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 »  Abstract
 »  Introduction
 »  Case Report
 »  Discussion
 »  Acknowledgment
 »  References
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Table of Contents    
CASE REPORT
Year : 2010  |  Volume : 58  |  Issue : 6  |  Page : 942-944

Cavum septum pellucidum: A feasible route to third ventricle


1 Department of Neurological Surgery, Tri-Service General Hospital, Taipei, China
2 Department of Neurological Surgery, Taipei Medical University Hospital, Taiwan, China

Date of Acceptance27-Aug-2010
Date of Web Publication10-Dec-2010

Correspondence Address:
Jiann-Her Lin
No.252, Wuxing St., Xinyi Dist., Taipei City 110, Taiwan
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.73754

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 » Abstract 

Tumors located within the third ventricle have some potential limitations during surgical approach. Generally speaking, it is impossible to reach the third ventricle without incision of any neural structure. We report a patient with choroid glioma in the anterior part of the third ventricle, and coincident cavum septum pellucidum (CSP) in whom we could remove the tumor gross totally without damaging any neurovascular structures. The tumor expanded the space between the rostrum of the corpus callosum and the column of the fornix and lifted up the floor of CSP. The transcavum-septum-pellucidum approach anterior to foramen of Monro was chosen to remove the anterior third ventricle tumor. We propose that the tumor had likely expanded within the above-mentioned space and elevated the floor of CSP thus increasing the anteroposterior diameter of the floor providing a feasible avenue to third ventricle making it feasible to pass through the enlarged space safely. Overall, cavum septum pellucidum provided a feasible route to approach the anterior third ventricle directly.


Keywords: Anterior third ventricle tumor, cavum septum pellucidum, transcallosal approach


How to cite this article:
Tseng KY, Ma HI, Hueng DY, Lin JH. Cavum septum pellucidum: A feasible route to third ventricle. Neurol India 2010;58:942-4

How to cite this URL:
Tseng KY, Ma HI, Hueng DY, Lin JH. Cavum septum pellucidum: A feasible route to third ventricle. Neurol India [serial online] 2010 [cited 2019 Dec 15];58:942-4. Available from: http://www.neurologyindia.com/text.asp?2010/58/6/942/73754



 » Introduction Top


The third ventricle is one of the most surgically inaccessible areas in the brain. It is impossible to reach its cavity without incising any neural structure. [1] The interhemispheric-transcollosal approach is commonly used to reach the lateral ventricle, where one could choose transforminal, transchoroidal fissure; or interfornical exposure to reach the third ventricle. [2] However, these approaches may result in damage to the fornices, internal cerebral veins, posterior medial choroidal arteries, and parietal cortical draining veins. [3],[4],[5] Herein, we report a patient with a tumor in the anterior third ventricle and a coincident cavum septum pellucidum (CSP). The transcavum-septum-pellucidum approach anterior to foramen of Monro was utilized to remove the tumor without damaging the critical structures.


 » Case Report Top


A 50-year-old man presented with impaired memory and depressed mood of two years duration. Contrast brain magnetic resonance imaging (MRI) showed a contrast-enhancing mass measuring 3.3 Χ 3.5 cm, located in the anterior part of the third ventricle and blocking both the foramen of Monro, causing dilatation of both the lateral ventricles. It also showed a coincident cavum septum pellucidum bounded anteriorly by the genu of the corpus callosum and posteriorly by the column of the fornix. The floor of cavum was lying right over the tumor mass [Figure 1]. During surgery, the corpus callosum was exposed, and a 1.5-cm oval callosotomy was made. Using retractor to advance the cavity further toward the tumor the boundaries of the cavity could be identified: anteriorly the genu, on either side by septal leaves which extended posteriorly to fuse as a blind end. With the guidance of the navigator system, the cavity was identified as the septal pellucidi, and the floor was found to be lying right over the tumor mass. Anatomically, the CSP has the following boundaries: anteriorly, the genu of the corpus callosum; posteriorly, the columns of fornix; inferiorly, the rostrum of corpus callosum and the anterior commissure. Therefore, it was possible to stay within the CSP without opening the septal leaves and directly open its floor to access the tumor mass between the anterior commissure and column of the fornix. Opening the floor uncovered the tumor mass, which appeared gray in color and firm in consistency with a clear margin between the surrounding third ventricle walls except the anterior wall [Figure 2]. The tumor seemed to originate from the anterior third ventricle wall. During the removal of the tumor, small cottonoids were placed between the tumor wall and the third ventricle for the dissection of the plane. The attachment to the lamina terminalis was severed using a micro-scissors and a micro-dissector. After the tumor was completely removed, one could visualize the floor of the third ventricle anterior to the orifice of aqueduct of the sylvius posteriorly. Postoperatively patient had transient diabetes insipidus. He had gradual improvement in his memory. The pathology of the tumor revealed choroid glioma. Postoperative MRI demonstrated the route of approach to the tumor, from the interhemispheric fissure through the transcavum septum pellucidum, and confirmed the total excision of the tumor [Figure 3].
Figure 1: Magnetic resonance imaging in sagittal (a), coronal (b) and axial (c) planes showed the relationship between CSP and the tumor and the boundaries of CSP: anteriorly, the genu of the corpus callosum; posteriorly, the column of the fornix. The arrow indicates transcavum-septum-pellucidum approach

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Figure 2: (a) View of CSP before opening of the floor. The lateral boundaries were limited by two septal leaves. (b) The floor of CSP was lying right over the tumor mass

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Figure 3: Postoperative gadolinium-enhanced T1-weighted images in coronal (a) and sagittal (b) planes demonstrate the route of approach to the third ventricle from the transcavum septum pellucidum and confirm complete removal of the tumor

