Dawson fingers on MRI are best described as periventricular, ovoid demyelinating lesions oriented perpendicular to the lateral ventricles. These findings are characteristic of which disease?

• A. Multiple Sclerosis
• B. Alzheimer's disease
• C. Amyotrophic lateral sclerosis
• D. Migraine

Answer: (A)

Dawson fingers reflect periventricular demyelinating plaques caused by multiple sclerosis. In MS, immune-mediated attack on CNS myelin creates lesions that track along the ventricles, giving ovoid foci that extend perpendicularly away from the ventricular surface—hence the perpendicular, finger-like appearance on MRI. On T2-weighted or FLAIR images these lesions appear bright near the ventricles and are a classic imaging hallmark of MS.

The other conditions don’t produce this characteristic pattern. Alzheimer’s disease centers on cortical and hippocampal atrophy rather than periventricular demyelinating plaques. Amyotrophic lateral sclerosis can involve the corticospinal tracts but doesn’t typically show Dawson fingers. Migraine isn’t associated with this specific periventricular, perpendicular-to-ventricle lesion layout.