颞叶白质纤维束及相关结构的显微解剖学研究

目的 对颞叶白质纤维束及相关结构进行显微解剖学研究,分析其功能及临床意义.方法 选取100 g/L甲醛固定的国人成年尸体头颅标本10例(20侧大脑半球),在4～25倍手术显微镜辅助下,运用Klingler纤维剥离技术,解剖剥离大脑半球,观察颞叶白质纤维束及相关结构.结果 颞叶内存在大量复杂的白质纤维束,在侧脑室颞角周围尤为复杂.在颞角外侧由外向内依次有上纵束的垂直部、颞枕桥束、枕额下束、视辐射前中束.在颞角顶部上方由上向下依次有最外囊与外囊的颞盖部分、听辐射、钩状束、颞枕桥束出内囊的部分、部分枕额下束、前连合、视辐射前中束(包括Meyer's环)、脑脚袢、终纹.胼胝体放射组成侧脑室颞角外侧壁,其顶壁主要由尾状核尾及终纹构成,杏仁核组成颞角尖的前壁、上壁及内侧壁,海马构成侧脑室颞角的内侧壁.脑脚袢是侧脑室颞角内侧的一个重要结构.结论 颞叶内存在大量的白质纤维束,在侧脑室颞角尤为复杂,了解颞叶白质纤维束及相关结构的解剖特点,能够对颞叶部位的手术提供理论指导,减少手术并发症,降低手术致病率.     

颞叶切除术后视觉障碍的原因分析和预防

目的分析颞叶癫痫患者颞叶切除术后出现视觉障碍的原因,改进手术方法,以进一步提高手术疗效,减少术后视觉障碍并发症的发生。方法通过熟悉与视觉相关的颞叶解剖,改进治疗颞叶癫痫患者前颞叶切除术的技术。①针对滑车神经和动眼神经损伤所致的复视,在切除颞叶内侧结构时,在软膜内切除,避免双极电凝的热损伤。②针对视放射损伤导致的视野缺损,离断颞叶的范围距颞极不要超过3.5cm。结果 42例颞叶癫痫患者颞叶切除术后仅2例出现复视,其余没有视野缺损症状。39例随访7～26个月,癫痫发作控制达到EngelⅠ～Ⅱ级者31例(79.5%),Ⅲ～Ⅳ级8例。3例失访。结论颞叶癫痫患者颞前叶切除术后出现复视和视野缺损的主要原因是手术中滑车神经、动眼神经和视放射受损。手术中严格限制切除颞叶范围,防止视放射受损和良好的显微外科操作技巧,避免损伤动眼和滑车神经,可以有效防止术后视觉障碍并发症的发生。     

岛叶区白质纤维解剖研究

目的 研究岛叶区域解剖及经岛叶入路,为临床手术提供指导.方法 对15例尸头进行解剖研究,其中5例行白质纤维解剖研究.对10名健康志愿者进行弥散张量纤维束成像(DTT)研究.结果 颞干主要由钩状束、额枕下束、前连合及视辐射构成.打开外侧裂可暴露岛叶,在下环岛沟做一切口可进入侧脑室颞角,打开脉络裂颢部能到达中脑周围池,可暴露脚池后部、环池及四叠体池前部.结论 经岛叶入路可用于处理基底节区、颞叶内侧、中脑周围池病变.术中需注意保护颞干,DTT可更好地指导手术.     

前颞叶切除范围与视野缺损关系的弥散张量成像分析

目的 观察颞叶癫痫患者前颞叶切除术后视野缺损的发生率以及手术切除范围与视野缺损的关系.方法 25例前颞叶切除术的患者于术前及随访时行视野、磁共振(含DTI弥散张量序列)检查,根据视野缺损严重程度的不同将患者分为A、B、C三级.手术后视放射的各向异性分数(FA值)的下降(△FA)代表Meyer袢受损情况.比较不同视野缺损组之间前颞叶切除范围的差异;并对切除范围和△FA进行线性相关分析.结果 前颞叶切除术后22例患者出现象限盲.前颞叶平均切除长度:A组31.1 mm,B组42.5 mm,C组50.4 mm,A＜B＜C组(P＜0.05).手术侧的△FA与切除范围旱线性相关.结论 前颞叶切除术破坏视放射导致视野缺损较常见.有必要术前应用DTI获得患者视放射的信息,进行术前风险评估.

