Acute epidural hemorrhage following burr-hole irrigation for chronic subdural hematoma: A possible association with the diploic veins.

A 50-year-old man presented with headache and left hemiparesis. No noticeable preceding head trauma was observed. Computed tomography (CT) scans revealed a compressive chronic subdural hematoma (CSDH). The patient underwent burr-hole irrigation, during which he was considerably restless. In addition, extensive avulsion was found in the parietal dura mater posterior to the burr hole. CT performed immediately after the surgery revealed the emergence of a thick epidural hematoma (EDH) located posterior to the burr-hole. During emergency craniotomy for the EDH, there was no identifiable injury to the dura mater or the meningeal vessels. However, a review of the CT scans confirmed well-developed diploic spaces just above the center of the EDH, with connecting channels between the diploic spaces and extracranial sites. Based on these observations, we assumed that the diploic vein might have caused the EDH. Diploic veins can cause AEDH after burr hole irrigation for CSDH. Appropriate intraoperative sedation and protective irrigation maneuvers can reduce the risk of such AEDH.