Neuroendoscope-assisted removal of an organized chronic subdural hematoma in a patient on bevacizumab therapy--case report.

A 78-year-old Japanese man with a history of colon cancer was referred to our department of neurosurgery for the management of asymptomatic left chronic subdural hematoma (CSDH). He was receiving bevacizumab therapy for colon cancer, and the size of the CSDH increased or decreased depending on bevacizumab administration. Simple drainage was performed because of the risk of a critical increase in the size of CSDH during bevacizumab therapy, but since the CSDH was organized and firm, the drainage was insufficient. Therefore, neuroendoscope-assisted craniotomy was performed, and the organized CSDH was almost completely removed. The present case indicates the possible involvement of bevacizumab in the occurrence of CSDH and the efficacy of the neuroendoscopic approach in the surgical treatment of organized CSDH.