Fornix damage from solitary subependymal giant cell astrocytoma causing postoperative amnesic syndrome.

The amnesic syndrome is characterized by difficulty learning and recalling information, either previously encoded (retro-grade) or newly encountered (anterograde). Various structures within the medial temporal lobe and limbic system of the brain are thought to be important in memory formation and retrieval, as evidenced by the fact that damage to these areas may result in an amnesic syndrome (Papanicolaou, 2006). For example, anterograde amnesia associated with damage to the fornix (Sweet et al, 1959), a fibre bundle connecting the hippocampus to the mamillary bodies within the limbic system, is well described following removal of third ventricle colloid cysts (Hodges and Carpenter, 1991; McMackin et al, 1995; Aggleton et al, 2000), suggesting the importance of the fornix as one of the anatomical substrates of the distributed neural network underpinning memory functions (Mesulam, 1990). This article reports the cognitive impairments associated with left fornix damage which became apparent following surgical removal of a solitary subependymal giant cell astrocytoma.