PRESERVATION OF PROCEDURAL MEMORY IN 18 P ATIENTS AFTER SURGERY OF ANEURYSMS OF THE ANTERIOR COMMUNICATING ARTERY

Organic amnesia is typically associated with lesions in either the die ncephalic or medial temporal regions of the brain. However, amnesia ca n result from other kinds of lesions, in particular those resulting fr om an aneurysm of the anterior communicating artery (ACoA). In the pre sent study, 7 patients who became amnesic following a ruptured and ope rated ACoA aneurysm were comparated neuropsychologically with 11 patie nts with ruptures but no cognitive complaints and 18 normal control su bjects. They were submitted to explicit and implicit memory tests and to tests claimed to be sensitive to frontal lobe dysfunction. The perf ormance of the 11 ACoa patients without cognitive complaints revealed evidence for a functional frontal dysfunction (test of Stroop) and a p artial deficit of explicit memory (free recall and long-term recall). The performance of the 7 ACoa amnesics revealed evidence for a functio nal frontal dysfunction and a deficit of explicit memory (safe in reco gnition). Anosognosia was also observed. The performance of all patien ts revealed the preservation of implicit memory in procedural tasks (s erial reaction time and mirror reading) as diencephalic and temporal a mnesia. The functionnal nature of the syndrome is discussed.