视放射显微解剖与颞叶切除术后视野缺损

目的 经过人尸脑内视放射纤维解剖,研究颞叶切除术后视野缺损的机制.方法 人尸脑标本冷冻2周以上用自来水融冻后作为解剖用标本.用显微神经外科手术技术从大脑外侧面由浅入深进行脑内神经纤维的解剖,其中视放射解剖经过用立体照相技术予以纪录.结果 视放射从外侧膝状体起始,途经颞叶和顶叶到达枕叶视觉皮质区.视放射中央束和部分后束纤维集中在侧脑室颞角后部的顶壁和房部前壁之内.成功解剖Meyer袢前界,Meyer袢最前方纤维部分向前伸入到杏仁核实质之内.侧裂点与脑岛后角位置相当,在侧脑室房部的外侧,并在外侧膝状体的上后方.结论 向后越过Meyer袢前界的损伤可导致术后视野缺损.因视放射最前部纤维伸入到杏仁核实质之内,所以颞叶切除术后视野缺损并发症几乎不可完全避免.术后视野缺损程度与视放射纤维受损程度呈成正相关,轻者为象限性盲,重者为偏盲;视野缺损严重者具有黄斑视力和后束纤维的损伤.

Study of mechanisms of occurrence and seriousness of visual field defects after temporal labectomy by microsurgical fiber dissection of optic radiations

Objective Try to understand more about the mechanisms of occurrence and seriousness of optic field defects after temporal labectomy by microsurgical fiber dissection of optic radiations in cadaveric brains. Method Specimens of cadaveric brains processed by Klingler's technique. The dissections of specimens were performed under microsurgical techniques in a superficial-deep stepwise way from lateral surface of cerebral hemispheres, and the dissected optic radiations made into a three-bundle structure. Every important step was photographed by a 3D photographing technique. Results Optic radiations originated in lateral geniculate body and took their courses in temporal, parietal and occipital lobes. The central bundle and part of the posterior bundle of the optic radiations concentrated in the roof of posterior temporal horn and in the anterolateral wall of the atrium of the lateral ventricle. It was possible to dissect out the anterior limit of the Meyer's loop rather than its posterior limit. It was found that the most anterior part of Meyer's loop pass in the essence of amygdale. The Sylvian point, which corresponds to the posterior angle of insula, was located lateral to the atrium and posterosuperior to the lateral geniculate body. Conclusions Injury to optic radiations over the anterior limit of Meyer's loop has a relation with the occurrence of visual field defects after temporal labectomy. The finding that the most anterior part of Meyer's loop passes in the essence of amygdale suggests that it is not possible to completely avoid postoperative visual field defects after partial or complete temporal labectomy, in which the amygdale should be removed for the treatment. The seriousness of postoperative visual field defects has the positive correlation with the extent of injury to optic radiation: partial or complete injuries to Meyer's loop would cause partial or complete quadrantanopias; injuries passing over posterior limit of it would cause partial or complete hemianopias; serious visual field defects with macular involvements suggest injuries to the macular fibers or central bundle of optic radiations. 3. The artificially dissected structure of three-bundle optic radiations is useful for stereoscopically understanding of the functional structure of optic radiations.