Objectives/hypothesis: The syndrome of inappropriate antidiuretic hormone or arginine vasopressin secretion (SIADH) is a disorder in which release of antidiuretic hormone is independent of plasma osmolarity, resulting in fluid retention and development of dilutional hyponatremia. The incidence of SIADH following neck dissection was found to be 18% to 30% in two separate reports. The incidence of SIADH in a cohort of patients who underwent neck dissection was prospectively studied.
Methods: Eighty-six patients were included in the study, along with a control group of 19 patients who underwent other neck procedures. Patient gender, age, physical condition (American Society of Anesthesiologists score), type of neck dissection, prior treatment, and smoking history were noted. Blood and urine osmolarity and sodium levels were sampled before surgery and during the first 24 hours after the surgery. These were recorded daily in cases with SIADH until the syndrome resolved.
Results: The incidence of SIADH was only 1.15% in patients before surgery. The syndrome developed in seven patients following neck dissection (8.14%) and in none of the patients in the control group. SIADH resolved within 72 hours at the latest. No association was found with patient gender, age, physical condition, or type or laterality of neck dissection. A statistically significant connection between the syndrome and history of smoking was noted (P <.05), and it was more commonly seen in patients with node-positive necks (P =.1231).
Conclusions: SIADH following neck dissection may be less common than formerly reported. Previous studies have presented contradicting data concerning the influence of tumor recurrence or prior radiation therapy on its incidence. Our results indicate no such association. A statistically significant connection between smoking and the syndrome was found. No clinical symptoms developed in the patients with SIADH, but it seems prudent to suggest limiting fluid intake in the first postoperative 24 hours for patients following neck dissection.