[Study of small dural window exposure strategy for preventing intraoperative acute brain herniation during removal of huge intracranial meningiomas].

Objective: To investigate and assess the value of small dural window exposure strategy on preventing brain herniation during the operation for huge intracranial meningiomas.
Methods: Different classical operative approaches were used for the removal of intracranial meningiomas situated in different locations. When the dura was found to be under high tension, it was imperative that measures should be taken to prevent damage to the brain tissue in the important cortical areas as a result of acute intraoperative brain swelling and herniation. The strategy to be taken was to make a small dural window for exposure, thus the dura was used as a natural barrier to prevent acute brain swelling and herniation. The concept was to tailor the location and size of the dural opening to the location and size of the tumor, so that through the window only a part of the tumor was exposed, without exposing any important structures, such as bridging veins to the sagittal sinus and middle cerebral artery in the Sylvian fissure or any part of brain tissue initially. When necessary only a part of non-important brain tissue adjacent to the tumor could be exposed. Through this small dural window a huge tumor could be removed piecemeal till the high pressure under the dura was relieved. Then the dura could be opened more to remove the whole tumor.
Results: In 6 consecutive cases with extremely high tension under the dura, total tumor removal was successfully performed with complete avoidance of the risk of acute intraoperative brain swelling and herniation, and all the patients had uneventful recovery, and they were able to resume normal life. The locations of the said tumors were: in parasagittal falx region in 2 cases, and 1 case each in sphenoid, cerebellopontine angle, middle cranial fossa and temporal convexity region.
Conclusion: The small dural window exposure strategy can guarantee safe total removal of huge intracranial meningiomas avoiding the risk of acute intraoperative brain swelling and herniation. Peritumorous brain tissue can be kept intact. Preoperative spinal drainage of cerebrospinal fluid for lowering intracranial pressure is unnecessary in the majority of such cases. Some new knowledge for our understanding the etiological mechanisms and the mechanisms of the surgical strategy to avoid acute intraoperative brain swelling and herniation in removal of huge intracranial meningiomas can be learned.