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Neurological manifestations of intracranial dural arteriovenous malformations
Abstract:
The authors describe their experience with four cases of dural arteriovenous malformation (AVM) which led them to analyze the clinical aspects of these lesions in an attempt to understand their pathophysiology. An additional 191 previously reported cases of dural AVM's were reviewed with special attention to the mechanism of intradural, central, and peripheral nervous system manifestations. Apart from the peripheral cranial nerve symptoms, which are most likely due to arterial steal, the central nervous system (CNS) symptoms appear to be related to passive venous hypertension and/or congestion. Generalized CNS symptoms can be related to cerebrospinal fluid malabsorption due either to increased pressure in the superior sagittal sinus, to venous sinus thrombosis, or to meningeal reaction resulting from minimal subarachnoid hemorrhages. These phenomena are not related to the anatomical type of venous drainage. On the other hand, focal CNS symptoms are specifically indicative of cortical venous drainage. Seizures, transient ischemic attacks, motor weakness, and brain-stem and cerebellar symptoms can be encountered depending on the territory of the draining vein or veins. Therefore, the localizing value of focal CNS symptomatology relates to the venous territory and not to the nidus or to the arterial supply characteristics of dural AVM's. Furthermore, the venous patterns of various dural AVM's at the base of the skull are expressed by differences in their clinical presentation. Dural AVM's of the floor of the anterior cranial fossa and of the tentorium are almost always drained by the cortical veins and, therefore, have a high risk of intradural bleeding. The remarkable similarities in the manifestations of dural and brain AVM's and the differences in the manifestations of dural and spinal dural AMV's are pointed out. High-quality angiograms and a multidisciplinary approach to the study of dural AVM's will provide the best understanding of their symptoms and, therefore, the most appropriate treatment strategy.