[Mixed pial-dural arteriovenous malformation. Case report].

The authors report a case of mixed pial-dural arteriovenous malformation (mixed pial-dural AVM), which had feeders from both cortical branches of the internal carotid artery and middle meningeal artery of the external carotid artery. A clinical course of this case is presented and literatures are reviewed. Moreover the authors stress the rete mirabile anastomoses as an important factor in the genesis of the mixed pial-dural AVM. The patient, 30-year-old female, suddenly suffered from a severe headache on December 31, followed by gradual deterioration of consciousness. She was admitted to Otaru Second City Hospital one hour after the episode and neurological examination disclosed moderate confusion, right hemiparesis and neck stiffness. CT scan revealed a massive hematoma in the bilateral ventricles and left parietal lobe and skull plain film showed an enlargement of the groove of the middle meningeal artery. Angiography revealed a mixed pial-dural AVM in the left parietal lobe, which had feeders from both cortical branches of the left internal carotid artery and middle meningeal artery of the left external carotid artery. Two weeks later the admission, an operation was performed. A ligation of the external carotid artery at the neck was performed before a craniotomy, and the bleeding from the dura was minimal, and the AVM in the parietal lobe was removed completely. The patient recovered satisfactorily without any trouble and she was discharged with only a mild weakness at the right side. The clinical finding of the mixed pial-dural AVM is discussed and the rete mirabile anastomoses is emphasized as an important factor in the genesis of the mixed pial-dural AVM.