Clinical and paraclinical features of small fiber neuropathy in Sjogren's syndrome

Sjogren's syndrome is a potentially treatable cause of Small Fiber Neuropathy (SFN)-a condition that severely affects patients' quality of life. We therefore aimed to characterize patients with SFN and Sjogren's syndrome to raise awareness of this disease and facilitate its early recognition as an essential step for appropriate treatment. In 97 SFN patients (median age 48 years, 77% female), we studied the clinical features associated with Sjogren's syndrome compared to the idiopathic SFN subtype. According to the current ACR/EULAR classification criteria (Shiboski et al., Ann Rheum Dis 76:9-16, 2017), 24/97 individuals (25%, median age 48.5 years, 75% female) were diagnosed with Sjogren's syndrome. We did not observe any differences in SFN-defining sensory plus symptoms. Furthermore, intraepidermal nerve fiber densities (IENFD) were significantly lower in patients with SFN and Sjogren's syndrome (mean 2.6 +/- 1.2/mm) compared to patients with idiopathic SFN (mean 3.2 +/- 1.5/mm; p = 0.048). There were no significant group differences when analyzing cerebrospinal fluid (CSF) parameters. We conclude that Sjogren's syndrome-associated SFN is difficult to distinguish from idiopathic forms based on initial clinical symptoms and CSF results. However, lower IENFD values in patients with Sjogren's syndrome-associated SFN might indicate a distinct different pathomechanism in this entity compared to idiopathic SFN.