[Case with intracranial pial arteriovenous fistulas].

A 25-year-old man presented with right hemiparesis and was admitted to the local hospital. CT scan revealed an intracerebral hematoma in the left motor cortex. He was treated conservatively, the hematoma passed without increase and his right hemiparesis improved gradually. The cause of hemorrhage was examined at the local hospital without resolution. He came to our hospital for further examination. Angiography revealed pial arteriovenous fistulas near the hematoma. The fistulas were fed by small branches of the left anterior cerebral artery and drained into an abnormal cortical vein. Left parietal craniotomy was performed. A red dilated cortical vein existed under the thickened, cloudy arachnoid membrane. Retrograde observation of the red vein showed some small branches connected directly to the red vein at the central sulcus. There was no nidus. The color of the red vein changed to blue after disconnection of the fistulas by electrocoagulation. The dilated cortical vein was resected. Postoperative angiography revealed the disappearance of the fistulas. He was discharged without any new neurological deficits. Intracranial pial arteriovenous fistulas are rare cerebrovascular lesions. As symptomatic patients managed conservatively have a poor prognosis, radical treatment should be undertaken as soon as possible.