Abstract：

Objective Anterior temporal lobectomy(ATL) for temporal lobe epilepsy (TLE) is the most commonly performed epilepsy surgery procedure.A visual field defect(VFD) due to the injury to the optic radiation may occur after ATL.DTI technique can visualize the optic radiation (OR) noninvasively.This study aimed at evaluating the incidence of VFD after ATL and investigating whether the resection size of lateral ATL correlated with the extent of VFD.We tried to explain the impact of ATL on the OR and to investigate the anterior extending of Meyer loop with DTI technology.Method 25 patients( 14male, 11 female) underwent ATL for treatment of epilepsy.The patients were aged from 13 to 39 years old ( mean age:22.4 yrs).All cases were classified into three groups on the basis of the severity of VFD( A ～ C,with group C the most severe).All patients had preoperative and follow up clinical and MRI( including DTI series) examinations.The clinical and MRI(DTI) outcomes of these patients were retrospectively analyzed.Results At mean follow up period of 31.3 weeks ( range, 17 - 42 weeks), we found 22 patients become quadrantanopia due to the injury to OR after ATL.A significant reduction of fractional anisotropy was demonstrated in the OR on the side of the temporal lobectomy.The severity of VFD decreased according to the reducing of the mean resection size(group A, 31.1 mm;group B 42.5 mm;C, 50.4 mm), P ＜0.05.There was linearship between the resection size and the FA decrease.Conclusions VFD due to the injury to the OR was not uncommon after ATL There was an association between the resection size and severity of VFD.Optic radiation showed a decreased FA value in cases after ATL.There is considerable intersubjective variance about the OR, so it is necessary to get the patient's DTI information about the OR before the operation ,which could help to assess the preoperative risks.     

经颞下沟选择性杏仁核海马切除术治疗内侧颞叶癫痫

目的探讨经颞下沟侧脑室入路选择性杏仁核海马切除术治疗内侧颞叶癫痫的手术方法、效果及并发症。方法确诊为药物难治性内侧颞叶癫痫的30例患者,在无框架神经导航指引下,经颞部锁孔开颅,显微镜下分开一小段颞下沟,切开侧脑室壁,进入颞角前外侧区,选择性切除杏仁核海马。结果30例患者术后随访至少2年时间（24—59个月）,神经功能改善,无严重手术并发症,23例（76．7％）癫痫发作完全消失（EngelⅠ级）。结论经颞下沟侧脑室入路选择性杏仁核海马切除术是治疗内侧颞叶癫痫的有效方法,在神经导航辅助下手术创伤小,可妥善保护语言区和视放射,安全性高。     

杏仁核及其临床

一、杏仁核的解剖和生理功能杏仁核又称杏仁样核、杏仁样复合体,属于嗅脑皮质下结构或边缘系统皮质下结构.杏仁核的解剖位置因动物种属而异,但在大多数哺乳动物中,它位于颞叶背内侧部,侧脑室下角尖端的前上方,背邻豆状核,尾侧联于尾状核,咀侧毗邻前穿质.人脑中,杏仁核是海马回钩的一部分,位于海马脚咀侧末端之前,借侧脑室下脚裂隙状顶端与海马分离.杏仁核可分为许多亚核,亚核的数量(5～22个)虽各家报告不同,但皮层内侧核和基底外侧核是公认的两个最大的亚核.杏仁核的纤维联系十分复杂,其传出径路主要是终纹和腹侧离杏仁核径路.前者在     

