The pathology of multiple sclerosis (MS) involves both the gray and white matter regions of the brain and spinal cord. It is characterized by various combinations of demyelination, inflammatory infiltration, axonal degeneration, and later
gliosis in chronic lesions. While acute and chronic white matter plaques are well characterized and easily identified,
evidence indicates that the CNS of MS patients may be globally altered, with subtle abnormalities found in grossly
normal appearing white matter (NAWM) and in diffusely abnormal white matter (DAWM) where histochemical stains
and advanced magnetic resonance imaging indicate altered tissue composition. Thus, the prototypical acute
inflammatory lesion may merely represent the most obvious manifestation of a chronic widespread involvement of the
CNS, which is difficult to examine reliably. The current study deals with the microstructure and biochemistry of demyelination, remyelination and axonal loss in various regions of post-mortem human MS brain, including NAWM, areas of remyelination and more typical acute and chronic lesions. The myelin sheath, neuroglia and perivascular spaces were investigated using a novel Coherent Anti-Stokes Raman Scattering (CARS) microscope with simultaneous Two-Photon Excited Fluorescence (TPEF) imaging. The active CH stretching region between ~ 2800 and 3000 cm-1 was probed to provide chemically specific, high resolution, label-free imaging pertaining to the progression of the disease. CARS data were correlated with TPEF and conventional histochemical and immunohistochemical stains.
Our novel CARS microscopy system provides detailed morphological and biochemical information regarding CNS
pathology in MS and that may be applicable to a broad range of other human brain and spinal cord disorders.