTMD) versus non-responding TMD (nrTMD) patients prior to treatment even after controlling for eleven psychosocial and clinical variables used in the analysis and other four included in the design. Among the best predictors, the CCC in a backward stepwise logistic regression was chosen as the best predictor of all neuropsychological tests. Three psychosocial variables were also found to be good predictors: (a) sleep, (b) depression, (c) fatigue, and (d) income. Among clinical variables, only pain on chewing pre-treatment was found to be predictors. Our secondary objective was to assess if the neuropsychological and psychosocial profile between irritable bowel syndrome (IBS) and nrTMD patients were much more similar than those between the IBS and the rTMD group. On average, both nrTMD and IBS patients did worse in the neuropsychological and psychosocial tests than the rTMD with higher memory deficits, higher levels of depression, sleep disorders and fatigue, and lower energy levels. Taken in combination, the data suggested that neuropsychological differences exist between the nrTMD versus rTMD patients. In addition, it was also demonstrated that two unrelated chronic pain conditions (i.e. IBS and nrTMD) may share similar neuropsychological characteristics. Therefore, solid and reproducible evidence was provided with the use of neuropsychological tests in favor of the biopsychosocial model of chronic pain. This study also supported the multidisciplinary management approach for patients with temporomandibular disorders.