Researchers at Johns Hopkins Children's Center report that children and teens with chronic fatigue syndrome are three-and-a-half times more likely to have hyperflexible joints than their healthy counterparts.
The findings, reported in the September issue of The Journal of Pediatrics, contradict widely shared clinical observations that people with CFS have normal physical examinations. CFS is an often disabling constellation of fatigue- and pain-related symptoms that can interfere with daily life and cause long absences from school.
"This study suggests either that hypermobility itself is an important factor in the development of CFS, or it is associated with another factor that predisposes a person to CFS," says lead researcher Peter C. Rowe, a professor of pediatrics at the Children's Center.
Rowe cautions that joint hypermobility alone is not a direct cause of CFS. "We know that about 20 percent of healthy adolescents have joint hypermobility, but clearly most do not go on to develop CFS, so simply finding this on an exam need not start a search for CFS," Rowe says.
Researchers examined 116 children, ages 10 and older, for joint hypermobility. The test group was split evenly between patients diagnosed with CFS and otherwise healthy children. Joint hypermobility was graded on the degree to which a patient could bend the pinkie finger back beyond 90 degrees; bend the thumb to touch the forearm; hyperextend the knee beyond 190 degrees; hyperextend the elbow beyond 190 degrees; and place the palms flat on the floor without bending the legs. Sixty percent of those with CFS showed joint hypermobility, compared with 24 percent of the healthy children.
The link between flexible joints and CFS may provide further insight into the development of CFS symptoms because an individual's degree of joint mobility is apparent in early childhood, long before the onset of CFS symptoms, Rowe says.
Children with CFS often have orthostatic intolerance, a condition associated with excessive pooling of blood that results in heart and blood pressure problems, headaches, dizziness and other symptoms. Rowe and colleagues had previously reported that patients with orthostatic intolerance also have Ehlers-Danlos syndrome, a connective tissue disorder characterized by joint hypermobility.
Researchers from the departments of Pediatrics and Dermatology and the McKusick-Nathans Institute of Genetic Medicine contributed to the study.