The Clinical Features of Painful Small‐Fiber Neuropathy Suggesting an Origin Linked to Primary Sjögren's Syndrome

Objective We attempted to determine whether clinical features could differentiate painful small‐fiber neuropathy related to primary Sj€ogren's syndrome ( pSS ‐ SFN ) from idiopathic SFN (idio‐ SFN ). Methods Validated clinical questionnaires and neurophysiological investigations specific for pain and SFN assessment were performed in 25 patients with pSS ‐ SFN and 25 patients with idio‐ SFN . Results Patients with idio‐ SFN had more frequent severe burning sensations and higher mean anxiety scores and daily pain intensity compared to patients with pSSSFN . Conversely, patients with pSS ‐ SFN had reduced electrochemical skin conductance measured by Sudoscan_, and almost half of them had the sensation of walking on cotton wool. Conclusion Our results suggest that idio‐ SFN more specifically involved small sensory fibers than pSS ‐ SFN , in which subtle dysfunction of larger sensory fibers and damage of distal autonomic sudomotor innervation may occur. A practical algorithm is proposed to help to differentiate SFN associated with pSS from idio‐ SFN , based on information very easy to obtain by clinical interview.