Oxcarbazepine-induced syndrome of inappropriate antidiuretic hormone secretion in a trigeminal neuralgia: A case report

Hyponatremia is the most common electrolyte abnormality encountered in neurosurgical practice. The pathophysiology for hyponatremia among neurosurgical patients is most commonly due to syndrome of inappropriate antidiuretic hormone secretion (SIADH). SIADH is the most common cause of euvolemic hyponatremia. There are various causes of SIADH ranging from drugs to malignancies. Among neurosurgical patients, it is described in subarachnoid hemorrhage, traumatic brain injury, pituitary surgeries, postoperatively after intracranial insult, and rarely in association with other intracerebral pathologies. The diagnostic criteria for SIADH include hypoosmolality, elevated urinary osmolality, euvolemia, and elevated urinary sodium which was present in our case. Our patient was diagnosed with trigeminal neuralgia due to CP angle epidermoid and was on T. Oxcarbazepine 300 mg daily since 6 months for the neuropathic pain. History and physical examination were unremarkable except for serum sodium of 118 mEq/L. Though the possibility of intracranial tumor may be the cause of SIADH, which is very rare due to the tumor location; hence, the possible explanation for the asymptomatic hyponatremia in this patient may be due to oxcarbazepine-induced SIADH. Here is a case report of SIADH due to oxcarbazepine and its perioperative management in a 24-year-old woman diagnosed with trigeminal neuralgia.