Patients with Anti-Sjögren’s Syndrome Type A (Anti-SSA) Have Higher Risk of Neurological Involvement

Patients with Sjögren’s syndrome (pSS), a systemic autoimmune disease that affects the exocrine glands, who have a higher titer of anti-Sjögren’s syndrome type A (anti-SSA) coupled with a low presence of anti-Sjögren’s syndrome type B (anti-SBB) antibodies were shown to have a higher risk of developing neurological involvement, according to a study published in the Journal of Clinical Rheumatology.¹ The disease commonly leads to xerophthalmia and xerostomia as well as conditions such as pneumonitis, renal tubular acidosis, thyroiditis, and myositis.

As pathogenetic mechanisms that are responsible for neurological involvement are unclear and treatment is limited, investigators believe it is important to determine early diagnosis of neurological involvement for patients with pSS. Unfortunately, this is no easy task. Studies such as this are essential for improving the understanding of this disease and allowing researchers to better comprehend indicators of early diagnosis.

The study focused on the prevalence, clinical characteristics, and immunological features of neurological involvement and followed 205 patients (182 women and 23 men) with pSS between January 2015 and June 2017. Diagnosis was based on the 20002 American-European Consensus Group criteria for pSS. Patient characteristics, such as clinical manifestation, weight, assessments of lung, heart, and kidney, as well as disease activity were collected. Additionally, blood and urine examinations, as well as laboratory parameters related to immune features, were included. Patients with pSS and neurological abnormalities were compared with pSS patients without these symptoms. Neurological involvement, a life-threatening complication, is classified into 2 subsets: central nervous system (CNS) and peripheral nervous system (PNS). Patients with CNS had issues with focal or diffuse neurological symptoms, as well as abnormal findings on magnetic resonance images, electroencephalography recordings, and cerebrospinal fluid. Patients with PNS included those with axonal polyneuropathies, sensory ganglioneuronopathy, mononeuritis, trigeminal, and other cranial nerve neuropathies, autonomic neuropathies, and demyelinating polyradiculoneuropathy.

The study found that 19.51% (40/205) patients exhibited abnormalities. Of these, 13 had CNS involvement, 20 had PNS, and 7 had both. Within those affected by neurological involvement, 37 were women and the mean age of onset was 46.43 ± 9.60 years. There were no differences in the occurrence of clinical characteristics between the subset of patients with and without neurological involvement, however disease activity was slightly higher in patients with neurological involvement than those without. Additionally, anti-SSA antibody was significantly higher in patients with neurological involvement and anti-SSB autoantibody was lower.

Investigators found that there was a much higher incidence rate of neurological involvement for patients with pSS than in other studies, which may be due to patient intake coming from the rheumatology department instead of the neurology department, as shown in previous studies. Rheumatologists are more aware of pSS and the prevalence neurological involvement. Additionally, ethnicity may also be a factor in differentiating the results of this study. Investigators also used different study methods and diagnostic criteria for pSS, as well as classifications for neurologic involvement. Other limitations included a limited sample size and possible selection bias.

“The findings from our study support that neurological involvement in patients with pSS is an important issue that needs to be carefully evaluated. It can be difficult to distinguish patients with pSS who are likely to develop neurological abnormities based on pSS-related clinical manifestations and routine blood tests, because they are often similar in patients with and without neurological involvement,” investigators conclude. “Our results indicate that patients with pSS who have a high anti-SSA titer and low presence of anti-SSB antibodies might have a relatively high risk of developing neurological involvement, though this finding still needs to be confirmed in studies with larger cohorts.” Future studies should focus on identifying these biomarkers in order to diagnosis neurological involvement for patients with pSS.

Reference:

Fan G, Dai F, Chen S, et al. Neurological Involvement in Patients With Primary Sjögren's Syndrome. J Clin Rheumatol. 2021;27(2):50-55. doi:10.1097/RHU.0000000000001128