Parsonage-Turner Syndrome following COVID-19 Vaccination: A Systematic Review.

Background: Parsonage-Turner syndrome (PTS) is an inflammatory condition of the brachial plexus, with more than half of patients presenting a trigger, such as infection or vaccination. Our objective was to synthesize the clinical and paraclinical features, therapeutic responses, and outcomes of PTS post-COVID-19 vaccination.

Methods: We systematically reviewed two databases (LitCOVID and the WHO database on COVID-19) up to January 2024 following a published protocol (OSF registries).

Results: We included 59 cases. PTS occurred more frequently in males (61.1% mRNA group, 83.3% viral vector group). Patients in the mRNA group were younger (41.7% between 41 and 50 years vs. 38.9% between 61 and 70 years). Most cases had sudden pain within two weeks. Unilateral PTS was present in 94.4% of mRNA and all viral vector-vaccinated cases. Symptoms included pain (97.1% and 92.3%, respectively), usually followed within two weeks by motor deficits (97.2% and 94.1%, respectively), amyotrophy (30% and 81.8%, respectively), paresthesia (50% and 27.3%, respectively), and sensory loss (33.3% and 38.5%, respectively). Viral vector vaccine recipients had nerve involvement outside the brachial plexus. Ancillary investigations revealed CSF albuminocytological dissociation (33.3% and 100%, respectively) and ipsilateral axillary lymphadenopathy. Two PTS cases worsened after the second mRNA dose, and another recurred after influenza vaccination. One patient well tolerated the second dose of the viral vector vaccine, but symptoms reemerged in another.

Conclusions: Current evidence suggests PTS may occur after all COVID-19 vaccine types, with some subgroup differences. Also, PTS might recur with subsequent similar or unrelated vaccines.