Differences in clinical features between small fiber and sensitive large fiber neuropathies in Sjögren's syndrome

Anti-Plexin-D1 Seropositive Small Fiber Neuropathy: Clinical Phenotype, Demographics, and Literature Review

OBJECTIVES

Small fiber neuropathy (SFN) is a subtype of painful neuropathies defined by dysfunction of the Aδ and unmyelinated C fibers. It presents with both neuropathic pain and dysautonomia symptoms, posing a significant diagnostic and therapeutic challenge. To address this challenge, research has been conducted to identify autoantibodies and define their association with phenotypes.

METHODS

Eleven cases of anti-plexin-D1 seropositive SFN were reviewed, along with relevant literature, in attempt to better define anti-plexin-D1 SFN demographics, symptoms, associated medical conditions, and therapeutics.

RESULTS

Anti-plexin-D1 SFN typically presents in female patients, with neuropathic pain, normal skin biopsy findings, and normal nerve conduction studies. Anti-plexin-D1 shows an association with concurrent chronic pain, with almost half of the patients undergoing an interventional procedure.

CONCLUSIONS

Anti-plexin-D1 represents a unique subgroup of SFN, defined by distinct demographics, phenotype, biopsy findings, and therapeutic management.

Primary Sjögren syndrome-related peripheral neuropathy: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Primary Sjögren syndrome (pSS) is a chronic, systemic, autoimmune disorder characterized by lymphocytic infiltrates of the exocrine organs, leading to sicca symptoms and parotid enlargement. pSS has been linked to various neurological manifestations, including peripheral neuropathy (PN). We aimed to provide a comprehensive analysis of the currently available evidence regarding pSS-related PN.

METHODS

A literature search in the PubMed database was performed, and 49 papers were eligible to be included in this systematic review and meta-analysis.

RESULTS

The pooled prevalence of PN in pSS is estimated to be 15.0% (95% confidence interval = 10.7%-20.7%). The mean age of pSS patients at PN diagnosis is 59 years. Among the patients with pSS and PN, 83% are females. Neuropathic symptoms usually precede or lead to the pSS diagnosis at a 2:1 ratio in patients with pSS-related PN. The commonest type of pSS-related PN is distal axonal polyneuropathy (80% of patients with pSS-related PN), followed by sensory ganglionopathy. Peripheral and cranial mononeuropathies-particularly trigeminal-are also frequent. Risk factors for developing PN include increasing age and presence of vasculitis. Immune-mediated pathogenetic mechanisms are discussed. Glucocorticoids are the most commonly used treatment option for managing pSS-related PN, when associated with vasculitis, followed by the use of intravenous immunoglobulin.

CONCLUSIONS

PN is very common in pSS patients. Evidence on long-term prognosis of PN in pSS is limited, and further research is needed. Research into the use of immunosuppressive medication in nonvasculitic neuropathies in the context of pSS merits further consideration.

Discordant Predictions of Extraglandular Involvement in Primary Sjögren's Syndrome According to the Anti-SSA/Ro60 Antibodies Detection Assay in a Cohort Study

Electrophoresis-derived techniques for anti-SSA/Ro60 KDa (anti-SSA) antibodies detection have been progressively replaced by methods using non-native antigens. We aimed to compare the patients’ phenotypes and the occurrence of extraglandular manifestations in primary Sjögren’s syndrome according to the method used to detect anti-SSA antibodies. Sera from patients with a diagnosis of pSS according to ACR/EULAR 2016 criteria between 2008 and 2017 were tested for anti-SSA antibodies using methods with non-native antigens (magnetic bead multiplex assay; line immunoassays) and one with native antigens (counterimmunoelectrophoresis (CIE)). The population was split into three groups according to anti-SSA antibodies status: absence (SSA−), presence in any method except for CIE (SSA+CIE−), and presence in CIE (SSA+CIE+). The patients in the SSA+CIE+ group (n = 70, 42.7%) were ten years younger and presented more immunological activity compared with both the SSA− (n = 80, 48.8%) and SSA+CIE− groups (n = 14, 8.5%). The SSA− and SSA+CIE− groups were poorly distinct. The presence of anti-SSA antibodies solely in CIE was significantly associated with the occurrence of extraglandular manifestations of pSS (HR = 4.45 (2.35–8.42)). Contrary to CIE, methods using non-native antigens to detect anti-SSA antibodies were unable to predict the occurrence of systemic expression of pSS.

Non-length-dependent small fiber neuropathy: Not a matter of stockings and gloves

The clinical spectrum of small fiber neuropathy (SFN) encompasses manifestations related to the involvement of thinly myelinated A-delta and unmyelinated C fibers, including not only the classical distal phenotype, but also a non-length-dependent (NLD) presentation that can be patchy, asymmetrical, upper limb-predominant, or diffuse. This narrative review is focused on NLD-SFN. The diagnosis of NLD-SFN can be problematic, due to its varied and often atypical presentation, and diagnostic criteria developed for distal SFN are not suitable for NLD-SFN. The topographic pattern of NLD-SFN is likely related to ganglionopathy restricted to the small neurons of dorsal root ganglia. It is often associated with systemic diseases, but about half the time is idiopathic. In comparison with distal SFN, immune-mediated diseases are more common than dysmetabolic conditions. Treatment is usually based on the management of neuropathic pain. Disease-modifying therapy, including immunotherapy, may be effective in patients with identified causes. Future research on NLD-SFN is expected to further clarify the interconnected aspects of phenotypic characterization, diagnostic criteria, and pathophysiology.

Association of Primary Sjögren's Syndrome and Vitamin B12 Deficiency: A Cross-Sectional Case-Control Study

Descriptive and retrospective studies without control groups have suggested a possible association between primary Sjögren's syndrome (pSS) and vitamin B12 (B12) deficiency. This is of importance because several mucosal and neurological features are common to these two conditions and could be prevented or reversed in case of B12 deficiency. We aimed to evaluate the association between pSS and B12 deficiency. We prospectively assessed the B12 status of 490 patients hospitalized in an internal medicine department over a 15-week period. Patients with pernicious anemia were excluded. We extracted patients with pSS and paired them with controls according to age and sex, with a 1:5 ratio. Twenty-one pSS patients were paired with 105 control patients. The median age was 70 years old (51-75) and 95.2% of patients were women. The plasma B12 level was lower in pSS patients (329 (293-521) ng/L vs. 456 (341-587) ng/L, p < 0.0001). B12 deficiency was associated with pSS (42.9% among pSS patients vs. 11.4% among controls), even after adjustment for other causes of B12 deficiency (OR 6.45 (95%CI: 2.08-20.0)). In conclusion, pSS appeared to be associated with B12 deficiency, even after the exclusion of pernicious anemia. This justifies screening and treating B12 deficiency in pSS patients.