Differentiation between brain lesions in experimental thiamine deficiency.

Dietary deprivation of thiamine combined with pyrithiamine administration in rats was used for pathophysiological and morphological investigations. The animals passed through three different symptomatic stages, ranging from slight neurological abnormalities to generalized seizures from day 8 up to day 11. Hypothermia was a consistent finding during the second week. Histological examination revealed two types of neuropathological lesions in the rats. Those in the colliculi inferiores and the vestibular nuclei were characterized by a bullous spongiform appearance of the neuropil with severely damaged, pale and oedematous nerve cells. Alterations in the thalamus and inferior olives, however, showed eosinophilic nerve cell necrosis of the ischemic type which resembles the thalamic pathology found in human cases of Wernicke's encephalopathy.