Korsakoff's syndrome resulting from bilateral fornix lesions.

A patient with a well-circumscribed neoplasm, which destroyed the posterior fornix bilaterally, developed a profound disturbance of recent memory. Unlike previously reported patients who had undergone anterior fornix sections and whose memories were not severely disturbed, this patient's posteriorly located lesion may have cut off hippocampal input into the mamillary bodies and the dorsomesial nucleus, thereby producing a severe amnestic state.