Catharina Gross

Autoimmune limbic encephalitis (ALE) presents with new-onset mesial temporal lobe seizures, progressive memory disturbance, and other behavioral and cognitive changes. CD8 T cells are considered to play a key role in those cases where autoantibodies (ABs) target intracellular antigens or no ABs were found. Assessment of such patients presents a clinical challenge, and novel noninvasive imaging biomarkers are urgently needed. Here, we demonstrate that visualization of the translocator protein (TSPO) with [ 18 F]DPA-714-PET-MRI reveals pronounced microglia activation and reactive gliosis in the hippocampus and amygdala of patients suspected with CD8 T cell ALE, which correlates with FLAIR-MRI and EEG alterations. Back-translation into a preclinical mouse model of neuronal antigen-specific CD8 T cell–mediated ALE allowed us to corroborate our preliminary clinical findings. These translational data underline the potential of [ 18 F]DPA-714-PET-MRI as a clinical molecular imaging method for the direct assessment of innate immunity in CD8 T cell–mediated ALE.

Objective The purpose of this study was to characterize patients with ischemic stroke due to bacterial meningitis. Methods In a single‐center retrospective study, we analyzed 102 patients with bacterial meningitis of which 19 had an ischemic stroke. Clinical characteristics, cerebrospinal fluid (CSF) analyses, and spatiotemporal distribution of infarcts were assessed. In addition, we searched PubMed from database inception to August 2021 for observational studies on ischemic stroke in patients with bacterial meningitis, and performed a meta‐analysis to investigate the frequency and timing of stroke as well as its effect on mortality. Results In our cohort, 15 (78.9%) patients with stroke had an modified Rankin scale (mRS) 3 at discharge compared to 33 (39.8%) in patients without stroke ( p < 0.01). Of 1,692 patients with bacterial meningitis from 15 cohort studies included in our meta‐analysis, cerebral infarcts were found in 332 (16%, 95% confidence interval [CI] = 0.13–0.20) patients. The occurrence of stroke was strongly associated with a higher mortality (odds ratio [OR] = 2.38, 95% CI = 1.70–3.34, p < 0.0001). There was no association of any specific causative pathogen with the occurrence of stroke. Infarcts were mainly distributed in territories of arteries located in the vicinity to the infection focus and peaked at 3 to –7 days and at 2 weeks after onset of meningitis. In patients with ischemic stroke, vasculopathy was found in 63.2% and additional intracerebral hemorrhage in 15.8%. Interpretation This study found that ischemic stroke due to bacterial meningitis is caused by cerebral vasculopathy located in the vicinity of the infection focus, and that the time course of infarctions might enable a therapeutic intervention. ANN NEUROL 2023;93:1094–1105