Early Localization and Preservation of Adjacent Neurovasculature

Whenever possible, any adjacent or nearby normal neurovasculature (e.g. a cranial nerve or a vessel) should be identified and dissection carried out following this structure into the tumor. For example, in large clinoidal tumors encasing the optic nerve and the ICA, the conventional technique for removal has been first to identify the distal middle cerebral artery branches, and follow these vessels proximally toward the ICA with further tumor removal and dissection. However, until the ICA, and eventually the intradural optic nerve, are located, surgery progresses slowly. More importantly, the risk of intraoperative neurovascular injury persists during surgery as the exact location of the optic nerve and ICA remains unknown to the surgeon, and the optic nerve remains compressed. During this time, any minor surgical trauma caused by retraction, dissection or tumor manipulation may exacerbate compression of the optic nerve, especially against the falciform ligament. To circumvent these critical problems, the optic nerve can be exposed and simultaneously decompressed early in the surgery by unroofing the optic canal, followed by anterior clinoidectomy and opening of the optic sheath [29] (Figs 12.3, 12.4, 12.5). The location of the optic canal, and therefore the intra-canalicular segment of the optic nerve, is fairly constant; only the intradural cisternal segment of the optic nerve varies in location, depending on how the tumor causes nerve displacement during its growth. The exposed optic nerve can then be followed from the optic canal proxi-mally, toward the tumor in the intradural location. As tumor resection progresses further, the ICA can be readily found adjacent to the exposed distal intradural segment of the optic nerve. Complete optic sheath opening, along the length of the nerve within the optic canal to the anulus of Zinn, relieves any focal circumferential pressure on the optic nerve contributed by the falciform ligament. Optic nerve decompression thus achieved also leads to reduced intraoperative injury to the nerve, because the force of retraction is then dispersed over a much larger surface area. Moreover, if the tumor eventually recurs, the patient's impending visual deterioration may be delayed as the optic nerve is already decompressed from the surrounding falciform ligament and optic canal. In the senior author's personal experience utilizing the described technique in eight patients presenting with pre-operative visual deterioration from large clinoidal menin-giomas, six patients (75%) experienced significant improvement in their vision post-operatively [29].

Whenever possible, no cortical vein or dural sinus is "sacrificed". Although the anterior third of the sagittal sinus is traditionally said to be amenable to obliteration without any significant sequelae, there is a risk of developing significant venous infarcts. Therefore, even in large olfactory groove or planum sphenoidale tumors, rather than routine anterior sagittal sinus obliteration following a bifrontal craniotomy, either a unilateral pterional or a bilateral interhemi-spheric approach with preservation of sagittal sinus is used whenever possible in the authors' practice. In parasagittal meningiomas, the tumor is removed aggressively, along with the involved segment of sagittal sinus, only when the sinus is completely occluded by the tumor. Otherwise, every effort is made to preserve the sagittal sinus integrity and patency while

Cure Your Yeast Infection For Good

Cure Your Yeast Infection For Good

The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.

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