Regional reduction in cortical blood flow among cognitively impaired adults with relapsing-remitting multiple sclerosis patients

Purpose: Detection of cortical abnormalities in relapsing-remitting multiple sclerosis (RRMS) remains elusive. Structural magnetic resonance imaging (MRI) measures of cortical integrity are limited, although functional techniques such as pseudo-continuous arterial spin labeling (pCASL) show promise as a surrogate marker of disease severity. We sought to determine the utility of pCASL to assess cortical cerebral blood flow (CBF) in RRMS patients with (RRMS-I) and without (RRMS-NI) cognitive impairment. Methods: A total of 19 age-matched healthy controls and 39 RRMS patients were prospectively recruited. Cognition was assessed using the Minimal Assessment of Cognitive Function in Multiple Sclerosis (MACFIMS) battery. Cortical CBF was compared between groups using a mass univariate voxel-based morphometric analysis accounting for demographic and structural variable covariates. Results: Cognitive impairment was present in 51.3% of patients. Significant CBF reduction was present in the RRMS-I compared to other groups in left frontal and right superior frontal cortex. Compared to healthy controls, RRMS-I displayed reduced CBF in the frontal, limbic, parietal and temporal cortex, and putamen/thalamus. RRMS-I demonstrated reduced left superior frontal lobe cortical CBF compared to RRMS-NI. No significant cortical CBF differences were present between healthy controls and RRMS-NI. Conclusion: Significant cortical CBF reduction occurs in RRMS-I compared to healthy controls and RRMS-NI in anatomically significant regions after controlling for structural and demographic differences.