There are periventricular plaques of greyish demyelination in white matter characteristic for multiple sclerosis (MS). Women are affected twice as often as men. There are oligoclonal bands of immunoglobulin detectable in the CSF of over 90% of patients with MS. These bands are the result of B cell proliferation, which suggests an autoimmune etiology for MS. Increased myelin basic protein may also be detected in the CSF. There is a genetic linkage of MS to the DR2 haplotype of the HLA complex. The plaques can develop in white matter anywhere in brain and spinal cord and appear at irregular intervals, resulting in the waxing and waning course of illness. Myelin is lost. Myelin is the 'insulation' around axons, similar to the insulation on electrical wires, and its loss results in 'short circuits' that cause a host of neurologic problems, particularly optic neuritis.