Unfolding the long-term pathophysiological processes following an acute inflammatory demyelinating lesion of multiple sclerosis

Abstract

Acute symptomatic inflammation is a main feature of multiple sclerosis but pathophysiological processes underlying total or partial recovery are poorly understood. To characterize in vivo these processes at molecular, structural and functional levels using multimodal MR methods. A neuroimaging 3-year follow-up (Weeks 0, 3, 11, 29, 59 and 169) was conducted on a 41-year-old woman presenting at baseline with a large acute demyelinating lesion of multiple sclerosis. Conventional magnetic resonance imaging (MRI), magnetization transfer imaging, diffusion-weighted imaging, functional MRI and magnetic resonance spectroscopy were conducted at 1.5 T. Patient presenting with subacute left hemiplegia recovered progressively (expended disability status scale 7 to 5.5). The MR exploration demonstrated structural functional and metabolic impairments at baseline. Despite restoration of the blood brain barrier integrity, high lactate levels persisted for several weeks concomitant with glial activation. Slow and progressive structural and metabolic restorations occurred from baseline to W169 (lesion volume -64%; apparent diffusion coefficient -14.7%, magnetization transfer ratio +14%, choline -51%, lipids -78%, N-acetylaspartate +77%) while functionality of the motor system recovered. Multimodal MRI/MRS evidenced long-term dynamics recovery processes involving tissue repair, glial activation, recovery of neuronal function and functional systems. This may impact on customized rehabilitation strategies generally focused on the first months following the onset of symptoms.