Retrosplenial amnesia.
A 39-year-old man developed retrograde and anterograde amnesia following haemorrhage from an arteriovenous malformation situated near the splenium of the corpus callosum. MRI studies demonstrated damage to the splenium, and to a region containing the retrosplenial cortex and the cingulate bundle. The fornix was anterior and inferior to the site of maximal damage, but may have been involved; the stria terminalis was probably spared. Structures known to be important in memory but spared by the lesion included the hippocampus, thalamus, and basal forebrain. The retrosplenial cortex receives input from the subiculum and projects to the anterior thalamus, thus providing an alternative route between hippocampus and thalamus. Perhaps more importantly, medial temporal structures involved in memory receive anterior thalamic input directly via the cingulate bundle and indirectly through a relay in the retrosplenial cortex. We suggest that this thalamocortical portion of Papez' circuit may be important in memory, and that lesions of the cingulum and retrosplenial cortex may cause amnesia by disrupting this pathway.
Valenstein
E
E
Department of Neurology, University of Florida College of Medicine, Gainesville 32610.
Bowers
D
D
Verfaellie
M
M
Heilman
K M
KM
Day
A
A
Watson
R T
RT
D000328:Adult; D000647:Amnesia / Q000209:etiology* / Q000503:physiopathology; D001921:Brain / Q000473:pathology; D002533:Cerebral Angiography; D002543:Cerebral Hemorrhage / Q000150:complications* / Q000000981:diagnostic imaging; D003337:Corpus Callosum / Q000473:pathology; D005500:Follow-Up Studies; D006179:Gyrus Cinguli / Q000473:pathology; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000150:complications* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D014057:Tomography, X-Ray Computed