Background: This study explored whether Myelin Water imaging could detect myelin injury in Anti-NMDA receptor autoimmune encephalitis (NMDAr-AIE), where traditional neuroimaging is often normal. Myelin Water Fraction (MWF) quantifies myelin content by distinguishing myelin sheath water from other brain water compartments. Methods: Adult participants with confirmed NMDAr-AIE diagnoses and healthy controls (HC) underwent 3T brain MRI including MWF mapping. Participants were recruited after discharge from the hospital. Mean MWF was calculated for 4 white matter regions of interest (ROI). Patient demographics, clinical assessments, treatment, and outcomes were collected. Results: Five participants with NMDAr-AIE (4F/1M, mean age 30, SD 7) and four HC (3F/1M, mean age 36, SD 6) were included. All NMDAr-AIE participants had normal or non-specific T2 hyperintensities on initial imaging and had received immunotherapy. The mean Modified Rankin Score (MRS) on discharge was 2. MWF (mean ± SD) for normal-appearing white matter, corpus callosum, corticospinal tract, and superior longitudinal fasciculus were 0.10±0.02, 0.12±0.02, 0.15±0.03, 0.12±0.02, which were very similar to HC at 0.09±0.02, 0.11±0.01, 0.15±0.02, and 0.11±0.02, respectively. Conclusions: Myelin Water imaging showed no myelin pathology in five NMDAr-AIE patients, with MWF values comparable to HC. This suggests that myelin pathways are relatively preserved post-recovery from AIE.

Background: Susac Syndrome (SuS) is a rare autoimmune disorder of the cerebral, retinal, and inner ear microvasculature. One of the cardinal manifestations of central nervous system (CNS) involvement is encephalopathy, however the cognitive profile in SuS is poorly characterized in the literature. Methods: In this cross-sectional case series of seven participants diagnosed with Susac Syndrome in remission in British Columbia, we use a battery of neuropsychological testing, subjective disease scores, and objective markers of disease severity to characterize the affected cognitive domains and determine if any disease characteristics predict neuropsychological performance. We also compare this battery of tests to neuroimaging markers to determine if correlation exists between radiographic markers of CNS disease and clinical evaluation of disease severity. Results: There were a variety of cognitive deficits, with memory and language dysfunction being the most common. Despite the variability, performance on some neuropsychological tests (MoCA) correlated to markers of functional disability (EDSS). Additionally, MoCA and EDSS scores correlated with neuroimaging findings of both corpus callosum and white matter changes. Finally, psychiatric scores correlated with participant reported scores of disease severity. Conclusions: There is a relationship between cognitive deficits, subjective and objective disease disability, and neuroimaging findings in Susac Syndrome.