Hyponatremia after craniotomy can be associated with increased morbidity. Risk factors for post-craniotomy hyponatremia in children are not known. The objective of this study was to determine the incidence of hyponatremia after craniotomy in children and to identify associated risk factors.Methods: We performed a retrospective cohort study of patients 0-21 who underwent initial craniotomy in 2017 - 2019 at a single center. Indications for craniotomy included tumors, epilepsy, infection, trauma, craniofacial, Chiari decompression, and vascular. Children who had surgery for craniopharyngioma were excluded since that is commonly associated with pituitary dysfunction and sodium abnormalities. Hyponatremia was defined as a serum sodium level ?135 mEq/L any time during the postoperative hospital stay. Data on demographics, surgical information, and lab values were tested for association with postoperative hyponatremia using univariate and multivariate logistic regression. Statistical significance was defined as p < 0.05.
Postoperative hyponatremia occurred in 61 (25%) of 240 children. On univariate analysis, hyponatremia was associated with younger age (8.5 vs 6.3 years, p = 0.01), government/private insurance (p = 0.04), pre-existing hydrocephalus (p = 0.04), pre-operative anti-epileptic drugs (p = 0.02) and blood transfusion (p = 0.02). On multivariate analysis, only hydrocephalus (OR 2.85, 95% CI 1.07- 7.60) remained significant. Hyponatremia most commonly occurred on the first postoperative day, with patients recovering in a median of 14 (IQR 9.8 24.3) hours. Hyponatremia was also significantly associated with longer length of stay (median 8 vs 3 days, p < 0.01).
Hyponatremia developed in 25% of children after craniotomy. Pre-existing hydrocephalus was the most important risk factor in developing hyponatremia after initial craniotomy.