Hippocampal calcification

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Hippocampal calcification is a common incidental finding of uncertain clinical relevance in older patients. It is frequently overlooked as it can be mistaken for choroid plexus calcifications.

Epidemiology

Hippocampal calcification can be encountered in up to 20% of individuals over 50 years of age and its prevalence increases with age . Additional risk factors include diabetes mellitus and smoking .

Clinical presentation

Clinical significance of hippocampal calcification remains uncertain. Small case control series have shown significantly greater cognitive decline and lower MMSE score in patients with hippocampal calcification compared to controls but to date this has not been validated in larger population studies .

Pathology

Hippocampal calcification has been hypothesized to be related to vascular fibrosis and calcification leading to neural loss in affected individuals . This process tends to be limited to the hippocampal tail and infrequently progress to involve the head and body . Microvascular calcifications are located in the walls of precapillaries and capillaries in the vascular territory of the middle hippocampal artery. In more extensive cases, there is associated neuronal loss in the region of the dentate nucleus, CA1 of the hippocampal proper and subiculum .

Radiographic features

Non-contrast enhanced CT scan of the head is most sensitive in the detection of hippocampal calcification, especially with the use of thin slices and multi-planar reformats. Depiction of these tiny punctate calcifications on MRI is challenging even with the more sensitive susceptibility weighted imaging (SWI) sequence.

Differential diagnosis