Inflammatory Sixth Nerve Palsy Post-COVID-19 Vaccination: Magnetic Resonance Imaging Findings

Sixth nerve palsy is the most common post-vaccination oculomotor palsy. It is generally transient with most patients making a complete recovery. We report the case of a 46-year-old healthy male patient who presented with a painless sixth nerve palsy after the second dose of the Pfizer BioNTech COVID-19 vaccine, which recovered over the course of the next month. We confirmed the lesion localisation by demonstrating enhancement of the root exit zone and the cisternal portion of the sixth nerve on sequential magnetic resonance imaging during the symptomatic period. Here, a temporal relationship between vaccine application and diplopia onset suggests an aetiologic relationship. Moreover, the lack of pre-existing medical conditions suggests a post-vaccination inflammatory process.