[Formation of a posterior fossa cyst after evacuation of chronic subdural hematomas from spinal surgery-induced liquorrhea: a case report]

Cerebrospinal fluid leaks following spinal surgery are relatively common complications. However, subdural hematomas are uncommon, and infratentorial subdural hemorrhages are extremely rare. An 80-year-old man who had a history of myocardial infarction and was being treated with antiplatelet drugs underwent excision of a nerve sheath tumor of the upper cervical spine. Postoperatively, the patient developed headache and experienced weakness in both lower extremities 1 week after the surgery. In addition, he developed vomiting 2 weeks later. Magnetic resonance imaging revealed cerebrospinal fluid retention behind the upper cervical spine, subdural hematomas in the right supra- and infra-tentorial regions, and subdural hygromas in the left supra- and infra-tentorial regions. The chronic subdural hematoma in the right supratentorial region was evacuated through a burr hole. Marked cerebellar ptosis and hydrocephalus developed postoperatively. Thereafter, cerebellar symptoms appeared. The infratentorial subdural hematoma and hygromas diminished in size;however, a posterior fossa cyst was found behind the fourth ventricle. Ten weeks after the burr hole surgery, a ventriculoperitoneal(VP)shunt was installed to decrease the cerebrospinal fluid retention behind the fourth ventricle and to cure the liquorrhea by reducing cerebrospinal fluid flow into the subarachnoid space of the posterior cranial fossa and the spinal canal. The patient's postoperative course was satisfactory, and the liquorrhea disappeared.