MR in the diagnosis of Wernicke-Korsakoff syndrome.

Wernicke disease, or Wernicke encephalopathy, is a neurologic disorder of abrupt or saltatory onset, characterized by nystagmus, abducens and conjugate gaze palsies , unsteadiness of stance and gait, confusion , and apathy. These manifestations may occur singly or in various combinations. Korsakoff psychosis (better termed Korsakoff syndrome or Korsakoff amnesic state) refers to an abnormality of mentation in which learning and memory are affected out of proportion to other cognitive functions ; the patient is otherwise alert and responsive. Most patients who present with the manifestations of Wernicke disease and survive the acute illness are left with an enduring amnesic state-in which case the term Wernicke-Korsakoff syndrome is appropriate. The syndrome is common; autopsy studies in disparate parts of the world (Oslo, Boston, Cleveland , and Western Australia) have shown a prevalence of between 2 and 3% of the adult population [1] . The Wernicke-Korsakoff syndrome is due to nutritional deficiency, more specifically to a deficiency of vitamin B1 , or thiamine. In the Western world , it occurs most often in alcoholics. Alcohol displaces food in the diet and also adds its own carbohydrate calories, thus increasing the need for thiamine. However, the syndrome is observed with some regularity in a wide variety of other medical settings: prolonged infectious-febrile conditions, carcinoma, hyperemesis gravidarum, small-bowel obstruction, anorexia nervosa, and prolonged voluntary starvationto name the better documented ones. Increasingly, in recent years, attention has been drawn to iatrogenic factors in the causation of the Wernicke-Korsakoff syndrome. From time to time, the syndrome is a complication of a prolonged course of dialysis or hyperalimentation. In a significant proportion of patients who have gastric partitioning or plication , for the treatment of morbid obesity, persistent vomiting and the Wernicke-Korsakoff syndrome develop. In confused alcoholics and otherwise nutritionally depleted patients, particularly those with other serious medical illnesses, the long-term administration of dextrose and water without supplemental vitamins may precipitate the syndrome or cause an early form of it to worsen. This is not an uncommon clinical event, even on the wards of teaching hospitals [2] and is all the more distressing because it can be prevented by the simple expedient of adding B vitamins to the parenteral fluids. Patients who die in the acute stages of Wernicke disease show symmetrical lesions in the para ventricular regions of the thalamus and hypothalamus, in the mamillary bodies, periaqueductal region of the midbrain , floor of the fourth ventricle (particularly in the regions of the dorsal motor nuclei of the vagus and vestibular nuclei) , and midline structures of the cerebellum. Histologically, the lesions are characterized by various degrees of necrosis, with prominence of blood vessels and a proliferation of astrocytic and microglial cells. Hemorrhages are found in only 20% of autopsied cases; they are usually petechial in size, and many of them appear to be agonal. In this issue of the AJNR, two separate groups of neuroradiologists [3 , 4] describe for the first time the MR appearance of the acute lesions of the Wernicke-Korsakoff syndrome. Bilaterally symmetrical diencephalic (medial thalamic) and mesencephalic (periaqueductal) lesions stand out with remarkable clarity, much more so than with CT scanning [5 , 6]. This is a matter of more than theoretical interest. If early signs and symptoms of the syndrome are not recognized ,