Purpose We describe the spectrum of acute neurological disorders among hospitalized patients who recently had COVID-19 mRNA vaccination. Method We performed a prospective study at 7 acute hospitals in Singapore. Hospitalized patients who were referred for neurological complaints and had COVID-19 mRNA vaccines, BNT162b2 and mRNA-1273, in the last 6 weeks were classified into central nervous system (CNS) syndromes, cerebrovascular disorders, peripheral nervous system (PNS) disorders, autonomic nervous system (ANS) disorders and immunization stress-related responses (ISRR). Results From 30 December 2020 to 20 April 2021, 1,398,074 persons (median age 59 years, 54.5% males) received COVID-19 mRNA vaccine (86.7% BNT162b2, 13.3% mRNA-1273); 915,344(65.5%) completed 2 doses. Four hundred and fifty-seven(0.03%) patients were referred for neurological complaints [median age 67(20–97) years, 281(61.5%) males; 95.8% received BNT162b2 and 4.2% mRNA-1273], classified into 73(16.0%) CNS syndromes, 286(62.6%) cerebrovascular disorders, 59(12.9%) PNS disorders, 0 ANS disorders and 39(8.5%) ISRRs. Eleven of 27 patients with cranial mononeuropathy had Bell's palsy. Of 33 patients with seizures, only 4 were unprovoked and occurred within 2 weeks of vaccination. All strokes occurred among individuals with pre-existing cardiovascular risk factors. We recorded 2 cases of cerebral venous thrombosis; none were vaccine-induced thrombotic thrombocytopenia. Five had mild flares of immune-mediated diseases. Conclusion Our observational study does not establish causality of the described disorders to vaccines. Though limited by the lack of baseline incidence data of several conditions, we observed no obvious signal of serious neurological morbidity associated with mRNA vaccination. The benefits of COVID-19 vaccination outweigh concerns over neurological adverse events.

Objective:To determine whether aquaporin-4 (AQP4) antibody seropositive patients with neuromyelitis optica spectrum disorder (NMOSD) develop new asymptomatic brain lesions during the inter-attack period.Methods:Of 296 consecutive patients with AQP4 antibody seropositive in the NMOSD database of National Cancer Center from May 2005 to November 2019, 145 patients, who had serial brain MRI scans over an interval of at least 1 year during relapse-free period after immunosuppressive therapy, with 370 longitudinally assessed brain MRI scans were included in this study. We retrospectively analyzed them for presence of new subclinical brain lesions during the relapse-free period.Results:Five (3.4%) of 145 patients had detectable new, asymptomatic brain lesions in the deep white matter over a total observed relapse-free period of 708 person-years. All the lesions were less than 6 mm in size and assessed to be non-specific. No brain lesion characteristic of NMOSD or gadolinium-enhancing lesion was identified.Conclusions:Asymptomatic brain lesions are rarely observed on conventional MRI in clinically stable AQP4 antibody seropositive patients with NMOSD after immunosuppressive therapy and brain MRI lesions characteristic of NMOSD are not seen in the relapse-free period. These findings may provide further insight regarding currently known diagnostic and disease monitoring strategies in NMOSD.