A 15-year-old boy suddenly experienced acute right-sided headache and dizziness followed by drowsy consciousness and left-sided weakness after practicing backward somersaults. Nonenhanced CT image of the brain (a) showed increased attenuation at the M1 segment of the right MCA (white arrowhead). Apparent diffusion map of the brain (b) delineated a 2.4-cm low-signal area in the posterior limb of the right internal capsule, consistent with a hyperacute infarct (arrow). Magnetic resonance angiography of the brain (c) showed focal stenosis of the right MCA with decreased flow and number of distal branches (white arrowhead).
