There is still no unified opinion on the best cortical approach for surgery of tumors in the lateral ventricular triangle, especially for the dominant hemisphere.
Currently, the main surgical approaches to the lateral ventricular triangle are the middle temporal gyrus approach, the superior parieto-occipital lobe approach, and the posterior transcallosal approach.
The more commonly used approaches are Olivecrona’s posterior cortical transection in the middle temporal gyrus and superior parietal lobule’s longitudinal transection in the posterior central gyrus. For example, the middle temporal gyrus approach is easy to expose the anterior choroidal artery and can cut off the tumor supplying artery at an early stage, but it is easy to damage the visual radiation, and there is a risk of aggravating the speech impairment in the dominant hemisphere. Therefore, the specific choice should be made according to the precise location, size and blood supplying artery of the tumor provided by imaging examination. If the lesion is located in the dominant hemisphere, there is no preoperative isotropic hemianopia, the tumor is relatively small or moderately large, and it is mainly supplied by the posterior lateral choroidal artery, the posterior transcallosal approach is preferred.
The posterior transcallosal approach: This approach was first reported by Kamp in 1976 with good results and is suitable for resection of tumors spanning the bilateral triangle and small intracerebroventricular tumors, and is easy to deal with the posterior choroidal artery.
Interparietal sulcus approach: Maurizio et al. used an incision over the parieto-occipital lobe, which is considered less likely to impair visual radiation and language function, but there is a risk of postoperative isotropic hemianopia.
Regarding the principles of selecting the surgical approach for lateral ventricular meningioma, the following factors should be grasped: ①Refer to the size and location of the tumor, the size of the ventricles, the direction of the blood supplying arteries and draining veins, the patient’s preoperative neurological dysfunction and possible postoperative neurological deficits; ②Large operating space, minimize cortical traction, expose the blood supplying arteries of the tumor as much as possible, and reduce bleeding during surgery; ③Obtain an (3) to obtain an optimal anatomical exposure of the tumor and blood vessels without damaging the neurological function or with only slight effects.
We believe that the main points of intraoperative attention: ① When the cortical incision is close to the main body of the tumor, the cortical functional area should be avoided as much as possible, because the parieto-occipital and temporal approaches pass through cortical areas with relatively minor functions, and these two approaches are chosen. ②When cutting the brain tissue and revealing the tumor, the operation should be gentle and protect the thalamic veins on the ventricular wall. ③Expose and treat the supply vessels of the tumor first as much as possible to reduce intraoperative bleeding. ④When the tumor is large, complete resection should not be forced, but can be done in pieces first, and the tumor can be broken up and removed by ultrasonic emulsion suction knife. This can not only make the operation less bleeding and safer, but also shorten the operation time. Because the oscillation amplitude of ultrasonic emulsion suction knife is 100~300 μm, therefore, the damage to the normal tissues around the lesion is very small, so it is more superior than using ordinary suction device or tumor clamp. In addition, it effectively protects the elastic tissue while aspirating the tumor, and can preserve the blood vessels with diameter >1 mm, so it can reduce bleeding and protect important blood vessels. ⑤ Stop bleeding thoroughly and flush repeatedly to prevent blood clots or gelatin sponges from remaining in the ventricles and blocking cerebrospinal fluid circulation. (6) Pay attention to protect the interventricular foramen with cotton sheets during surgery to avoid bleeding into the contralateral or third ventricle. (7) Tightly suture the dura mater to prevent cerebrospinal fluid leakage. Surgery for lateral ventricular meningioma is difficult and risky, but satisfactory treatment results can be obtained by choosing a reasonable individualized surgical plan according to the patient’s condition, careful intraoperative operation, and paying attention to protecting the ventricular wall and the surrounding important anatomical structures.