神经导航锁孔入路选择性杏仁核海马切除术治疗内侧颞叶癫(癎)(附23例分析)

目的 探讨神经导航下锁孔入路选择性杏仁核海马切除术治疗内侧颢叶癫(癎)的疗效及手术经验.方法 回顾性分析23例药物难治性内侧颞叶癫(癎)的手术经验.均在无框架神经导航指引下,经颢部锁孔开颅,在显微镜下分开一小段颞下沟,切开侧脑室颢角前外侧壁后进入侧脑室,选择性切除杏仁核海马,并将海马旁回和钩回逐步吸除.结果 本组无严重手术并发症发生.术后随访24-57个月,Engel Ⅰ级(发作完全消失)17例(73.9%),Ⅱ级4例(17.4%),Ⅲ级2例(8.7%).结论 神经导航下经锁孔颞下沟入路选择性杏仁核海马切除术是治疗内侧颞叶癫(癎)的有效方法,手术创伤小,可妥善保护语言区和视放射,安全性高.     

导航引导下保留侧脑室完整的颞叶癫痫手术26例体会

目的探讨神经导航下保留侧脑室完整的前颞叶海马、杏仁核切除术治疗颞叶癫痫的效果。方法将26例神经导航下保留侧脑室完整的前颞叶海马切除术后患者的术前Wada试验评估、术后并发症及癫痫控制情况进行分析。结果术后随访时间24～36月,EngelⅠ级22例（85％）,EngelⅡ级3例（11％）,EngelⅢ例（4％）。术后1例（4％）患者出现记忆减退症状,4例患者发生视野缺损。结论同时切除海马、杏仁核的标准前颞叶切除术为外科治疗颞叶癫痫的有效术式,术前Wada试验评估能很好的预测手术对患者记忆功能的影响,保留侧脑室完整的术式可减少视野缺损的发生。     

经锁孔颞下入路选择性杏仁核海马切除术治疗颞叶内侧癫

目的探讨经锁孔颞下入路选择性杏仁核海马切除术治疗颞叶内侧癫的手术方法及疗效。方法回顾性分析29例颞叶内侧癫的病例资料,均在全麻下行后颞锁孔开颅,经梭状回造瘘进入侧脑室颞角,分块切除杏仁核海马及海马旁回等颞叶内侧结构。结果 29例病人术后平均随访43个月,Engel癫疗效分级:Ⅰ级24例,Ⅱ级2例,Ⅲ级2例,Ⅳ级1例。无失语、严重记忆力减退及视野缺损发生。结论选择性杏仁核海马切除术是治疗颞叶内侧癫的有效方法,创伤小,可妥善保护语言区、颞干和视放射。     

经颞下回-侧脑室入路选择性海马杏仁核切除术治疗内侧颞叶癫痫

目的 探讨经颞下回-侧脑室入路选择性海马杏仁核切除术治疗内侧颞叶癫痫的手术方法 、疗效及并发症. 方法 对确诊为药物难治性内侧颞叶癫痫的62例患者,经颞部锁孔开颅,切除中前段颞下回,进入颞角前外侧区,选择性切除海马杏仁核及海马旁回等内侧颞叶结构.结果 62例患者术后随访至少24～80个月,无严重手术并发症;Engel癫痫疗效分级;Ⅰ级45例(72.6%),Ⅱ级12例(19.4%),Ⅲ级5例(8.0%). 结论 经颢下回-侧脑室入路选择性海马杏仁核切除术是治疗内侧颞叶癫痫的有效方法 ,其手术创伤小,可妥善保护语言区和视放射,安全性高.     

