Clinical Presentation:
Multiple sclerosis is a disease that gradually destroys myelin and oligodendrocytes, the cells that produce myelin. This destruction of the myelin sheath slows the transmission of nerve impulses. The cause of this disease is unknown. This disease is most common with women (60%) between the ages of 20 and 40, especially those with a Northern European heritage. Common symptoms associated with multiple sclerosis are optic neuritis (acute inflammation of the optic nerve), numbness, dysesthesia, and burning sensations in the arm, leg, and face. Some experience Lhermitte's signs, which are electric, shooting pains down the back, arms, and legs when the neck if flexed.
Pathology:
Most multiple sclerosis patients have ovoid periventricular lesions along the callospetal interface and the corpus callosum and spinal cord. Acute MS plaques have a pink color with a soft consistency, but as the plaques age, they become firmer, translucent, and gelatinous.
Image Findings:
CT shows hypodense plaques and generalized atrophy. Active lesions with ring-like enhancement. MR images show ovoid-shaped lesions located in the periventricular white matter of the corpus callosum, visual pathways, and brain stem. Lesions may also involve gray matter since myelinated fibers travel through gray matter. These lesions are hypointense on T1WI, hyperintense on T2WI and slightly hyperintense on PDWI. Blood-brain barrier breakdown in "active" or inflammatory lesions cause slight enhancement.
Differential diagnosis:   
Differential diagnosis includes metastases, small vessels infarcts or vasculitis.