Qualitative and Quantitative Aspects of Pain in Patients With Myotonic Dystrophy Type 2

Abstract

Pain is a common but often ignored symptom in patients with myotonic dystrophy type 2 (DM2). In this explorative study, we assessed qualitative and quantitative aspects of pain in DM2 using 4 questionnaires and quantitative sensory testing. A disease control group (fibromyalgia [FMS]) as well as healthy controls were used to compare the results, because pain in DM2 shows many clinical similarities to pain in FMS. Thirty-four patients with genetically confirmed DM2 (71% female, mean age 54 years), 28 patients with FMS, and 33 healthy controls were included, age- as well as sex-matched. Pain prevalence was 65% in DM2, 100% in FMS (P < .001), and 15% in healthy controls (P < .001). The mean of the pressure pain thresholds was lower in DM2 than in healthy controls (P = .016), with the largest differences in the rectus femoris, trapezius, and thenar muscles. Mechanical and electric pain thresholds were significantly higher in DM2 than in FMS, and no differences were found in electric pain thresholds between DM2 and healthy controls. These results confirm that pain is a frequent and important symptom in patients with DM2, affecting quality of life. Peripheral mechanisms of pain seem to play a role in DM2. The widespreadness of the hyperalgesia suggests central sensitization, but this finding was not supported by the other results. This study opens new avenues for further research and eventually novel treatment strategies, in DM2 as well as in other muscular disorders.

Perspective: This article presents qualitative as well as quantitative aspects of pain in patients with DM2. Pain is a frequent and important symptom in patients with DM2, affecting quality of life. We found mechanical hyperalgesia, indicative of a peripheral mechanism of pain. The widespreadness of hyperalgesia may suggest central sensitization, but this finding was not supported by other results and needs further exploration.

Keywords: Myotonic dystrophy type 2; central sensitization; fibromyalgia syndrome; pain; quantitative sensory testing.