A rare but serious case of subdural hematoma following transsphenoidal surgery for a pituitary adenoma

• Acute subdural hematoma (ASDH) is a rare but critical complication of transsphenoidal surgery (TSS). • Severe hypernatremia may contribute to spontaneous ASDH post-TSS, even with minimal cerebrospinal fluid (CSF) leakage. • Early recognition and prompt surgical intervention are essential to prevent severe neurological outcomes. • This case report provides a valuable instance of ASDH associated with severe hypernatremia and minimal cerebrospinal fluid (CSF) leakage following TSS. Transsphenoidal endoscopy is a prevalently performed surgical procedure aimed at removing pituitary lesions. This procedure can lead to various complications, including CSF leakage, tension pneumocephalus, and hypernatremia following the removal of a pituitary adenoma. In this particular case, we present a patient with a pituitary adenoma who unexpectedly got a spontaneous subdural hematoma (ASDH), nine days after undergoing transsphenoidal surgery, despite having a minor CSF leak. We speculate that this complication was linked to severe hypernatremia and a sudden decrease in consciousness level, necessitating immediate surgical intervention for hematoma removal. this case represents the first reported instance of ASDH associated with severe hypernatremia and negligible CSF leakage.