Falx Meningioma Developed Cerebral Herniation Symptoms Approximately 6 Hours after the Onset of Headache: A Case Report and Literature Review.

Meningiomas are benign tumors outside the brain parenchyma that usually progress slowly but occasionally develop suddenly. We report a 40-year-old woman who presented with symptoms of cerebral herniation within a few hours of the onset of a headache. She felt no particular change until going to bed, when she noticed a headache, vomited, and fell into a coma. At the time of admission, she had a large anisocoria on the right side. A computed tomographic scan revealed a tumor of more than 6 cm in the right frontal region, and cerebral angiography showed tumor staining in multiple branches of the anterior cerebral artery. Intracranial perfusion was slow, suggesting severe intracranial hypertension. An emergency craniotomy was performed, and severe brain swelling was found after the dural incision, requiring an additional craniotomy. The tumor was prone to bleeding, which prolonged the operation time; consequently, the tumor was only partially removed and external decompression with duraplasty was required. After the cerebral swelling improved, tumor-feeding vessel embolization was performed, and then the remaining tumor was completely resected. The pathological diagnosis was atypical meningioma. Eleven months after surgery, the patient can walk by herself despite sensory impairment on the left side, and there has been no evidence of tumor recurrence. Emergency surgery may be required for meningiomas and may have to be performed in a situation where preoperative examinations are not sufficient. In such situations, it is desirable to select an appropriate surgical procedure, including two-stage surgery, and to perform prompt treatment.