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 » Discussion Top


The anterior transcallosal approach leads surgeons to the lateral ventricle, where several access routes to the third ventricle are available: the foramen of Monro pathway, the interfornical pathway and the transchoroidal approach. [6] The transforaminal approach requires enlargement of the foramen and results in sectioning of the fornix or damage to the anterior nuclei of the thalamus. [7] Moreover, removal of the posterior foraminal tissue has the risk of causing uncontrollable venous bleeding from the internal cerebral vein. [8] The interfornical approach usually leads to damage to the fornices, the internal cerebral veins and the posterior medial choroidal arteries, especially causing bilateral fornical injury in patients with CSP or cavum vergae (CV). [1] The approach via the transchoroidal plane has limitations of exposure of the anterior third ventricle because of the columns of the fornix and the presence of parietal cortical draining veins. [5]

This patient had anatomic variation at the fornix-septum pellucidum complex and the cavum septum pellucidum. The boundaries were: anteriorly, the genu of the corpus callosum; superiorly, the body of the corpus callosum; posteriorly, the anterior limbs and columns of the fornix; inferiorly, the rostrum of the corpus callosum and the anterior commissure; laterally, the two leaves of the septum pellucidum. [9] Staying within the CSP and opening the floor indicated the availability of a potential avenue into the third ventricle. However, there have been previous reports of confusion usually arising while entering the CSP, due to the absence of familiar ventricular landmarks such as the foramen of Monro, the thalamostriate vein and the choroid plexus in the lateral ventricle. [10] In this patient, the tumor located in the anterosuperior third ventricle lifted up the floor of CSP and obstructed the foramen of Monro. Furthermore, it expanded the space between the column of the fornix and the rostrum of the corpus callosum. According to Rhoton, [11] the diameter of the space between the anterior commissure and the column of fornix normally ranges between 1.0 and 3.5 mm. Therefore, we propose that the tumor had likely expanded within this space and elevated the floor of CSP. Hence the anteroposterior diameter of the floor was increased by the tumor, which then provided a feasible avenue to third ventricle, making it feasible to pass through the enlarged space anterior to fornix, the internal cerebral vein and the posterior medial choroidal artery. Furthermore, it provided us with a technique to approach the anterior third ventricle directly [Figure 4]. After the tumor was removed, the entire floor of the third ventricle could be easily visualized using optic recess anterior to the orifice of the aqueduct of sylvius. To the best of our knowledge, in selected cases with a coincident CSP, the transcallosal transcavum-septum-pellucidum approach anterior to the foramen of Monro has never been reported in the literature; however, it may be an appropriate solution for the treatment of the anterior third ventricle tumor.
Figure 4: The diagram demonstrates the anterior third of the tumor (purple) expanding the space between the column of fornix (green) and rostrum of corpus callosum (yellow), allowing neurosurgeons to pass through the CSP (blue) - bounded anteriorly by genu of corpus callosum (yellow) and posteriorly by column of fornix (green) - to remove this tumor

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 » Acknowledgment Top


We thank Ryan Lee for English-language editing. This study was supported by grants TSGH-C99-072, TSGH-C99-073, TSGH-C99-074 and TSGH-C99-149 from the Tri-Service General Hospital, Taipei, Taiwan.

 
 » References Top

1.Timurkaynak E, Izci Y, Acar F. Transcavum septum pellucidum interforniceal approach for the colloid cyst of the third ventricle Operative nuance. Surg Neurol 2006;66:544-7.  Back to cited text no. 1
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2.Winkler PA, Weis S, Wenger E, Herzog C, Dahl A, Reulen HJ. Transcallosal approach to the third ventricle: normative morphometric data based on magnetic resonance imaging scans, with special reference to the fornix and forniceal insertion. Neurosurgery 1999;45:309-17.  Back to cited text no. 2
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3.Carmel PW. Tumours of the third ventricle. Acta Neurochir (Wien) 1985;75:136-46.  Back to cited text no. 3
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4.Tsutsumi K, Asano T, Shigeno T, Matsui T. Anterior transcallosal approach for the mass lesions in and around the third ventricle: With particular reference to the method of enlarging the foramen of Monro. No Shinkei Geka 1995;23:137-44.  Back to cited text no. 4
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5.Ulm AJ, Russo A, Albanese E, Tanriover N, Martins C, Mericle RM, et al. Limitations of the transcallosal transchoroidal approach to the third ventricle. J Neurosurg 2009;111:600-9.  Back to cited text no. 5
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6.Rhoton AL Jr, Yamamoto I, Peace DA. Microsurgery of the third ventricle: Part 2. Operative approaches. Neurosurgery 1981;8:357-73.  Back to cited text no. 6
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7.Shucart WA, Stein BM. Transcallosal approach to the anterior ventricular system. Neurosurgery 1978;3:339-43.  Back to cited text no. 7
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8.Little JR, MacCarty CS. Colloid cysts of the third ventricle. J Neurosurg 1974;40:230-5.  Back to cited text no. 8
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9.Born CM, Meisenzahl EM, Frodl T, Pfluger T, Reiser M, Moller HJ, et al. The septum pellucidum and its variants: An MRI study. Eur Arch Psychiatry Clin Neurosci 2004;254:295-302.  Back to cited text no. 9
    
10.Yamamoto I, Rhoton AL Jr, Peace DA. Microsurgery of the third ventricle: Part I. Microsurgical anatomy. Neurosurgery 1981;8:334-56.  Back to cited text no. 10
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11.Rhoton AL Jr. The lateral and third ventricles. Neurosurgery 2002;51:S207-71.  Back to cited text no. 11
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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