A 52-year-old man presented with acute onset of primarily anterograde amnesia. He had a history of diabetes mellitus, coronary artery disease and smoking. We found no other focal neurological deficits. The amnesia improved slowly over the subsequent weeks.
MR scan of the brain showed moderate chronic microangiopathic white matter changes and acute infarction in both fornices (figure 1). This most likely explained the abrupt onset of anterograde amnesia and prolonged recovery.
The fornixAnatomy and function
The fornices are white matter tract bundles that lie on the medial aspects of the cerebral hemispheres. They each contain output fibres arising from the ipsilateral hippocampus and form an arch beneath the corpus callosum. They then arch around the thalamus, and so connect the medial temporal lobes to the hypothalamus. Crossing fibres between the crura of each fornix form a commissure, sometimes known as the hippocampal commissure.1
The left fornix…