The white matter tracts of the cerebrum in ventricular surgery and hydrocephalus

Abstract

S urgical approaches to the lateral ventricle always require passage through one and often multiple fiber tracts to reach their target. These approaches remain a challenge because of the deep location and variable shape and size of the ventricles, their covering mantle of tracts, and relationships to important neural structures such as the thalamus and internal capsule. 55,75,84 In addition, a number of tracts course in the walls of the ventricle where they are separated from the cerebrospinal fluid by only a thin layer of ependyma and would likely be exposed to the greatest possibility of damage by hydrocephalus.84,124 Recent studies have focused on the relationships of the fiber tracts to eloquent cortical areas and avoiding the optic radiations in approaches to the lateral ventricle. 16,41,48,59,63,75,89,92,94,125 The aim of the present study was to explore the relationships of the tracts to the lateral ventricles and the various surgical approaches to the ventricles and to examine the anatomy and syndromes related to ventricular enlargement. MethodsForty adult human formalin-fixed cadaveric hemispheres (20 brains) were examined under magnification that ranged from ×6 to ×40. The dura, pia, arachnoid, and surface vessels were gently removed. All specimens were frozen in water for at least 2 weeks at -16°C, as described by Klingler, to separate the tracts and facilitate dissection. 51 After freezing, the specimens were thawed and rinsed of formalin under tap water for at least 1 hour. Prior OBJECTIVEThe relationship of the white matter tracts to the lateral ventricles is important when planning surgical approaches to the ventricles and in understanding the symptoms of hydrocephalus. The authors' aim was to explore the relationship of the white matter tracts of the cerebrum to the lateral ventricles using fiber dissection technique and MR tractography and to discuss these findings in relation to approaches to ventricular lesions. METHODS Forty adult human formalin-fixed cadaveric hemispheres (20 brains) and 3 whole heads were examined using fiber dissection technique. The dissections were performed from lateral to medial, medial to lateral, superior to inferior, and inferior to superior. MR tractography showing the lateral ventricles aided in the understanding of the 3D relationships of the white matter tracts with the lateral ventricles. RESULTS The relationship between the lateral ventricles and the superior longitudinal I, II, and III, arcuate, vertical occipital, middle longitudinal, inferior longitudinal, inferior frontooccipital, uncinate, sledge runner, and lingular amygdaloidal fasciculi; and the anterior commissure fibers, optic radiations, internal capsule, corona radiata, thalamic radiations, cingulum, corpus callosum, fornix, caudate nucleus, thalamus, stria terminalis, and stria medullaris thalami were defined anatomically and radiologically. These fibers and structures have a consistent relationship to the lateral ventricles. CONCLUSIONS Knowledge of the relationship of the white matter tracts o...

Microsurgical anatomy of the subthalamic nucleus: correlating fiber dissection results with 3-T magnetic resonance imaging using neuronavigation

“…Neurophysiological confirmation is generally accomplished with microelectrode recording and macrostimulation techniques. 9,18 If the ideal target can be reached with effective anatomical targeting, then the time required for neurophysiological confirmation will be strikingly shortened. 57 Regardless of the method used, understanding the 3D anatomical relations of the STN region is mandatory for optimal surgical results-and for minimizing unwelcome side effects.…”

“…After fixation, all specimens were frozen in water for at least 2 weeks at -16°C to facilitate dissection, in accordance with the Klingler method. 18,29 The arteries and veins of the whole heads were injected with blue or red silicone rubber (Dow Corning Corp.), RTV catalyst (Dow Corning Corp.), and Thinner 200 (Dow Corning Corp.). The dura mater, arachnoid membrane, and surface vessels were removed carefully under the microscope (Carl Zeiss AG) with 6×-40× magnification after at least 1 hour of thawing under tap water.…”

Defining the relationship of the optic radiation to the roof and floor of the ventricular atrium: a focused microanatomical study

“…Although previous laboratory studies have explored the microsurgical anatomy of the visual pathways and investigated their possible implications in the most commonly used approaches to the ventricular compartmen ts, 5,8,9,12,13,15,19,27,29,33,36,37,[42][43][44] evidence regarding the specific relationship of the optic radiations to the floor and roof of the ventricular trigone is ambiguous. Although some authors topographically related the atrial roof and floor to the fibers of the posterior and/or central optic bundle and anterior optic bundle, respectively, others did not define the precise anatomical correlation.…”

“…Although some authors topographically related the atrial roof and floor to the fibers of the posterior and/or central optic bundle and anterior optic bundle, respectively, others did not define the precise anatomical correlation. 5,9,15,27,30,36,37,42 In that respect, and by reviewing the relevant literature, we have listed in Table 1 the most recent and detailed papers on the optic pathway fiber tract architecture along with the authors' relevant comments on the relationship of the optic tract to the atrial floor and roof. In this table, it is evident * With regard to the atrial floor, the only study that defined the anatomical correlation, stating that the optic radiations and, more specifically, the anterior optic bundle, courses on the lateral part of the atrial floor is that by Güngör et al (2017).…”

“…During our study, particular emphasis was placed on the correlative topography of the intraparietal and collateral sulci to the roof and floor of the ventricular atrium, respectively, because these sulci have been used as surgical corridors for treating atrial lesions because of their short and direct access to the ventricle. 1,9,10,12,13,15,[17][18][19]29,41,50 In this context, the intraparietal sulcus, when it has the appropriate morphological characteristics (i.e., a straight, continuous sulcal segment of at least 3 cm for microsurgical dissection), offers a safe and effective trajectory to the atrium that avoids injury to the optic pathway. 12,15,[17][18][19]21,41 However, there is a tight relation between the plane of subcortical dissection achieved and the location of the SLF, particularly at the most anterior part of the sulcus.…”