THE SYNDROME OF INAPPROPRIATE SECRETION OF ANTIDIURETIC-HORMONE (SIADH) AS A CONSEQUENCE OF NECK DISSECTION

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH ) can have multiple causes. Surgical neck dissections may have an asso ciation with this syndrome and represent the basis for this study. A r etrospective review of 50 patients undergoing neck dissections was per formed to evaluate for the development of hyponatraemia as a consequen ce of SIADH. Based on the results of this review, a prospective study of 20 consecutive patients undergoing 22 neck dissections was performe d to determine the incidence of SIADH. A control group of 25 consecuti ve patients undergoing major non-neck dissection surgery was also stud ied. SIADH developed in nine of 50 patients (18 per cent) of our retro spective group with a high incidence of development in those who had j ugular vein ligation (JVL) (22 per cent), pre-operative radiation ther apy (25 per cent) or squamous cell cancers (32 per cent). SIADH develo ped in six patients undergoing 22 neck dissections (27 per cent) in ou r prospective group. A high incidence was also noted for those with JV L (42 per cent), pre-operative radiation therapy (67 per cent) or squa mous cell cancer (40 per cent). No patients developed symptomatic hypo natraemia. No patients in the prospective control group developed SIAD H. Neck dissection surgery is associated with a significant risk for t he development of SIADH. Factors such as jugular vein ligation (JVL), pre-operative radiotherapy and squamous cell cancer appear to increase this risk.