Neuropsychological Effects of Brain Arteriovenous Malformations

Abstract

Brain arteriovenous malformations (AVM’s) are a complex tangle of abnormal veins and arteries that are missing a capillary bed.  They are thought to begin during fetal development, undergo an unclear maturation process, and most often do not become symptomatic until adulthood. Prospective studies have suggested that relatively few patients present with neuropsychological abnormalities in the absence of hemorrhage. In general, neuropsychological evaluations of patients with AVM have yielded mixed results with respect to localization of function, and most cognitive studies have not been able to demonstrate the nature and degree of impairment seen in acute ischemic stroke in comparable brain regions. Superselective Wada testing prior to therapeutic embolization, functional imaging studies and intrasurgical cortical mapping have shown redistribution of language and memory, often to distant regions that my represent functional networks. Developmental cognitive history in these patients indicates that most will have at least some background of learning problems during the school-age years with varying degrees of severity, indicating a time when brain reorganization may be occurring. These data suggest that traditional assumptions about eloquence of brain regions may not hold for patients with AVMs, and that establishing treatment risk in the individual patient needs to be made on an empirical basis.