Acute Asymmetric Sensorimotor Variant of Chronic Inflammatory Demyelinating Polyneuropathy Triggered by mRNA-1273 COVID-19 Vaccination.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) developing in the postvaccination period was distinctly unusual and its course was rarely well described. We aimed to clearly depict the clinical features of acute-onset multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) caused by mRNA-1273 COVID-19 vaccination. A 74-year-old man noticed weakness of hands 2-3 days after he accepted the second dose of mRNA-1273 COVID-19 vaccine. He soon became unable to walk within one week. Initially, muscle power of bilateral hand grasping was most severely affected. He had stayed on at the nadir for 3.5 months until the diagnosis of CIDP was made. Nerve conduction studies showed typical evidences of acquired demyelinating, but no sural spare pattern. He was treated with intermittent pulse steroid therapy. Two weeks after treatment, INCAT disability score improved from 10 to 4, but remained at 4 thereafter: arm disability score was 3 and that of leg was 1, which suggested muscles of upper limbs were more severely affected. Diagnosis of acute-onset MADSAM was challenging at the beginning of this disease. For vaccine-triggered CIDP, time to symptom onset could be as short as 2-3 days. Delay in recognition may influence the remission of this disease. Muscles of upper limbs were more affected than those of lower limbs. Intermittent steroid pulse therapy would be an alternative to daily oral steroid therapy. Keyword: chronic inflammatory demyelinating polyradiculoneuropathy, COVID-19 vaccination.