Are hippocampal lesions sufficient to cause lasting amnesia?

A 57-year-old woman developed severe generalised amnesia following an embolic stroke. The amnesia persisted until her death nine months later. The left hemisphere had a large infarction of the medial temporal-occipital region, while the right showed only a small infarct limited to the posterior two-thirds of the hippocampus. If bilateral lesions are necessary for the production of permanent amnesia, the findings support the view that the hippocampus is itself a critical structure in the medial temporal diencephalic memory circuit.