Patterns of pain variation related to myogenous temporomandibular disorders

Myogenous temporomandibular disorders are characterized by jaw muscle pain. The aims were: 1) to characterize this pain generally in terms of intensity, frequency, duration, and behavior across a period of 2 weeks; 2) to identify main intraday pain patterns and to examine whether subgroups of patients in this respect differed in clinical, demographic, pain and sleep variables, psychosocial factors, and use of medication; and 3) to investigate some possible interday trends of pain intensity at a group level.

One hundred thirty-three patients with myogenous temporomandibular disorders completed a 2-week diary, rating pain intensity (100 mm Visual Analog Scale [VAS]), duration, behavior (verbal 6-point scale), and medication use on 4 times of the day. Furthermore, questionnaires were completed to score pain period before seeking treatment, spread of pain, and demographic, psychosocial, and sleep variables.

In the diary, pain intensity, frequency, daily pain duration, and the score of pain behavior were on average 29.1 mm, 69% of the scoring times, 5.5 hours, and 1.8 points (approaching "pain present, but I can ignore it at times"), respectively. Pain intensity was, on average, maximal late in the day (before dinner or bedtime) for the majority of patients (79%) and early in the day (before breakfast or lunchtime) for the minority (21%). The larger subgroup had a significantly higher daily pain intensity, more frequently a widespread pain and problems with falling asleep at bedtime, agreed more about the role of a physician as an external health locus of control, and had a more distancing coping style. Both subgroups were similar for other variables, most notably in the level of state anxiety and depressive mood, and in a sparse use (7.8% of all possible times) of over-the-counter medication. Daily mean VAS scores, averaged across patients, were approximately constant for the various diary days. Both the daily mean and maximal VAS score were not related to a specific day of the week.

Two main daily pain patterns occur in patients with myogenous temporomandibular disorders (79%: maximal pain late in the day; 21%: early in the day), which might be related to differences in processes that influence pain sensitivity and patterns of jaw muscle activation. The interday similarities in pain level suggest that a sustained influence of counseling after the intake or an influence of a common behavioral pattern with a cycle duration of a week are not involved.