The precuneal interhemispheric, trans-tentorial corridor to the pineal region and brainstem, surgical anatomy, and case illustration

Abstract

Background: The pineal region and dorsal midbrain are among the most challenging surgical targets. To approach lesions in this region that harbor a superior to inferior long axis, we describe the basic steps of the precuneal, interhemispheric, trans-tentorial approach and illustrate anatomical landmarks of this established, but not so popular, surgical trajectory.Method: To study the anatomical landmarks and safety of this approach, the neurovascular anatomy was studied on 22 sides of 11 formalin-fixed latex-injected anatomical specimens. A step-by-step dissection of the precuneal interhemispheric trans-tentorial approach and study of the key anatomical landmarks was performed. An illustrative clinical case of a pontomesencephalic cavernous malformation (CM) resected through this approach is also detailed.Results: The mean distance from the transverse sinus to the most posterior cortical vein draining into the superior sagittal sinus was 6.4 cm. The mean distance from the calcarine sulcus to the most posterior cortical vein was 5.3 cm. Key steps of the dissection are as follows: craniotomy exposing the posterior aspect of the superior sagittal sinus (SSS), durotomy and gentle retraction of the SSS edge, dissection of the interhemispheric fissure, linear incision of the tentorium that extends anteriorly to the incisura and lateral reflection of the tentorium, and arachnoidal dissection and exposure of the cerebellomesencephalic fissure. Conclusion:The precuneal, interhemispheric, trans-tentorial approach affords excellent access to the falcotentorial junction, splenium, pineal region, quadrigeminal cistern, and dorsal pons once the cerebellomesencephalic fissure has been dissected.

Comparison Between the Supracerebellar Infratentorial and Precuneal Interhemispheric, Transtentorial Approaches to the Cerebellomesencephalic Fissure: An Anatomoradiological Study and Illustrative Cases

“…The tentorial flap was retracted laterally with sutures, and arachnoid overlying the quadrigeminal cistern was fenestrated (Figure 1). 2,3 The SCIT was performed with the specimen in a simulated upright sitting position. A linear skin incision was made in the midline extending from the spinous process of C1 to just above the inion.…”

“…1,2 These regions harbor diverse pathological entities including primary pineal tumors, gliomas, meningiomas, cavernous malformations, and arteriovenous malformations. [2][3][4][5][6][7][8] To reach lesions in these regions, variants of the supracerebellar infratentorial approach (SCIT) are popular. 3,[9][10][11][12][13] The angle of approach, however, is restricted craniocaudally, and may prove insufficient for some lesions that extend inferiorly.…”

“…Although the supracerebellar approach and its variations have been compared with the occipital transtentorial approach by several qualitative and quantitative studies, none have described the comparative efficacy of the PCIT and the midline SCIT for lesions of the dorsal brainstem and cerebellomesencephalic fissure. 2,[15][16][17][18][19][20][21] In this study, we describe the different exposures afforded by the SCIT and PCIT from a practical standpoint and better identify their anatomic and surgical indications.…”

“…Thus, to provide a greater superior to inferior trajectory, recent publications have demonstrated the efficacy of the precuneal interhemispheric transtentorial approach (PCIT). 2,3,6,14 The PCIT maximizes the craniocaudal trajectory of a supratentorial corridor by shifting the craniotomy superiorly and, consequently, the trajectory inferiorly. Although the supracerebellar approach and its variations have been compared with the occipital transtentorial approach by several qualitative and quantitative studies, none have described the comparative efficacy of the PCIT and the midline SCIT for lesions of the dorsal brainstem and cerebellomesencephalic fissure.…”

“…1,2 These regions harbor diverse pathological entities including primary pineal tumors, gliomas, meningiomas, cavernous malformations, and arteriovenous malformations. 2-8…”