Epidemiology and Clinical Course of Chronic Autoimmune Neuropathies During the SARS-CoV-2 Pandemic in Latvia

Background: Chronic autoimmune neuropathies are a group of rare neurological disorders caused by the immune response to autoantigens in the peripheral nervous system. Objective: This study aimed to report epidemiological data in Latvia on the most common chronic autoimmune neuropathies and evaluate SARS-CoV-2 infections or vaccinations’ impact on our patient’s clinical course of the disease. Methods: A single-center observational study was performed, which included all patients diagnosed with chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN) in Latvia since 2015. Prevalence and incidence were calculated by using population data from the corresponding time of the Central Statistics Bureau of Latvia. Detailed clinical evaluation and re-assessment of diagnostic criteria were performed in the whole study group. All patients underwent telephone interviews regarding their SARS-CoV-2 vaccination or infection status. Results: This study included 23 CIDP and 8 MMN patients. The point prevalence and incidence of CIDP were 1.21 per 100 000 people and 1.16 per 100 000 people, respectively. The point prevalence and incidence of MMN were 0.42 per 100 000 individuals and 0.40 per 100 000 individuals, respectively. Most of the patients involved in this study (90%, n=28) with CIDP or MMN were vaccinated against SARS-CoV-2 infection, and none of the patients experienced fluctuations or relapse regarding autoimmune polyneuropathy. Conclusion: The incidence and prevalence of CIDP and MMN in Latvia are similar to previously reported European studies. In our study group, vaccination against SARS-CoV-2 was safe and did not negatively affect the clinical course of CIDP and MMN patients.