OCLN and secondary progressive multiple sclerosis: The pathological findings using autopsy brain section from patients with SPMS or relapsing MS demonstrated that the highest level of BBB disruption including a lack of ZO-1 and occludin was observed in active lesions (affecting 40% of vessels), although it was more apparent in inactive lesions (23%) and normal-appearing white matter (NAWM) (13%) than in neurological (8%) and normal (4%) controls [12], [13].