[Learning disorders after ruptured aneurysms of the anterior communicating artery]

Abstract

The aim of this study was to reevaluate short term and long term memory disorders after anterior communicating artery rupture, then to more specifically assess the importance and the role of forgetting, proactive and retroactive interferences, impaired memory for temporal order, attention disorders and dysexecutive syndrome, and finally MRI-defined brain lesions. Twenty one patients presenting with selective anterior brain injury, were assessed at the secondary and late post stroke phases. The short term memory analysis showed the digit span was reduced at the secondary stage, but that mean performances were preserved in the Peterson and Sternberg paradigms. Verbal and visuospatial learning in long term memory showed a severe deficit in free recall, chiefly serial, and associative recall. Recognition was mildly impaired at the secondary phase, and later normalized. A definite and lasting increase of proactive and retroactive interferences and an impairment in discriminating the temporal order of word presentations were observed. Amnesic impairment was relatively well correlated with forgetting, severity of interferences and temporal order amnesia, so as with disorders of attention and executive functions (Wisconsin Card Sorting Test). However, intrusions in free recall and false recognitions were not clearly related with the dysexecutive syndrome. The severity of amnesia was associated with lesions of the left anterior cingulate cortex, and of the corpus callosum. These results suggest that these patients mainly had a deficit in information retrieval, mostly compromising long term memory, but also to a lesser degree short term memory. Forgetting, interferences and the dysexecutive syndrome probably play an important role in the decline of mnemonic performance, but do not clearly explain intrusions in recall and errors in recognition.