Meningeal inflammation is a progressively recognized finding in multiple sclerosis (MS). The real prevalence of leptomeningeal enhancement (LME) in different stages of MS and its association with neurodegeneration is still a matter of debate.
To assess the in-vivo prevalence of LME in relapsing-remitting MS (RRMS) and to evaluate the association with clinical/radiological activity and cerebrospinal fluid (CSF) markers.
This is an ongoing observational study. LME was assessed by two blinded neurologists on a 3D 1x1x1 mm3 Fluid-Attenuated-Inversion-Recovery (FLAIR) acquired 20 minutes post gadolinium (TR 6000 ms; TE 356 ms; Fat suppressed). LME was defined as signal intensity within the subarachnoid space greater than that of brain parenchyma and brighter on postcontrast scans. MRI activity was defined as at least 1 gadolinium enhancing and/or new/enlarging T2 lesions. Differences in terms of clinical, radiological, CSF metrics between patients with and without LME were tested with ANOVA, chi square and binary logistic regression analysis as appropriate.
38 RRMS patients were included in the analysis: [65,2% female, mean age 37,8±10.1 years mean disease duration 10,1±9.2 years, median Expanded-Disability-Status-Scale (EDSS) 2 (0-6,5)]. 78,3% of patients had MRI activity in the previous 2 years: among them 17,4% had uniquely radiological activity and 60,9% had clinical relapses (experiencing disease progression in 17,4 % of cases), 26.1% had ongoing MRI activity. LME was found in 37% of patients, median number 1 (range 1-3). No difference in EDSS, age and disease duration was found between patients with or without nodules. LME prevalence was higher in patients with previous MRI activity (P=0.047). Multivariable models adjusted for baseline EDSS exploring predictive value of clinical progression, previous MRI activity, ongoing MRI activity show that previous MRI activity was the only variable associated with LME (p=0.002). CSF parameters had no predictive value for LME development nor any association was found between presence of oligoclonal bands and LME.
LME was found in a discrete proportion of RRMS patients and it was associated with previous, but not ongoing, radiological activity. A prospective clinical evaluation is needed in order to assess the prognostic value of our findings.