Intersubject variability in the anterior extent of the optic radiation assessed by tractography

INTRODUCTION: Temporal lobe resection for epilepsy involves a risk of damaging the anterior part of the optic radiation, Meyer's loop, causing a contralateral upper quadrant visual field defect. This study aims to assess the intersubject variability in the course of Meyer's loop in vivo by diffusion tensor imaging and tractography. METHODS: Seven healthy volunteers and two patients with previous temporal lobe resection were recruited. Diffusion tensor imaging and tractography were used to visualize the optic radiation. The distances from the anterior edge of Meyer's loop to landmarks in the temporal lobe were calculated. RESULTS: In the healthy subjects, the mean distance between the most anterior part of Meyer's loop and the temporal pole was 44 mm (range 34-51 mm). Meyer's loop did not reach the tip of the temporal horn in any subject. A disruption in Meyer's loop could be demonstrated in the patient with quadrantanopia after temporal lobe resection. CONCLUSIONS: Meyer's loop has a considerable variability in its anterior extent. Tractography may be a useful method to visualize Meyer's loop, and assess the risk of a visual field defect, prior to temporal lobe resection.     

Lesions of the optic radiations mimicking lateral geniculate nucleus visual field defects.

Three patients were found to have visual field defects which involved homonymous horizontal sectors of the visual fields, thus mimicking field defects associated with lesions of the lateral geniculate nucleus. Computed tomography provided anatomical evidence that the responsible lesion involved the optic radiations rather than the lateral geniculate nucleus.     

Anatomical connections of viral system with limbic cortex of monkey

The question of anatomical connections between the visual system and the temporo-occipital limbic cortex was investigated in 24 squirrel monkeys (Saimiri sciureus) with the utilization of stains for showing fine degenerating cortical fibers. Lesions of various size were placed in the geniculo-pulvinar complex by electrocoagulation. Electrodes were usually inserted in the Horsley-Clarke frontal plane, but in two cases lesions of the lateral geniculate body were made by an extracerebral approach. With a lesion well confined to the ventrolateral part of the lateral geniculate body, heavy degeneration appeared in the inferior longitudinal fasciculus and continued into its ventromedial extension designated as band 3 in the core of the posterior hippocampal gyrus. Some degenerating fibers could be traced from band 3 into the cortex of this gyrus, as well as into adjoining cortical areas in the fusiform and lingual gyri. Sparse degeneration in the postsplenial cortex could not be excluded as arising from the lesion made by an electrode in approaching the lateral geniculate body in the frontal plane. Degeneration in band 3 did not extend as far forward as the entorhinal cortex in the anterior hippocampal gyrus. In two animals with small rostral lesions of the lateral geniculate body made by the extracerebral approach, some degeneration also extended into band 3, supporting other control observations that such degeneration is not dependent on the destruction of tissue made by an electrode in approaching the lateral geniculate body in the frontal plane. When a lesion involved the inferior pulvinar as well as the lateral geniculate body, heavier degeneration appeared in the posterior hippocampal, fusiform, and lingual cortex. With a large lesion of the inferior pulvinar, a band of degeneration appeared ventrolateral to the optic radiations and was traced into these same cortical areas. The anatomical results are discussed in the light of recent microelectrode findings of photically responsive units in the cortex of posterior hippocampal gyrus and adjoining cortical areas. The combined evidence suggests an explanation for the temporal detour made by that part of the optic radiations commonly referred to as Meyer's temporal loop.     

Visual field defects in vascular lesions of the lateral geniculate body.

Corresponding retinal nerve fibres begin their path in the eyes and end in a single visual cortical cell. Because of this arrangement, lesions in the anterior visual pathway produce incongruent visual field defects and in the posterior pathway congruent field defects. The lateral geniculate body is on the anterior third of the visual pathway. A lesion of this nucleus produces moderately to completely congruent visual field defects. Five patients with ischaemic lesions of the lateral geniculate body are reported. Two patients had a wedge-shaped homonymous hemianopia, two other cases had congruent superior homonymous quadratic defects and the fifth a quadruple sector defect. The lateral geniculate body has a dual blood supply from the anterior choroidal artery (branch from internal carotid artery) and from the lateral choroidal artery (branch from the posterior cerebral artery). A schematic diagram has been devised which shows that a knowledge of the visual field disrupted can identify the arterial system involved.     

