Abstract
The timing of surgery for cerebral aneurysms in the vertebro-basilar system is still controversial. In this paper, we describe our surgical technique for acute surgery for the VA-PICA aneurysm, and also put forward the question of whether we should remove the supratentorial subarachnoidal clot through a new supratentorial craniotomy, after the neck-clipping of the VA-PICA aneurysm, to prevent a delayed vasospasm.
We use a supine-lateral position, the neck is extended and flexed, and incise the skin from 2cm above the inion downward to the level of C4-C5 and 2cm medial to the mastoid process (retroauricular-retromastoidal skin incision). We make a paramastoidal craniectomy, exposing the sigmoid sinus and opening the foramen magnum. We open the dura first at the cistena magna to let the CSF flow out and then extend the dural incision, so as not to injure the cortex of the cerebellum during dural opening.
The PICA comes out through the lower cranial nerves. It is easy to find the origin of the PICA, following its lateral medullary segment. The proximal and distal portions of the vertebral artery are exposed without difficulties if we approach parallel to the posterior surface of the pyramis of the temporal bone. During dissection and clipping of the aneurysmal neck, care must be taken not to injure the hypoglossal nerve, since this nerve usually contacts the aneurysm. After the clipping is finished, we remove as much of the subarachnoidal clot as possible using an irrigation-suction system.
With the suboccipital approach we do not usually place a cisternal drain, in order not to develop a subcutaneous CSF collection. Instead, immeadiate-postoperatively, we place a lumbar drain to remove the bloody CSF. Dural plasty is made using a lyodura.
In the acute surgery of the VA-PICA aneurysm, it is important to make a rather large craniectomy or craniotomy including opening the cisterna magna in order to perform the clipping easer, to remove as much of the subarachnoidal clot as possible and to prevent possible delayed vasospasm.
