A 32-year-old man with stuporous mental state was transferred to our hospital emergency room after a car accident. The brain computed tomography(CT) showed 4th ventricular hemorrhage. He woke up 2 weeks after admission and then discharged. However, he returned to the hospital 10 months after discharge because of both shoulder pain and weakness of both arms. His brain CT showed marked dilatation of the 4th ventricle. His MRI showed whole spinal syringomyelia without Chiari malformation. The patient then underwent ventriculo-peritoneal shunt. His symptoms dramatically improved on the immediate postoperative day, and the syringomyelia also disappeared after operation. The authors report a very rare case of syringomyelia that was developed as a sequelae, especially of the 4th ventricular dilatation without intracranial pressure elevation after traumatic hydrocephalus and cerebellar atrophy, favoring Gardner's hypothesis.