Right hemisphere stroke. Magnetic resonance imaging (MRI) scan of an axial section of the brain of a 49-year-old female patient after a cerebrovascular accident (CVA), or stroke. The stroke has occurred in the right hemisphere (left) of the brain, which can lead to muscle weakness or paralysis on the left hand side of the patient's body. This patient's stroke is likely to have been caused by the presence of an internal carotid artery dissection (ICAD) in the right hemisphere. ICAD is an uncommon cause of stroke that typically occurs after head trauma, but can also occur spontaneously. Strokes are caused by the blood (and oxygen) supply to the brain being cut off, and can be instantly fatal, or may pass unnoticed. This is a T2-weighted MRI scan.