A 13-year-old boy presented to the emergency department after sudden onset of right-sided hemiparesis and slurred speech. The patient developed acute weakness on the right side of his body and face while walking back to his bed after using the restroomin the early m orning hours. He had no pain, numbness, or visual disturbance. The day before presentation the patient fell while rollerskating but denied any injury resulting fromthe event. Examination showed a right-sided central facial paresis, right-sided pure motor hemiplegia, and a right Babinski sign. The patient had dysarthric speech but showed no aphasia. The remainder of the neurologic examination yielded normal results. Diffusion-weighted magnetic resonance imaging (MRI) of the brain showed an area of restricted diffusion in the left hippocampus, globus pallidus, and posterior limb of the internal capsule (Fig 1). Magnetic resonance angiography (MRA) showed narrowing of the left common carotid artery extending into the left internal carotid and intracranially to the origin of the left anterior choroidal artery (Figs 2 and 3). Enlarged T1 cervical MR images confirmed decreased flow in the left internal carotid and a ring of increased signal within its lumen consistent with arterial dissection (Fig 4).