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A 23 year-old woman developed left sided headeaches after a minor care accident. She had pain in the left neck and a Horner's sign on the left.
(Left and Middle) MRI - Axial fat suppression images of the lower brainstem; (right) intracranial MRA. Note the bright signal in the left internal carotid area. The bright signal is blood, indicating a dissection of the carotid artery. On the MRA, note that the artery is narrowed by the dissection. Due to collateral flow at the circle of Willis, dissection do not usually cause strokes by lack of blood flow, but rather from emboli have travel downstream and occlude the MCA, ACA or one of their branches.
The Electronic Curriculum is copyrighted 1998, Case Western Reserve University School of Medicine.