SUDOSCAN® in autoimmune
small fiber neuropathy
Trevino, Jorge A. M.D., Novak, Peter MD. Ph.D.
Article title: TS-HDS and FGFR3 Antibodies in Small Fiber Neuropathy and Dysautonomia.
Muscle Nerve. 2021 Apr 1
JA Trevino and P Novak from Brigham and Women’s Hospital, Harvard Medical School, Boston conducted a study on small fiber neuropathy (SFN) in the idiopathic neuropathy population and investigated the autoimmune etiology of this complication. Autoimmune SFN is a neuropathy where autoimmunity is a causal factor. Immunological abnormalities may underlie up to 19% of patients with idiopathic SFN, according to one study.
Anti-TS-HDS or anti-FGFR3 antibodies have been discovered in patients with idiopathic sensory-predominant SFN, indicating that they could serve as useful markers of neural autoimmunity. Patients with evidence of autonomic dysfunction have TS-HDS/FGFR3 antibodies.
The goal of this retrospective study was to explain the SFN and autonomic profile of patients with anti-TS-HDS and anti-FGFR3.
Small fiber neuropathy was defined as a combination of clinical signs suggestive of small fiber dysfunction and at least one of the following structural or functional variables: abnormal epidermal nerve fiber density (ENFD); abnormal sweat gland nerve fiber density (SGNFD); abnormal sudomotor testing using SUDOSCAN’s measures (the following normative values were used for ESC*/kg: hands ≥1.03μS/kg, feet ≥1.14 μS/kg).
(*) ESC: electrochemical skin conductance
322 patients were included in the study, abnormal ENFD was detected in 71.4%, abnormal ESC/kg (SUDOSCAN) in 63.3%, and abnormal SGNFD in 48.8% of patients.
Frequency of positive or negative Anti-FGFR3 was significantly different among patients with mixed SFN (abnormal ENFD and SGNFD; and combined functional-morphological SFN (Abnormal ENFD, SGNFD, ESC measured with SUDOSCAN)) (see table below).
Only mixed SFN definition segregated seropositive from seronegative patients for anti-FGFR3 but not for anti-TSHDS.
SUDOSCAN measures combined to skin biopsy could be a helpful test to diagnose immune small fiber neuropathy.