2026 Poster Presentations
P343: THE CONTRALATERAL TRANSFALCINE APPROACH: AN ANATOMICAL STUDY QUANTIFYING ITS SUPERIOR AND LATERAL LIMITS OF EXPOSURE
A. Yohan Alexander1,2,3; Stephen Graepel, MA2; Maria Peris-Celda, MD, PHD1,2,4,5; Giuseppe Lanzino, MD1,2; 1Rhoton Neurosurgery and Otolaryngology Surgical Anatomy Program, Mayo Clinic, Rochester, MN; 2Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA; 3Medical School, University of Minnesota, Minneapolis, MN, USA; 4Department of Otorhinolaryngology, Mayo Clinic, Rochester, MN, USA; 5Department of Clinical Anatomy, Mayo Clinic, Rochester, MN, USA
Introduction: The contralateral transfalcine approach can address select lesions near the interhemispheric fissure. No study defines the maximal lateral or superior limits of the approach once the falx has been removed. Thus, this anatomical study aims to define the maximal superior and lateral limits of exposure using contralateral transfalcine approach.
Methods: On 10 embalmed latex injected specimens, we performed parasagittal craniotomies and interhemispheric approaches in the anterior, middle, and posterior-thirds of the interhemispheric fissure. The specimen was placed in a hypothetical lateral position. For all approaches, the side ipsilateral to the hypothetical lesion was superior. To reach the mesial surface of the contralateral hemisphere, a rectangular falcine incision was made and, superiorly, it was carried as far as possible under direct visualization. The contralateral hemisphere was resected as lateral as possible from the superior point of visualization down to the axial level of the corpus callosum. The distance between the most superior point of visualization of the contralateral hemisphere and the most superficial point of its cortex, and the distance between the midline and the lateral limit of visualization at the level of the corpus callosum were measured in millimeters (mm). Illustrative cases are also reviewed.
Results: At the anterior-third of the interhemispheric fissure, the superior point of visualization was on average 4.8 mm (2-7 mm) inferior to the superior aspect of the cortex. The mean lateral limit of visualization at the level of the genu of the corpus callosum was 22.9 mm (18-38 mm) lateral to the midline. At the middle-third, the mean superior point of visualization was 9.7 mm (7-14 mm) inferior to the superior aspect of the cortex. The mean lateral distance from midline visualized at the level of the body of the corpus callosum was 22.4 mm (16-31 mm). At the posterior-third, the superior point visualization of the mesial contralateral hemisphere was a mean of 12.6 mm (8-15 mm) inferior to the cortex. On average, the lateral distance visualized at the level of the splenium of the corpus callosum was 21.3 mm (17-28 mm) lateral to midline.
Conclusion: Using the contralateral transfalcine approach, the superior limit of visualization of the contralateral hemisphere is approximately 10 mm inferior to the superficial aspect of its cortex. The lateral reach afforded is approximately 20 mm lateral to midline at the depth of the approach. The more posterior the approach is along the interhemispheric fissure, the more limited the superior and lateral accesses to the contralateral hemisphere are due to the increasing caliber of the superior sagittal sinus, which obstructs the surgical line of sight.