Diffusion tensor imaging tractography of the optic radiation for epilepsy surgical planning: a comparison of two methods

The optic radiation is a key white matter structure at risk during epilepsy surgery involving the temporal, parietal or occipital lobes. It shows considerable anatomical variability, cannot be delineated on clinical MRI sequences and damage may cause a disabling visual field deficit. Diffusion tensor imaging tractography allows non-invasive mapping of this pathway. Numerous methods have been published but direct comparison is difficult as patient, acquisition and analysis parameters differ. Two methods for delineating the optic radiation were applied to 6 healthy controls and 4 patients with epileptogenic lesions near the optic radiation. By comparing methods with the same datasets, many of the parameters could be controlled. The first method was previously developed to accurately identify Meyer's loop for planning anterior temporal lobe resection. The second aimed to address limitations of this method by using a more automated technique to reduce operator time and to depict the entire optic radiation. Whilst the core of the tract was common to both methods, there was significant variability between the methods. Method 1 gave a more consistent depiction of Meyer's loop with fewer spurious tracts. Method 2 gave a better depiction of the entire optic radiation, particularly in more posterior portions, but did not identify Meyer's loop in one patient. These results show that whilst tractography is a promising technique, there is significant variability depending on the method chosen even when the majority of parameters are fixed. Different methods may need to be chosen for surgical planning depending on the individual clinical situation.     

Visual field defects after temporal lobe resection: a prospective quantitative analysis.

OBJECTIVE: To evaluate and quantify prospectively visual field changes in patients undergoing temporal lobe resections for intractable epilepsy. BACKGROUND: Visual field abnormalities occur after temporal lobe resections for epilepsy; however, we have not encountered published reports using automated static visual field analysis. METHODS: Humphrey visual fields (program 30-2) were obtained before and after partial temporal lobe resection in 32 consecutive patients with intractable epilepsy. A quantitative point-by-point analysis was made in the affected superior quadrant, and the defects were averaged for the whole patient group. RESULTS: Thirty-one patients developed a visual field defect, but none was aware of the defect. The points nearest fixation were relatively spared. The defects were greatest in the sector closest to the vertical meridian in the eye ipsilateral to the resection. The ipsilateral and contralateral mean field defects also differed in both topography and depth. A significant correlation was found between the extent of lateral temporal lobe resection and the degree of the defect in the contralateral eye. CONCLUSIONS: There are differences in the shape and depth of the ipsilateral and the contralateral field defects not previously reported. These findings demonstrate that certain fibers from the ipsilateral eye travel more anteriorly and laterally in Meyer's loop, and support the hypothesis that visual field defects due to anterior retrogeniculate lesions are relatively incongruous because of anatomic differences in the afferent pathways. Automated perimetry is a sensitive method of evaluating and quantifying visual field defects.     

Symptomatic retrochiasmal lesions in multiple sclerosis: clinical features, visual evoked potentials, and magnetic resonance imaging.

We have studied 18 patients with relapsing-remitting multiple sclerosis (MS) who had symptomatic visual field defects due to retrochiasmal lesions. In 17, the lesion responsible was identified by magnetic resonance imaging (MRI), computed x-ray tomography (CT), or both. The lesion responsible involved the posterior optic radiations in eight cases, the optic tract and lateral geniculate nucleus in six, and the posterior limb of the internal capsule in three. The prognosis for recovery of the field defect was good; complete recovery occurred in 14 patients, and only two showed no recovery at all. The striking characteristic of the lesions was that most were unusually large; indeed, many were detectable on CT as well as MRI. Half-field asymmetries of either amplitude or latency of the visual evoked potentials (VEPs), consistent with a postchiasmal lesion, were present in only five out of 13 patients acutely. In only three of these did the abnormality persist at follow-up. We conclude that only large postchiasmal lesions are likely to cause symptomatic homonymous field defects in MS, usually characterized by rapid recovery. Hemifield VEPs have a low sensitivity for the detection of postchiasmal as compared with prechiasmal abnormalities.     

