Successful Endoscopic Resection of a Chronic Expanding Hematoma Following Gamma Knife Surgery for Cerebral Arteriovenous Malformation: A Case Report.

Gamma knife surgery is useful for treating cerebral arteriovenous malformations. However, some radiation-induced long-term complications have been reported. One of these is a chronic expanding hematoma. We present a case of chronic expanding hematoma, successfully treated with endoscopic resection. The patient, a woman in her 30s, experienced a cerebral hemorrhage 17 years ago associated with an arteriovenous malformation in the corpus callosum. The lesion was completely embolized with n-butyl-2-cyanoacrylate embolization twice, followed 2 years later by gamma knife surgery. The patient presented to the emergency room with headache and left hemiplegia. A computed tomography scan showed hemorrhagic changes consistent with the cystic lesion and worsening edematous changes around it. An endoscopic tumor resection (interhemispheric approach) was performed, and most of the lesion was removed. Pathology did not detect any neoplastic lesions, and a diagnosis of chronic expanding hematoma was performed based on the presence of abnormal vascular neoplasia. The postoperative course was uneventful, and the headache promptly resolved. The pathophysiology of chronic expanding hematoma involves slow and progressive hematoma expansion due to repeated local hemorrhage, causing intense cerebral edema around the lesion. Surgical removal is effective, and edematous changes and neurological symptoms can be quickly relieved after surgery. Endoscopic surgery is particularly effective for deep lesions owing to its ability to manipulate within a narrow surgical field. In this case, the lesion was removed with minimal invasiveness and no complications, leading to early symptom relief and resolution of the surrounding brain edema changes.