Fascial thickness and stiffness in hypermobile Ehlers-Danlos syndrome.

There is a high prevalence of myofascial pain in people with hypermobile Ehlers-Danlos Syndrome (hEDS). The fascial origin of pain may correspond to changes in the extracellular matrix. The objective of this study was to investigate structural changes in fascia in hEDS. A series of 65 patients were examined prospectively-26 with hEDS, and 39 subjects with chronic neck, knee, or back pain without hEDS. The deep fascia of the sternocleidomastoid, iliotibial tract, and iliac fascia were examined with B-mode ultrasound and strain elastography, and the thicknesses were measured. Stiffness (strain index) was measured semi-quantitatively using elastography comparing fascia to muscle. Differences between groups were compared using one-way analysis of variance. hEDS subjects had a higher mean thickness in the deep fascia of the sternocleidomastoid compared with non-hEDS subjects. There was no significant difference in thickness of the iliac fascia and iliotibial tract between groups. Non-hEDS subjects with pain had a higher strain index (more softening of the fascia with relative stiffening of the muscle) compared with hEDS subjects and non-hEDS subjects without back or knee pain. In myofascial pain, softening of the fascia may occur from increase in extracellular matrix content and relative increase in stiffness of the muscle; this change is not as pronounced in hEDS.