Skull Base Surgery of the Posterior Fossa

211

cipital craniotomy exposes the posterior sulci of
the medulla, which can be used as a safe-entry
zone for resection of intrinsic medullary lesions.
When combined with resection of the posterior
arch of C1 and ligation of the dentate ligaments,
the suboccipital (or far lateral craniotomies) may
be used to approach more ventrally located lesions.

Outcomes of Microsurgery

Posterior Circulation Aneurysms

The treatment of posterior circulation aneurysms

has evolved greatly over the past two decades, in

large part due to the publication of two random-

Fig. 14.10 Retrosigmoid approach to a brainstem
AVM. A 58-year-old man suffered from a sudden onset
ptosis of the right eye. (a) Axial computed tomography
angiography demonstrates a tangle of vessels in the right
cerebellopontine angle. (b) Anteroposterior (AP) and (c)
lateral vertebral artery angiography demonstrates an AVM
of the lateral brainstem that is exophytic into the right cer-
ebellopontine angle cistern. Preoperative angiography
demonstrated two branches of the SCA and a single feeder
from AICA. The lesion was preoperatively embolized

using n-butyl cyanoacrylate glue. (d) AP and (e) lateral

angiograms demonstrate partial devascularization of the

AVM after embolization. The lesion was approached

using a right retrosigmoid craniotomy and resected in a

gross-total fashion. (f) AP and (g) lateral postoperative

vertebral artery angiography demonstrates complete

removal of the lesion. The patient was at his baseline post-

operatively (Used with permission from Barrow

Neurological Institute, Phoenix, Arizona)

14 Microsurgical Management of Posterior Fossa Vascular Lesions