Dawson's fingers

Dawson's Fingers

Dawson's fingers are a radiological feature seen on magnetic resonance imaging (MRI) of the brain, typically associated with multiple sclerosis (MS). These lesions are named after the Scottish pathologist James Walker Dawson, who first described them in 1916. Dawson's fingers are characterized by their perpendicular orientation to the lateral ventricles, resembling fingers extending from the corpus callosum.

Pathophysiology

Dawson's fingers are a result of demyelination, which is the loss of the myelin sheath insulating the nerves. In multiple sclerosis, the immune system mistakenly attacks the central nervous system, leading to the formation of plaques or lesions. These lesions are often found around the small veins in the brain, particularly in the periventricular region, which is why they appear as "fingers" radiating from the ventricles on MRI.

Imaging Characteristics

On MRI, Dawson's fingers are best visualized using T2-weighted and FLAIR (Fluid Attenuated Inversion Recovery) sequences. They appear as hyperintense (bright) areas on these sequences. The characteristic appearance of Dawson's fingers helps in the diagnosis of multiple sclerosis, as they are indicative of the perivenular distribution of demyelinating lesions.

Clinical Significance

The presence of Dawson's fingers on MRI is a strong indicator of multiple sclerosis, although they are not exclusive to the disease. Their identification can aid in the differentiation of MS from other neurological conditions that may present with similar symptoms but have different radiological features.

History

James Walker Dawson first described these lesions in his 1916 paper, "The Histology of Disseminated Sclerosis," where he detailed the pathological findings in the brains of patients with multiple sclerosis. His observations laid the groundwork for understanding the radiological appearance of MS lesions.

Also see

• Multiple sclerosis
• Demyelination
• Magnetic resonance imaging
• James Walker Dawson