[Hypothermia and the nervous system. Review of the literature apropos of 4 cases].

Thermoregulation involves a long term adaptation system with hormonal processes and an immediate regulation system by extrapyramidal tracts, sympathetic part of autonomic nervous system and cortical integration of body temperature changes. Both system are under control of a hypothalamic center. Prolonged accidental exposure to intense cold and myxoedematous coma are the best known etiologies of hypothermia. However milder and often misdiagnosed hypothermia can occur at home in patients without endocrinologic disease. In these cases, hypothermia is due to dysfunction of immediate thermregulation under neuronal control, especially somatomotor and autonomic system. We report four cases of hypothermia of this kind. Two patients had an inhibition of peripherical mechanisms of protecting against cold (cutaneous vasoconstriction, shivering) and had dampened perception of cold: one was 73, had diabetes mellitus and took different drugs, the other one suffered from systemic lupus with myelopathy. The two other patients probably had a disorder of the thermoregulation hypothalamic center: one had Wernicke's encephalopathy and the other multiple sclerosis. From these cases and a review of the literature, we describe the different etiologies of hypothermia and their pathophysiology.