Abstract
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.
Cook MK, Jordan M. Autoimmune Small Fiber Neuropathy Associated With Ehlers-Danlos Syndrome Treated With Intravenous Immunoglobulins. J Clin Neuromuscul Dis. 2021 Mar 1;22(3):160-163. doi: 10.1097/CND.0000000000000341. PMID: 33596000.
Abstract
Patients with Ehlers-Danlos syndrome (EDS) have many associated symptoms of unclear cause, most recently suggested to be due to small fiber neuropathy (SFN). Small fiber neuropathies are sorely underestimated and with minimal treatment options. We report 2 cases of patients with EDS with presumed immune-mediated SFN, successfully treated with IV immunoglobulins. There is a stark need for further investigational studies into immunosuppressant treatments for immune-mediated SFN as well as the link between EDS and immune-mediated SFN.
Ghasemi M, Rajabally YA. Small fiber neuropathy in unexpected clinical settings: a review. Muscle Nerve. 2020 Aug;62(2):167-175. doi: 10.1002/mus.26808. Epub 2020 Feb 4. PMID: 31943276.
Abstract
Small fiber neuropathy (SFN) is being recognized with increasing frequency in neuromuscular practice due to improved diagnostic techniques. Although there are some common etiologies, up to one-third of cases are considered idiopathic. In recent years, several disorders have unexpectedly been reported in association with SFN, on clinical grounds and complementary investigations, including quantitative sensory testing, intraepidermal nerve fiber density and confocal corneal microscopy. Knowledge of these disorders is important in clinical practice as increased awareness enables prompt diagnosis of SFN in these settings and early optimal therapeutic management of affected patients. Furthermore, these new developments may lead to a better understanding of the pathophysiologic mechanisms underlying SFN in these different disorders as well as, in some cases, an expanded spectrum of affected organs and systems. This article reviews these reported associations, their possible pathophysiologic bases, and the potential resulting management implications.
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