Multifocal motor neuropathy after SARS-CoV-2 vaccination: a causal or coincidental association?

Multifocal motor neuropathy (MMN) is an immune-mediated and acquired demyelinating motor polyneuropathy. Several cases of polyneuropathy associated with severe acquired respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination have been reported. However, MMN has not been reported as a complication of SARS-CoV-2 vaccination. In this study, we report a case of MMN with progressive muscle weakness following the second dose of the Pfizer-BioNTech mRNA vaccine. It was diagnosed by clinical evaluation and electroneuromyography. SARS-CoV-2 vaccination is increasing rapidly all over the world. Some cases of polyneuropathy, especially Guillain–Barré syndrome, have been reported after vaccination. This is the first case report of MMN after SARS-CoV-2 vaccination.