The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) following neck dissection.

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is characterized by hyponatremia and urinary osmolality generally greater than serum osmolality. It is due to inappropriate water retention resulting from excessive release of antidiuretic hormone (ADH). Seventeen patients undergoing neck dissection were studied. Six developed SIADH and two became symptomatic due to profound hyponatremia. Five of the six patients who developed SIADH had previously undergone a neck dissection and/or had received radiation therapy. A suggested pathophysiologic mechanism for this phenomenon is discussed. The syndrome can usually be prevented by fluid restriction during and after surgery.