[A case of hematoma in cisterna magna after mild head injury].

An 18-year-old man suffered severe neck pain, signs of meningeal irritation, and dysesthesia of his left breast and left arm after mild head injury incurred in a traffic accident. On the next day, magnetic resonance imaging(MRI) revealed a hematoma in the cisterna magna, and it extended into the posterior spinal subdural space. Eight days after admission, MRI demonstrated the hematoma on the right posterior aspect of the spinal cord at the level of craniovertebral junction. These MRI findings suggested a ruptured bridging dorsal vein from the spinal cord to the occipital or marginal sinus. The usefulness of MRI for diagnosis of localized hematoma around the craniovertebral junction and the mechanism of this hemorrhage are discussed.