Background Fibromyalgia (FM) is related to the features of small fiber neuropathy (SFN). Sudoscan is a non-invasive device measures sweat gland dysfunction employing electrochemical skin conductance (ESC) and is useful for assessing peripheral small fiber nerve function. Little is known about the dysfunction of peripheral small fiber nerve in patients with FM.
Objectives The aim of this study was to evaluate the prevalence and characteristics of SFN in patients with FM compared with a control group and to identify factors associated with SFN in FM.
Methods 66 patients with FM (age: 53 ± 9 years old) to meet 2010 ACR preliminary diagnostic criteria and 66 healthy controls were enrolled. Each FM patient was required to fast 8 to 10 hours before blood samples. Serum fasting glucose, fasting insulin, Serum 25-(OH) D and the 75-gram two-hour oral Glucose tolerance test (GTT) were measured. Height and weight were measured and used to calculate Body mass index (BMI). Overt diabetes patients were excluded using their past and medication history. The small fiber neuropathy Symptoms Inventory Questionnaire (SFN-SIQ) was used to record neuropathic symptoms. Clinical assessments included fibromyalgia impact questionnaire (FIQ), Beck Depression Inventory (BDI), and The State-Trait Anxiety Inventory (STAI). All subjects underwent the examination of Sudoscan.
Results The mean feet and hands ESC were significantly lower in the FM group than the control group.(table 1).
Mean Hands ESC was irrelevant to age, BMI, SFN-SIQ, FIQ, fasting glucose, fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and vitamin D and 2 hour GTT glucose level. However, Mean feet ESC showed significant correlation with fasting insulin (r= -0.34, p<0.01) and HOMA-IR (r= -0.37, p<0.01).
Conclusions Sudomotor function was significantly lower in patients with FM than the control group. Mean feet ESC was correlated with hyperinsulinemia and HOMR-IR in patients with FM, which implies that SFN associated with insulin resistance may play an important role in FM pain.
Neurophysiol Clin. 2015 Dec;45(6):445–55. Epub 2015 Nov 17. Diagnosis of small fiber neuropathy: A comparative study of five neurophysiological tests.
Curr Pain Headache Rep. 2015 Dec;19(12):55. The Role and Importance of Small Fiber Neuropathy in Fibromyalgia Pain. Caro XJ, Winter EF
Disclosure of Interest None declared
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