Ulm Arthur J, Russo Antonino, Albanese Erminia, Tanriover Necmettin, Martins Carolina, Mericle Robert M, Pincus David, Rhoton Albert L
Georgia Neurosurgical Institute, Mercer University School of Medicine, Macon, Georgia 31201, USA.
J Neurosurg. 2009 Sep;111(3):600-9. doi: 10.3171/2008.7.JNS08124.
The aim of this study was to determine the anatomical limitations of the transcallosal transchoroidal approach to the third ventricle.
Twenty-six formalin-fixed specimens were studied. Sagittal dissections were used to determine the anatomical relationships of the foramen of Monro, the angle of approach to landmarks, and placement of a callosotomy. Lateral ventricular dissections were performed to quantitate the forniceal anatomy.
The foramen of Monro was found 1.07+/-0.11 cm superior and slightly anterior to the mammillary bodies, 1.48+/-0.16 cm posterosuperior to the optic recess, and 2.26+/-0.16 cm anterosuperior to the aqueduct. Relative to the genu, a callosal incision 2.64+/-0.53 cm long and angled 37+/-4.3 degrees anterior was needed to access the aqueduct, and an incision 4.92+/-0.71 cm long and angled 49+/-7.4 degrees posterior was needed to access the optic recess. The fornix progressively widened within the lateral ventricle, from 1.25+/-0.63 mm at the foramen of Monro to >7 mm at 2 cm behind the foramen. Three zones of exposure were identified, requiring unique craniotomies, callosotomies, and angles of approach. The major limiting factors in the approach included the columns of the fornix anteriorly, the width of the fornix posteriorly, and the draining veins of the parietal cortex. The choroidal fissure opening was limited to 1.5 cm posterior to the foramen of Monro; this limited opening created an aperture effect that required an anterior-to-posterior angle, an anterior craniotomy, and an anteriorly placed callosotomy to access the posterior landmarks. In contrast, a posterior-to-anterior angle, posteriorly placed craniotomy, and posteriorly placed callosotomy were required to access anterior landmarks.
The transcallosal transchoroidal approach was ideally suited to access the foramen of Monro and the middle and posterior thirds of the third ventricle. Exposure of the anterior third ventricle was limited by the columns of the fornix and by the presence of parietal cortical draining veins.
本研究旨在确定经胼胝体经脉络膜入路至第三脑室的解剖学限制。
对26个福尔马林固定标本进行研究。采用矢状面解剖来确定室间孔的解剖关系、入路角度与标志点的关系以及胼胝体切开术的位置。进行侧脑室解剖以量化穹窿的解剖结构。
发现室间孔位于乳头体上方1.07±0.11 cm且略偏前，视隐窝后上方1.48±0.16 cm，导水管前上方2.26±0.16 cm。相对于胼胝体膝部，需要一个长2.64±0.53 cm且向前成角37±4.3度的胼胝体切口来进入导水管，需要一个长4.92±0.71 cm且向后成角49±7.4度的切口来进入视隐窝。穹窿在侧脑室内逐渐变宽，从室间孔处的1.25±0.63 mm增至室间孔后方2 cm处的>7 mm。确定了三个暴露区域，需要独特的开颅术、胼胝体切开术和入路角度。该入路的主要限制因素包括前方的穹窿柱、后方的穹窿宽度以及顶叶皮质的引流静脉。脉络膜裂开口限制在室间孔后方1.5 cm处；这种有限的开口产生了一种孔径效应，需要从前向后的角度、前部开颅术和靠前放置的胼胝体切开术来进入后方标志点。相比之下，进入前方标志点则需要从后向前的角度、靠后放置的开颅术和靠后放置的胼胝体切开术。
经胼胝体经脉络膜入路非常适合进入室间孔以及第三脑室的中后段。第三脑室前段的暴露受到穹窿柱和顶叶皮质引流静脉的限制。
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