Clinical History: This is a 39-year-old white female with a 15 year history of multiple sclerosis. At diagnosis the patient had weakness and numbness in the lower extremities. Currently, the patient has myoclonus.
Findings: On the axial (Fig.1) proton density (TE 30/TR 2500) and (Fig. 2) and (Fig. 3) T2 weighted images (TE 90/TR 2500) there are rounded areas of increased signal intensity perpendicular to the lateral ventricles. There is a single lesion see on the ( Fig. 4) T1 weighted images (TE 20/TR 750) in the right parieto-occipital region in the periventricular white matter which enhances after the administration of intravenous contrast.
Diagnosis: Multiple Sclerosis
Discussion: Multiple sclerosis is a chronic inflammatory disease of myelin that is of unknown etiology. It has a remitting course and is most commonly seen in female patients with peak age between 20 and 40 years. It is a relapsing-remitting disease which usually presents with weakness and/or numbness in one or more extremities. Another common presentation is visual loss secondary to optic neuritis.
Magnetic resonance imaging is the most sensitive radiographic technique for imaging multiple sclerosis, with sensitivity of nearly 85%. Commonly, foci identified on MRI imaging are clinically silent. A combination of history, physical exam, laboratory tests such as CSF oligoclonal banding and imaging findings are used to diagnose multiple sclerosis.
Multiple sclerosis plaques are typically isointense to hypointense on T1 weighted scans. On proton density and T2 weighted images, the plaques are hyperintense compared to brain. The lesions adjacent to the ependymal surface are best seen on proton density weighted images, contrasted against the lower signal intensity to the CSF within the lateral ventricles.
Multiple sclerosis plaques are commonly seen as round or void discrete lesions in the periventricular white matter. The characteristics Dawson's fingers are the periventricular white matter lesions situated perpendicular to the ventricles as seen in this patient's images. Other common locations for multiple sclerosis plaques include the corpus callosum, corona radiata, internal capsule and centrum semiovale.
Enhancement of M.S. lesions indicate blood brain barrier disruption. This indicates an active demyelinating stage, this is seen in this patient in the right parieto-occipital region. Enhancement can persist up to eight weeks following acute demyelination. Both nodular or ring-like enhancement can be seen after contrast administration. Immediate post contrast scans are most sensitive for detecting active M.S. lesions. Edema and hemorrhage are not characteristics of multiple sclerosis.
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