Assessment of optic nerve decompression efficiency in resection of sellar region meningiomas via intradural subfrontal approach.

In this article we analyze results of the different variants of the optic nerve transcranial decompression in cases with different chiasmal region tumors. We operate 70 patient with different type meningioma (tuberculum sella, shenoid wings, anterior clinoid, optic canal), pituitary adenoma and one case with tuberculoma (we operate it thinking on meningioma, but histology was unexpected). Groups of the patients. Group1. 20 patients with pituitary adenoma with cavernous sinus invasion. It was our "pre-endoscopic" period when we frequently operated adenomas by transcranial approach. In this 20 patients we used intra-extradural Dolenc approach to cavernous sinus. In that cases we removed anterior clinoid process and decompressed optic canal. Here we use the results of surgery in this group for showing the possibility of using high speed drill for the optic canal decompression - for showing it safety. On our opinion this type of optic canal decompression is radical and safe but superfluous for the optic canal invasion by the meningioma. Group 2. 19 patients with meningioma. In that cases we partially unroofed optic canal by Kerrison and additionally we cut the falciform ligament. Group 3. 31 patients with meningioma. It's our "main" group. Here we made intradural wide unroofing the optic canal by high speed drill. Additionaly we cut the falciform ligament and open the dural sheet of the optic nerve. We propose this methodic like sufficient, safe and useful. In this cases we frequently saw the tumor spread inside the dural sheet of the optic nerve, without seeing it on the MRI. A lot of cases in this group was a recurrent after previous meningioma removal. Like a control groups we use two. Group 4. 11 cases with meningioma. In that cases we removed tumor from optic canal without any decompression. It was our archive group - we made this type of surgery before starting optic canal decompression. This group shows the risks of any manipulation with fixed optic nerves without optic canal decompression. Group 5. 31 case with meningioma. In this cases we saw the optic canal invasion by the tumor but we didn't try to decompress it. It was our archive group - we made this type of surgery before starting optic canal decompression. We use this group for found out the risks of canal decompression. This group shows the poor perspectives for the vision in optic canal invasion by the tumor without it decompression. We analyze the results of surgery on the day of discharge and on catamnesis - we decide that the optic nerves need time to recovery. We analyzed the results of surgery in patients with 3 types of the visual dysfunction: moderate (1.0-0.5), hard (0.5-0.1), decompensating (0.1-0). For showing the real risks and effectivety of any type of decompression and surgery without decompression we look for results in patients with decompensating of visual functions. For statistical analyses we use Fisher criteria which used in small series. We statistically showed that any attempts of tumor removal form the optic canal is more risky than decompression. Also we found a tendency that wide intradural decompresstion made by high speed drill with additional falciform ligament cutting and the dural sheet opening is more effective and safe than opening the optic canal by Kerrisson. This technique also could be used during the transcranial surgery for the other type of pathology particularly in cases with short optic nerves and prefixed chiasm - it gives the mobility for the nervesand decreased the nerve damaging.