Skin biopsy reveals generalized small fibre neuropathy in hypermobile Ehlers–Danlos syndromes

Background and purpose Ehlers–Danlos syndromes are hereditary disorders of connective tissue that are characterized by joint hypermobility, skin hyperextensibility and tissue fragility. The most common subtype is the hypermobile type. In addition to symptoms of small fibre neuropathy (SFN) due to damage to the small peripheral nerve fibres, with degeneration of the distal nerve endings, autonomic disorders such as postural tachycardia syndrome (PoTS) are frequently reported features in patients with hypermobile Ehlers–Danlos syndrome (hEDS). To date, the underlying pathophysiological mechanisms are still not completely understood. Study Purpose To better understand pathophysiological mechanisms of small fiber neuropathy and autonomic neuropathy in hypermobile Ehlers‐Danlos Syndromes. Methods We prospectively investigated 31 patients with hEDS compared to 31 healthy controls by using skin biopsy, quantitative sensory testing, tilt‐table testing, the painDetect, Small Fibre Neuropathy Screening List and the COMPASS‐31 (Composite Autonomic Symptom Score 31) questionnaire. Results Nineteen (61%) patients with hEDS were diagnosed with SFN, and 10 (32%) fulfilled the criteria for PoTS. Patients with hEDS had significantly higher heart rates than controls. According to quantitative sensory testing, these patients had generalized thermal and tactile hypesthesia. Skin biopsy revealed significantly reduced intraepithelial nerve fibre density proximally (thigh) and distally (lower leg) in patients compared to controls. This was consistent with various complaints of pain and sensory disturbances in both the proximal and distal body regions. Conclusion These results confirm histologically proven SFN as a common feature in patients with hEDS, revealing a generalized distribution of nerve fibre loss. Regarding the frequently reported autonomic and neuropathic dysfunctions, the findings support SFN as an important, but not the only, underlying pathomechanism.