A case of failed awake craniotomy due to progressive intraoperative hyponatremia

BACKGROUND: Perioperative seizure control is correlated with a better surgical outcome for awake craniotomy, but some anticonvulsants can induce hyponatremia. Mannitol has also been reported to be hyponatremic. CASE PRESENTATION: A 51-year-old right-handed man had malignant glioma in the left parietal lobe. Since anticonvulsant polytherapy did not stop his seizure activity, the daily dose of carbamazepine was increased beginning 17 days before awake craniotomy. The last preoperative blood examination indicated that his plasma sodium level had gradually decreased from 140 to 130 mEq/L. Following skin incision, 200 mL of 20% mannitol was administered and his plasma sodium level subsequently dropped to 117 mEq/L. The surgical strategy was changed so that the entire procedure would be performed under general anesthesia because severe intraoperative complications were anticipated. CONCLUSIONS: This case suggests that a perioperative electrolyte imbalance caused by drug interactions could be clinically significant for awake craniotomy.