Microsurgical and Tractographic Anatomical Study of Transtemporal-Transchoroidal Fissure Approaches to the Ambient Cistern.

BACKGROUND: Approaching ambient cistern lesions is still a challenge because of deep location and related white matter tracts (WMTs) and neural structures. OBJECTIVE: To investigate the white matter anatomy in the course of 3 types of transtemporal-transchoroidal fissure approaches (TTcFA) to ambient cistern by using fiber dissection technique with translumination and magnetic resonance imaging fiber tractography. METHODS: Eight formalin-fixed cerebral hemispheres were dissected on surgical corridor from the temporal cortex to the ambient cistern by using Klingler's method. The trans-middle temporal gyrus, trans-inferior temporal sulcus (TITS), and trans-inferior temporal gyrus (TITG) approaches were evaluated. WMTs that were identified during dissection were then reconstructed on the Human Connectome Project 1021 individual template for validation. RESULTS: The trans-middle gyrus approach interrupted the U fibers, arcuate fasciculus (AF), the ventral segment of inferior frontoocipital fasciculus (IFOF), the temporal extensions of the anterior commissure (AC) posterior crura, the tapetum (Tp) fibers, and the anterior loop of the optic radiation (OR). The TITS approach interrupted U fibers, inferior longitudinal fasciculus (ILF), IFOF, and OR. The TITG approach interrupted the U fibers, ILF, and OR. The middle longitudinal fasciculus, ILF, and uncinate fasciculus (UF) were not interrupted in the trans-middle gyrus approach and the AF, UF, AC, and Tp fibers were not interrupted in the TITS/gyrus approaches. CONCLUSION: Surgical planning of the ambient cistern lesions requires detailed knowledge about WMTs. Fiber dissection and tractography techniques improve the orientation during surgery and may help decrease surgical complications.

Subdural Hematoma Evacuation via Rigid Endoscopy System: A Cadaveric Study.

ABSTRACT: The utilization of endoscope-assisted surgery is becoming a more common modality for the surgical treatment of subdural collections. Considering the inflexible construction of the rigid endoscope, it's not clear where to perform the optimal craniotomy. Twenty four craniotomies (3 cm diameter) were performed in 8 hemicrania. The craniotomies were placed 1 cm front and behind the coronal suture and to the point where the parietal bone was the most convex. The craniotomies in the anterior (C1) and posterior (C2) of the coronal suture were in the mid pupillary line, while the posterior craniotomy (C3) was just lateral to the midpupillary line. At first, subdural distances measured, and then the distances from the craniotomy to the anterior, posterior, medial, and lateral directions in which endoscope could reach the farthest without the damage to the parenchyma were measured. The subdural distance was significantly deeper in C3 than C1 (P = 0.001); however, there was no difference between C3 and C2 (P = 0.312). The distance that could be reached with C3 was higher than C1 in anterior, posterior, lateral, and medial directions (P ≤0.001, 0.037, <0.001, and <0.001, respectively). The distance that could be reached with C3 was higher than C2 in anterior, posterior, lateral, and medial directions (P < 0.001, 0.02, 0.01 and <0.001, respectively). In subdural hematomas, especially that covers all surface of the hemisphere, the most suitable craniotomy is the posteriorly placed craniotomy to reach the most extended projection in anteroposterior line of the hematoma.