Recovery of anterograde amnesia in a case of craniopharyngioma

Background: Studies of the amnesic syndrome have indicated that telencephalic and diencephalic structures are critical components of the memory system. The exact role of the mammillary bodies (MBs) in human memory remains elusive, since few cases of selective MB damage have been reported. Objective: To study a case of severe anterograde amnesia due to a third-ventricle craniopharyngioma with severe MB compression. Design: Case report. Setting: Neurosurgery clinic of an academic hospital. Patient: A 53-year old woman who developed severe anterograde amnesia due to a third-ventricle craniopharyngioma strongly compressing the MBs and, to a lesser extent, the right hippocampus. Interventions: Surgical excision of the tumor and neuropsychological testing and positron emission tomography during an associative memory test before and 2 months after tumor removal. A postsurgical magnetic resonance image did not show evidence of damage to the hypothalamus, thalamus, hippocampus, or MBs. Main Outcome Measures: Changes in brain imaging data and results of neuropsychological testing. Results: After tumor removal, the patient showed a complete recovery of memory functions. Performance on the associative memory test was at chance level before surgery and dramatically improved postoperatively. Results of the preoperative positron emission tomographic study showed no activity in memory-related structures. In contrast, a significant blood flow increase occurred in the anterior thalamic nuclei postoperatively. Conclusions: These behavioral and brain imaging data stress the importance of the MBs in this patient's amnesia. Our data further suggest that the clinical prognosis of decompressing the mammillothalamic tract is excellent, even in cases of massive compression.