A case presenting with retro-orbital pain during endoscopic burr-hole surgery for organized chronic subdural hematoma

Surgery for organized CSDH with long-term brain compression requires inner membranectomy. However, rapid decompression by aggressive membranectomy increases the risk of intracranial hemorrhage and mortality, and it is often difficult to determine how much of the membrane should be excised. In the present case, the abrupt increase in cerebral blood flow (CBF) may have resulted in hemorrhage, and this could have been avoided if the surgery had been performed in two stages. Retro-orbital pain suggests excessive CBF increase and could be a warning sign to stop surgery immediately.