[P3-161] A 9-year-old boy developed perimesencephalic nonaneurysmal subarachnoid hemorrhage in playing catch
Perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSH) is a benign type of subarachnoid hemorrhages (SAH). Though PNSH is a distinct type of SAH in adults, it is extremely rare and not well recognized in the pediatric population. We describe another pediatric case of PNSH. A 9-year-old, previously healthy boy was admitted to our hospital because of sudden onset of headache, vomiting and disturbance of consciousness. These symptoms developed when he was playing catch. Head injury was not present. Head computed tomography on admission showed high density areas in the pontocerebellar cistern and the ambient cistern. Cerebral angiography revealed no abnormal findings. Bilateral basal veins of Rosenthal drained mainly into the vein of Galen. We diagnosed the illness as PNSH on the basis of these radiological findings. We did conservative and symptomatic therapy and the patient quickly recovered without any neurological sequelae. In adult, it is reported that more than 50% of PNSH developed in or after physical exertion, which leads to the increased intracranial venous pressure. The present case shows that exercise may be a trigger of PNSH in children just as in adult patients.