You might think that having floppy joints would be a bonus. Yoga would certainly be a lot easier. You would be able to touch your toes better than the rest of the class and as far as standing on your shoulders and bending your legs back over your head, it would be as easy as falling off a log. But there’s the thing. It is the muscles, tendons and ligaments that protect joints from damage. If there is any weakness in those, it would lead to instability, injury and arthritis.
I first learnt about Ehlers-Danlos Syndrome (EDS) when I was a medical student at The London Hospital 50 years ago. It was an oddity, a condition that allowed contortionists and escapologists to earn a living. Described as a rare inherited disorder of connective tissue by Doctors Edvard Ehlers and Henri-Alexandre Danlos 100 years ago, EDS is characterised by varying degrees of tissue fragility, skin hypo-elasticity and joint hypermobility. We had no idea then of more serious implications apart from somewhat fragile, inelastic skin, which held its shape when you pinched it (cutis laxa) and delayed wound healing. In recent years, however, Ehlers Danlos has come out of the circus tent into the consulting room, affecting joints, skin, blood vessels, nerves, the heart and the gut. No fewer than six different subtypes have been identified. The hypermobile type is the most common with hyperextensible (bendy) joints, often complicated by muscle weakness, arthritis and a lot of pain. But hypermobile EDS (hEDS) is associated with symptoms as variable as palpitations, dizziness, headaches, chronic pain, bladder frequency, anxiety and mood disorders, pelvic organ prolapse and a surprisingly high prevalence of gut symptoms.
In the latest issue of Gut Reaction, my colleague, Professor Qasim Aziz, head of The Wingate Institute at The London Hospital, reported that in an unselected group of more than 500 patients referred to his gastroenterology clinic, 180 (33%) had hEDS. ‘These patients reported a higher frequency of heartburn, fullness after meals, bowel habit alternating between constipation and diarrhoea, bloating and difficulty with swallowing than non-hypermobile patients. Furthermore, the prevalence of hEDS in IBS patients was approximately 40% and in patients with functional dyspepsia (unexplained indigestion, early fullness and discomfort after meals) was 50%. In 2013, another study from the USA showed that of 134 hEDS patients, 48% met criteria for IBS.’ Further research carried out at The Wingate Institute has demonstrated disturbances in motility throughout the gut in EDS, especially obstructed defaecation and difficulty in swallowing.
Hypermobile EDS is also more common in a range of other poorly explained illnesses, including fibromyalgia, chronic fatigue syndrome, migraine, and tempero-mandibular joint dysfunction (clicking jaws). And, like all of those conditions, it is more common in women than men.
But how could a skeletal condition, an inherited disorder of connective tissue, affect your guts? Well fibrous tissue (collagen) forms the skeleton of the gut and holds it together, providing a structure for muscles and elastic tissue to work against. Deficiencies in collagen could therefore lead to a floppy gut with stasis and complications such as delayed gastric emptying, small intestinal bacterial overgrowth and constipation. But, while joint hypermobility is more common in IBS-constipation, it is also found in IBS diarrhoea. Moreover, IBS is an illness that tends to come and go, which doesn’t quite fit with a genetically determined structural defect, unless we acknowledge the possibility that hEDS encompasses a spectrum of collagen deficiency, which may be affected by a range of environmental factors.
How would we explain reports that that explain that visceral sensitivity is increased in hEDS? Might deficiencies in microscopic support for capillaries irritate the gut neurones by causing extravasation of blood? Might lack of collagenous support for enteric neurones result in increased sensitivity? Might there be some interference with cell adhesion causing a leaky gut and invasion by bacteria? The possibilities are legion, but as far as I am aware, there is no evidence for any of these.
People with joint hypermobility suffer increased anxiety and depression. They are also in more pain and may be incapacitated by debilitating complications such as clicking or locked jaw, severe headaches (which might be caused by muscular tension related to an unstable cervical spine), collapsed foot arches, an unstable gait and arthritis. It would be surprising if the burden of pain, disability and instability did not make them upset from time to time. Many try to ignore their disability and plough on regardless, but as ever, the body keeps the score and the extra tension and exhaustion may be expressed as a sensitive gut, fibromyalgia and chronic fatigue.
Association doesn’t necessarily imply cause and effect. The more factors that are associated with IBS, the more it suggests multiple routes to the same illness and/or a resetting of gut sensitivity caused by the interaction of a variety of factors.
It would be wonderful if the association between joint hypermobility and IBS had led to the development of novel treatments. It hasn’t …. yet, but the team at The Wingate Institute is currently conducting detailed physiological studies to determine the cause of the gastrointestinal symptoms in people with EDS. This work is important because early detection of EDS in people with symptoms of IBS could eliminate complications caused by unnecessary surgical and drug intervention and hopefully lead to development of new and more specific treatments for IBS.