中大脳動脈瘤に対する標準的外科治療

抄録

Many middle cerebral artery (MCA) aneurysms tend to be treated with direct clipping rather than coil embolization because of their anatomical characteristics and location. In the surgical treatment of MCA aneurysm, a standard pterional approach and distal trans-sylvian approach are performed. The standard pterional approach can provide wide exposure of the whole M1 segment of the MCA, including IC bifurcation, in which the parent artery is can be easily controlled, while the transsylvian approach may be performed for distally located small MCA aneurysms following a less invasive small craniotomy.

When the sylvian fissure is dissected, the arachnoid membrane should be sharply dissected preserving the pia mater and vascular structure between the frontal and temporal lobes. The counter pressure and choice of correct plane between the sylvian veins are keys to appropriate wide opening of the sylvian fissure. The obliteration of the dome of the aneurysm occasionally needs a combination of multiple clip applications to eliminate the pathological wall from systemic circulation. To prevent perforating artery obliteration and avoid branch occlusion, indocyanine green videoangiography, Doppler ultrasound sonography, and motor evoked potential are useful.

In the case of severe subarachnoid hemorrhage with sylvian hematoma, prophylactic external decompression prevents brain herniation. However, we should pay attention to the risk of paradoxical brain herniation after external decompression when lumbar spinal drainage is placed.