The relationship between Ehlers Danlos Syndrome and dysautonomia, the dysfunction of autonomic nervous system, is currently being elucidated. There is a correlation between hypermobility and autonomic symptoms. One study found that in patients with autonomic dysfunction, 18% had EDS, compared to the control group, in which only 4% had EDS.
Ehlers Danlos Syndrome alters collagen structure throughout the body. In HEDS, this usually affects the skin less than in other types of EDS. In the cardiovascular system, this contributes to vascular laxity, which allows excessive dilation of the blood vessels, causing orthostatic intolerance. Importantly, you do not see the spontaneous rupture of blood vessels seen in VEDS.
In HEDS, connective tissue defects in the GI tract lead to dysfunctional peristalsis (contraction of GI tract to move food through it), excessive stretching or swelling, dysregulation of intestinal permeability and damage to the epithelial cells of the GI tract. Without proper connective tissue support, the bladder can become distended or impinge on other structures, as in cystocele. HEDS frequently causes weakness in the pelvic floor and can lead to prolapse of pelvic organs.
Pain and fatigue are often attributed to dysautonomia in EDS patients, but it could also be caused by HEDS. Peripheral neuropathy is prevalent in HEDS and can drive pain in this population. Many HEDS patients have sensory pain, such as tingling, pins and needles, numbness, radiating or burning pain. If the autonomic nervous system is responsible for the pain signals, it could provide a link between dysautonomia and pain. Chronic pain and inflammation can change the structure and behavior of the nervous system, making it easier to transmit pain signals. Orthostatic intolerance can activate the sympathetic nervous system, part of the autonomic nervous system, contributing to these types of symptoms.
By contrast, many HEDS patients are known to frequently have anxiety, palpitations, dizziness, shortness of breath and high affective distress. Rather than being from HEDS directly, these are likely from dysautonomia.
References:
de Wandele I, et al. Dysautonomia and its underlying mechanisms in the hypermobility type of Ehlers-Danlos syndrome. Seminars in Arthritis and Rheumatism 2014, 44: 93-100.
de Wandele I, et al. Autonomic symptom burden in the hypermobility type of Ehlers-Danlos syndrome: A comparative study with two other EDS types, fibromyalgia, and healthy controls. Seminars in Arthritis and Rheumatism 2014, 44: 353-361.
Wallman D, et al. Ehlers-Danlos Syndrome and Postural Tachycardia Syndrome: A relationship study. Journal of Neurological Sciences 2014, 340: 99-102.