Stereotactic Localization of the Monro Foramen and the Safest Stereotactic Interforniceal Approach to the Third Ventricle: A Neuroanatomical Study

Abstract

Background and Objective To localize the human foramen of Monro stereotactically, to define the anatomical parameters of the safest stereotactic transcallosal transseptal interforniceal approach to the third ventricle, and to show how neurosurgeons could use them in preoperative planning.

Material and Methods Our material consisted of 44 formalin-fixated human cerebral hemispheres. We found the location of the anterior (AC) and posterior commissure at the internal hemispheric surface. The posterosuperior border of the AC (point A) was our stereotactic reference point with coordinates (X, Y, Z) = (0, 0, 0). We found the Monro foramen location and measured the stereotactic coordinates of its anterior inferior border (point B). The safest trajectory to the third ventricle has to pass as far as possible from points A and B so as not to traumatize the choroid plexus of the Monro foramina or the AC. The midpoint of the AB distance (point M) is the stereotactic point that provides this safest trajectory. We also measured AB length and point M stereotactic coordinates.

Results Mean stereotactic coordinates of the (midline projection of the) point B were (X, Y, Z) = (0, −0.6, 2.4). Point B was located averagely 3.2 mm far from point A. Mean stereotactic coordinates of the point M, a necessary component of the trajectory of the safest stereotactic interforniceal approach to the third ventricle, were (X, Y, Z) = (0, −0.3, 1.2). Point M was located 1.6 mm far from point A.

Conclusions The present study shows how neurosurgeons can localize and use crucial anatomical landmarks, namely the AC and foramen of Monro, to approach the third ventricle safely via a stereotactic interforniceal technique. This can be achieved during preoperative planning with simple identification of stereotactic points A, B, and M on preoperative median sagittal magnetic resonance images.

Keywords

foramen of Monro - interforniceal approach - stereotactic coordinates - third ventricle

• References

• 1 Paleologos TS, Wadley JP, Kitchen ND, Thomas DG. Interactive image-guided transcallosal microsurgery for anterior third ventricular cysts. Minim Invasive Neurosurg 2001; 44 (3) 157-162
• 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 (2) 309-317 ; discussion 317–319
• 3 Villani R, Papagno C, Tomei G, Grimoldi N, Spagnoli D, Bello L. Transcallosal approach to tumors of the third ventricle. Surgical results and neuropsychological evaluation. J Neurosurg Sci 1997; 41 (1) 41-50
• 4 Kumar V, Behari S, Kumar Singh R, Jain M, Jaiswal AK, Jain VK. Pediatric colloid cysts of the third ventricle: management considerations. Acta Neurochir (Wien) 2010; 152 (3) 451-461
• 5 Wen HT, Rhoton Jr AL, de Oliveira E. Transchoroidal approach to the third ventricle: an anatomic study of the choroidal fissure and its clinical application. Neurosurgery 1998; 42 (6) 1205-1217 ; discussion 1217–1219
• 6 Ozer MA, Kayalioglu G, Erturk M. Topographic anatomy of the fornix as a guide for the transcallosal-interforniceal approach with a special emphasis on sex differences. Neurol Med Chir (Tokyo) 2005; 45 (12) 607-612 ; discussion 612–613
• 7 Winkler PA, Weis S, Büttner A, Raabe A, Amiridze N, Reulen HJ. The transcallosal interforniceal approach to the third ventricle: anatomic and microsurgical aspects. Neurosurgery 1997; 40 (5) 973-981 ; discussion 981–982
• 8 Siwanuwatn R, Deshmukh P, Feiz-Erfan I , et al. Microsurgical anatomy of the transcallosal anterior interforniceal approach to the third ventricle. Neurosurgery 2005; 56 (2, Suppl): 390-396 , discussion 390–396
• 9 Erturk M, Kayalioglu G, Ozer MA, Ozgur T. Morphometry of the anterior third ventricle region as a guide for the transcallosal-interforniceal approach. Neurol Med Chir (Tokyo) 2004; 44 (6) 288-292 ; discussion 292–293
• 10 Vialogo JG. Endoscopic transepto-interforniceal approach to colloid cysts: case report [in Portuguese]. Arq Neuropsiquiatr 2000; 58 (3B): 939-946
• 11 Zohdi A, El Kheshin S. Endoscopic approach to colloid cysts. Minim Invasive Neurosurg 2006; 49 (5) 263-268
• 12 Rosenfeld JV. The evolution of treatment for hypothalamic hamartoma: a personal odyssey. Neurosurg Focus 2011; 30 (2) E1
• 13 Polkey CE. Resective surgery for hypothalamic hamartoma. Epileptic Disord 2003; 5 (4) 281-286
• 14 Harvey AS, Freeman JL, Berkovic SF, Rosenfeld JV. Transcallosal resection of hypothalamic hamartomas in patients with intractable epilepsy. Epileptic Disord 2003; 5 (4) 257-265
• 15 Rosenfeld JV, Freeman JL, Harvey AS. Operative technique: the anterior transcallosal transseptal interforniceal approach to the third ventricle and resection of hypothalamic hamartomas. J Clin Neurosci 2004; 11 (7) 738-744
• 16 Winkler PA, Ilmberger J, Krishnan KG, Reulen HJ. Transcallosal interforniceal-transforaminal approach for removing lesions occupying the third ventricular space: clinical and neuropsychological results. Neurosurgery 2000; 46 (4) 879-888 ; discussion 888–890
• 17 Zhang YQ, Ma ZY, Wu ZB, Luo SQ, Wang ZC. Radical resection of 202 pediatric craniopharyngiomas with special reference to the surgical approaches and hypothalamic protection. Pediatr Neurosurg 2008; 44 (6) 435-443
• 18 Geng SM, Zhang JT, Zhang LW, Wu Z, Wang ZC. Optimal microsurgical treatment of dorsum sellae meningioma. Chin Med J (Engl) 2009; 122 (16) 1857-1861
• 19 Gong J, Ma ZY, Zhang YQ, Jia G, Xie J. Transcallosal interforniceal approach for removing the medial type of thalamic gliomas [in Chinese]. Zhonghua Yi Xue Za Zhi 2005; 85 (20) 1388-1391
• 20 Abe T, Sugishita M, Yatsuzuka S , et al. Transcallosal interforniceal approach for a posteriorly projecting high basilar bifurcation aneurysm. Case report. J Neurosurg 1993; 78 (6) 970-973
• 21 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 (5) 544-547 ; discussion 547
• 22 Souweidane MM, Hoffman CE, Schwartz TH. Transcavum interforniceal endoscopic surgery of the third ventricle. J Neurosurg Pediatr 2008; 2 (4) 231-236
• 23 Asgari S, Engelhorn T, Brondics A, Sandalcioglu IE, Stolke D. Transcortical or transcallosal approach to ventricle-associated lesions: a clinical study on the prognostic role of surgical approach. Neurosurg Rev 2003; 26 (3) 192-197