Electrolyte disorders after endoscopic transnasal neurosurgical interventions

Background: Disorders of water and electrolyte balance, hyper- and hyponatremia, are common postoperative complications of transsphenoidal neurosurgical interventions and are found in up to 30–40% of cases. At the same time, delayed hyponatremia is the main cause of repeated hospitalizations of patients, and the risk factors/pathogenetic mechanisms responsible for the development of postoperative hyponatremia have not been fully investigated. Aim: To determine the frequency of water-electrolyte disturbances and to identify predictors of dysnatriemia states in patients after transnasal adenomectomy. Materials and methods: A retrospective single-site study included an analysis of electronic medical records of patients who underwent transnasal neurosurgical interventions for benign tumors of the pituitary gland ( n = 416). The diagnostic and prognostic factors for the development of postoperative water-electrolyte disorders were evaluated. Results: The prevalence of hyponatremia in the total group of patients was 7.2%, and for hypernatremia it was 3 times higher – 24.3%, with these indicators being kept stable through the years of surgery ( p > 0.05; χ 2 with the Yeats correction). 66 (16%) of the operated patients, the sodium level in the early (0–5 day) and 157 (38%) patients in the later (6+ day) postoperative period was not determined, which may underestimate the identification of the most dangerous delayed postoperative hyponatremia. When analyzing the main clinical and laboratory characteristics of patients with hypo-, normo- and hypernatremia, no statistically significant differences were found between the parameters characterizing natremia, the osmolality of blood and urine, the frequency of determining blood sodium in different time intervals of the postoperative period. Complications of the main diagnosis (diabetes mellitus, coronary heart disease and arterial hypertension), selected parameters of pathological examination (identification of neurohypophysis cells, adenohypophysis, oxyphilic, basophilic or chromophobic cells, as well as other structures that are not part of the pituitary gland) and the operation protocol (bleeding, coagulation of sellar structures, liquorrhea, excision of the pituitary gland), did not differ between groups. In the hypernatremia group, the tumor volume in quantitative representation was lower than in the normo- and hyponatremia groups (1.0 ml vs. 1.5 and 1.5 ml, respectively). The number of neurosurgical interventions performed in a patient did not differ between the study groups. Conclusions: After transnasal adenomectomy, hypo- and hypernatremia occur in 7.2% and 24.3%, respectively, and do not depend on the presence of complications of the underlying disease, the parameters of the pathomorphological protocol, the appearance of postoperative hypopituitarism or the course of the operation itself. For the timely detection of disorders of water and electrolyte metabolism, the implementation of blood sodium testing in the early and late (6+ day) postoperative period is necessary in management of patients after transnasal adenomectomy.