Pterional Transsylvian Research Articles

Combined infratemporal epidural and medial triangle approachによる脳底動脈先端部動脈瘤の手術

Surgical techniques for a combined infratemporal epidural and medial triangle approach to basilar tip aneurysms consists of 1) an orbitozygomatic frontotemporal craniotomy, 2) an infratemporal epidural approach in order to expose the nerve sheathes of the IInd and Ist divisions of the trigeminal nerve and the medial half of the gasserian ganglion, 3) a pterional transsylvian approach for opening the superior wall of the cavernous sinus via the medial triangle and 4) unveiling the cavernous sinus medial to the IInd division of the trigeminal nerve.Seventeen cases of ruptured basilar tip aneurysms which were operated on via this orbitozygomatic infratemporal transcavernous approach were divided into three groups and the clinical features were reviewed. The fact that out of 4 cases in the early-operation group only one case showed good operative result seems to be attributed to the serious original Hunt and Kosnik Grade of the patients. All 3 cases with Hunt and Kosnik Grades I and II in the relatively early-stage operation group (operated on between Day 6 and Day 10) were good postoperatively. The operative result of 6 out of 8 cases with Grade I or II in the delayed-operation group was good. Conclusion: 1. This transcavernous approach seems to be the preferable approach to the basilar tip aneurysm in the early stage, with several advantages such as 1) wide exposure of the operative field, 2) the shortest possible distance with only slight retraction of the temporal tip with its dura mater, and 3) no division of the Sylvian vein and the spheno-parietal sinus running within the temporal dura propria. 2. Clipping of the basilar tip aneurysm being located either in higher or lower position can be performed successfully without retracting the carotid artery and its tributaries.

側頭葉内側部～大脳基底核部脳動静脈奇形の全摘術

Arteriovenous malformations (AVMs) in the basal ganglia region have been a problem in neurosurgical practice. Because of their location, hemorrhage from deep-seated AVMs may result in severe neurological deficits and mortality. But the surgical management of deep-seated or large AVMs has been complicated and is fraught with considerable risk. We report a successfully excised case of AVM in the medial temporal lobe~basal ganglia.A 24-year-old man was admitted to our clinic complaining of severe headache and left upper quadrant anopsia after a third subarachnoid hemorrhage. Their plain CT scan on admission demonstrated diffuse subarachnoid hemorrhage, right infratemporal hematoma and clots in the right lateral ventricle. Cerebral angiograms showed an arteriovenous malformation (AVM) in the right medial temporal lobe~basal ganglia. The feeding arteries were the anterior temporal polar artery and the lenticulostriate arteries. The draining vein was the basal vein of Rosenthal. This AVM was classified Grade IV according to Spetzler and Martin's classification systems. 123 I-IMP SPECT demonstrated a low perfusion area in the whole right hemisphere. Enhanced CT scan showed a frontoparietal enhanced lesion within the low perfusion area. From these findings it was assumed that the risk of normal perfusion pressure breakthrough syndrome was very high. Because of these pathophysiological conditions, we decided to do a multi-staged operation.First operation: Via a pterional transsylvian approach, the feeding arteries were dissected. The anterior temporal polar artery and two main lenticulostriate arteries were clipped. At this point the local cortical blood flow at the precentral gyrus was markedly elevated from 32ml to 74ml/100g/min. 0.3ml of ethyl-cyanoacrylate was injected into the nidus from the distal end of the anterior temporal polar artery.Second operation: Two weeks after the first operation, microsurgical total excision was performed. First the hematoma cavity was approached through a cortical incision at the insula. The nidus was relatively well demarcated from the cavity and gliotic plane of the temporal lobe and basal ganglia. The AVM was totally removed without temporary occlusion of the anterior choroidal artery nor the many perforating arteries.After total exision of the AVM, left hemiparesis developed but later recovered to an almost normal level.In conclusion, the staged approach to deep-seated or large AVM's is proposed as a method to render totally excisable, AVM's that were previously considered inoperable. We show the feasibility of satisfactory microsurgical treatment of these lesions based on a knowledge of microanatomical studies and pathophysiology of AVMs.