Applied Radiology

Diagnosis

Multiple Sclerosis

Findings

Multiple foci of white matter signal abnormality are identified involving the left centrum semiovale as well as the subcortical white matter of the right temporal lobe. Small foci of signal abnormality are identified bilaterally, medially within the cerebellar peduncles. There is abnormal enhancement, without enlargement, of the right optic nerve.

Discussion

Multiple sclerosis is a disease process characterized by the formation of demyelination plaques within the white matter of the brain and spinal cord. There is a 60:40 female predominance, with most cases occurring between the ages of 18 and 50. There are a number of theories regarding the causation of multiple sclerosis. Some of these include post-traumatic, post-viral and genetic susceptibility resulting in immune mediated white matter disease. The course of multiple sclerosis is typically relapsing and remitting. In rare cases, also known as Marburg type multiple sclerosis, the disease is rapidly progressive and debilitating. Visual problems and eye pain are frequent presenting symptoms due to optic neuritis. MRI is the best imaging study to evaluate for multiple sclerosis with a sensitivity of 85%. Abnormal periventricular foci of signal abnormality are identified with enhancement seen in active plaques. Three such lesions measuring greater than 5mm each is suggestive of the diagnosis. Lesions that appear ovoid, located at the callosal-septal interface are known as "Dawson's Fingers", and are also suggestive.

Orrison Jr, William. Neuroimaging. W.B. Saunders Company, Philadelphia, 2000