[Incidence of inappropriate secretion of antidiuretic hormone in patients with severe head injuries].

Eight patients with severe craniocerebral trauma were studied prospectively to assess the effects of the injury on sodium and water balance. Hyponatremic hypo-osmolar states occurred in 5 of the 8 patients. The cause was an inappropriate secretion of antidiuretic hormone (I.S.A.D.H.). We found an early I.S.A.D.H. (appearing within 2-3 days post trauma) whose presence was related to the craniocerebral injury (2 cases). We also found a late I.S.A.D.H. which may represent a response to positive-pressure ventilation, semi-recumbent position and centrally acting drugs. This tardive I.S.A.D.H. appeared 9-10 days after admission (3 cases). Radioimmunoassay for circulating and ventricular C.S.F. neurophysins shows an early and transitory increase of hNpI (the carrier of A.D.H.). hNpI was detectable during the hyponatremic hypo-osmolar states, thus demonstrating an inappropriate secretion of A.D.H.