Topographic organization of the projections from cortical areas 17, 18, and 19 onto the thalamus,pretectum and superior colliculus in the cat

The distribution of cortical projections from areas 17, 18, and 19 to the lateral thalamus, pretectum, and superior colliculus was investigated with the autoradiographic tracing method. Cortical areas 17, 18 and 19 were demonstrated to project retinotopically and in register upon the dorsal lateral geniculate nucleus, medial interlaminar nucleus, lateral zone of the lateral posterior complex, nucleus of the optic tract and superior colliculus. Area 19 was shown to project retinotopically upon the pulvinar nucleus. Clear retinotopic organization was not demonstrable in the projections of areas 17, 18 and 19 to the reticular complex of the thalamus and ventral lateral geniculate nucleus, or in the projection of area 19 to the anterior pretectal nucleus. The cortical projections were employed to define the retinotopic organization of the nucleus of the optic tract, pulvinar nucleus, and lateral zone of the lateral posterior complex. The cortical projections show the vertical meridian to be represented caudally, with the lower visual field represented laterally, and the upper visual field medially, within the nucleus of the optic tract. The projections of area 19 to the pulvinar nucleus demonstrate the lower visual field to be represented rostrally and the upper visual field caudally in this nucleus; the vertical meridian to be represented at the lateral border and the visual field periphery to be represented at the medial border of the pulvinar nucleus. Cortical projections to the lateral zone of the lateral posterior complex demonstrate the lower visual field to be represented rostrally and the upper visual field caudally; the vertical meridian to be represented at the medial limit and the visual field periphery at the lateral border of the termination zones. On the basis of the experimental findings, a new terminology is introduced for the feline lateral posterior complex. Divisions are proposed which correspond to zones with demonstrably distinct afferent input. The pulvinar nucleus is defined by the distribution of projections from area 19. Three flanking divisions are defined within the lateral posterior complex; a lateral division recipient of projections from area 17, 18 and 19, an interjacent division recipient of projections of the superficial layers of the superior colliculus, and a medial division flanking the tectorecipient zone medially.     

Diffusion tensor anisotropy in adolescents and adults

We acquired diffusion tensor images on 33 normal adults aged 22-64 and 15 adolescents aged 14-21. We assessed relative anisotropy in stereotaxically located regions of interest in the internal capsule, corpus callosum, anterior thalamic radiations, frontal anterior fasciculus, fronto-occipital fasciculus, temporal lobe white matter, cingulum bundle, frontal inferior longitudinal fasciculus, frontal superior longitudinal fasciculus, and optic radiations. All of these structures except the optic radiations, corpus callosum, and frontal inferior longitudinal fasciculus exhibited differences in anisotropy between adolescents and adults. Areas with anisotropy increasing with age included the anterior limb of the internal capsule, superior levels of the frontal superior longitudinal fasciculus and the inferior portion of the temporal white matter. Areas with anisotropy decreasing with age included the posterior limb of the internal capsule, anterior thalamic radiations, fronto-occipital fasciculus, anterior portion of the frontal anterior fasciculus, inferior portion of the frontal superior longitudinal fasciculus, cingulum bundle and superior portion of the temporal axis. Sex differences were found in the majority of areas but were most marked in the cingulum bundle and internal capsule. These results suggest continuing white matter development between adolescence and adulthood.     

MR tractography predicts visual field defects following temporal lobe resection

A superior homonymous quadrantanopia is a well recognized complication of anterior temporal lobe resection and occurs because of disruption of the Meyer loop, the anterior part of the optic radiation. The authors used diffusion tensor imaging tractography to visualize the optic radiation before and after surgery, demonstrating the disruption of Meyer loop in a patient who developed a quadrantanopia. Preoperative imaging of the optic radiation will be useful in predicting visual field defects following temporal lobe resection.