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

OBJECTIVE

The authors investigated the specific topographic relationship of the optic radiation fibers to the roof and floor of the ventricular atrium because the current literature is ambiguous.

METHODS

Thirty-five normal, adult, formalin-fixed cerebral hemispheres and 30 focused MRI slices at the level of the atrium were included in the study. The correlative anatomy of the optic radiation with regard to the atrial roof and floor was investigated in 15 specimens, each through focused fiber microdissections. The remaining 5 hemispheres were explored with particular emphasis on the trajectory of the collateral sulcus in relation to the floor of the atrium. In addition, the trajectory of the collateral sulcus was evaluated in 30 MRI scans.

RESULTS

The atrial roof was observed to be devoid of optic radiations in all studied hemispheres, whereas the atrial floor was seen to harbor optic fibers on its lateral part. Moreover, the trajectory of the intraparietal sulcus, when followed, was always seen to correspond to the roof of the atrium, thus avoiding the optic pathway, whereas that of the collateral sulcus was found to lead to either the lateral atrial floor or outside the ventricle in 88% of the cases, therefore hitting the visual pathway.

CONCLUSIONS

Operative corridors accessing the ventricular atrium should be carefully tailored through detailed preoperative planning and effective use of intraoperative navigation to increase patient safety and enhance the surgeon's maneuverability. The authors strongly emphasize the significance of accurate anatomical knowledge.

Interhemispheric, Translamina Terminalis Approach for the Resection of Suprasellar Cavernous Malformation

Objectives  The current video presents the nuances of an interhemispheric, translamina terminalis approach for the resection of suprasellar cavernous malformation.

Design  The video analyzes the presentation, preoperative workup and imaging, surgical steps and technical nuances of the surgery, the clinical outcome, and follow-up imaging.

Setting  The patient was treated by a skull base team at a teaching academic institution.

Participants  The case refers to a 64-year-old female who presented with vision loss and confusion, and was found to have a suprasellar mass, with imaging characteristics consistent with a cavernous malformation of the third ventricle.

Main Outcome Measures  The main outcome measures consist of the reversal of the patient symptoms (vision loss and confusion), the recurrence-free survival based on imaging, as well as the absence of any complications.

Results  The patient's mental status improved slightly after surgery. There was no evidence of recurrence.

Conclusions  The interhemispheric, translamina terminalis approach is safe and effective for the resection of suprasellar cavernous malformations.

The link to the video can be found at: https://youtu.be/z6RSAM_GnBA .

The cerebral isthmus: fiber tract anatomy, functional significance, and surgical considerations

OBJECTIVE

The cerebral isthmus is the white matter area located between the periinsular sulcus and the lateral ventricle. Studies demonstrating the fiber tract and topographic anatomy of this entity are lacking in current neurosurgical literature. Hence, the authors' primary aim was to describe the microsurgical white matter anatomy of the cerebral isthmus by using the fiber dissection technique, and they discuss its functional significance. In addition, they sought to investigate its possible surgical utility in approaching lesions located in or adjacent to the lateral ventricle.

METHODS

This study was divided into 2 parts and included 30 formalin-fixed cerebral hemispheres, 5 of which were injected with colored silicone. In the first part, 15 uncolored specimens underwent the Klinger's procedure and were dissected in a lateromedial direction at the level of the superior, inferior, and anterior isthmuses, and 10 were used for coronal and axial cuts. In the second part, the injected specimens were used to investigate the surgical significance of the superior isthmus in accessing the frontal horn of the lateral ventricle.

RESULTS

The microsurgical anatomy of the anterior, superior, and inferior cerebral isthmuses was carefully studied and recorded both in terms of topographic and fiber tract anatomy. In addition, the potential role of the proximal part of the superior isthmus as an alternative safe surgical corridor to the anterior part of the lateral ventricle was investigated.

CONCLUSIONS

Using the fiber dissection technique along with coronal and axial cuts in cadaveric brain specimens remains a cornerstone in the acquisition of thorough anatomical knowledge of narrow white matter areas such as the cerebral isthmus. The surgical significance of the superior isthmus in approaching the frontal horn of the lateral ventricle is stressed, but further studies must be carried out to elucidate its role in ventricular surgery.