Small fiber neuropathy following SARSCOV- 19 vaccination. A case series

ABSTRACT

Background and aims: Small fiber neuropathy (SFN) is a polymorphous disease affecting thin nervous fibers conducting temperature and pain sensations and involved in autonomic transmission. Etiology is diverse and remains elusive in 70% of cases. Methods: We describe a case series of 6 patients who developed symptoms of SFN following SARS-COV-19 vaccination. Neurologic examination was normal whilst paraclinical results were consistent with SFN. Confirmation by skin biopsy was obtained in 4 cases. Results: Six patients, 5 female and 1 male, ages 31, 34, 39, 42, 44 and 62 years, consulted our department with intense pain and numbness involving the arms and legs 2 to 15 days following SARS-COV-19 vaccination. Neurologic examination was normal. A preliminary diagnostic protocol comprising autoimmune, metabolic, infectious and inflammatory panel, cerebral and spinal cord magnetic resonance imaging and electromyography was normal. Functional neurophysiologic testing showed reduced activation of fibers involved in sweat gland control indicating SFN. Skin biopsy of distal calf and thigh in 4 patients, three female and one male, showed rarefaction of thin intraepidermic nerve fibers in a non length dependent manner, allowing for a diagnosis of SFN. Conclusion: Whereas autoimmune, infectious, metabolic, toxic and genetic causes are well described in SFN, evidence of possible association with vaccination is confounding. Given their small caliber and richness of surface antigens, small nervous fibers are vulnerable to a wide spectrum of disease. Immunologic factors intervening on a predisposing substrate could be a hypothesis for the mechanism involved in development of SFN following SARS-COV-19 and possibly other vaccination.