Background Insular surgery remains technically demanding because of the region’s deep location and intimate relationships with the middle cerebral artery complex and surrounding white matter pathways. Safe resection requires precise understanding of vascular landmarks and subcortical functional boundaries. Methods Eight formalin-fixed adult cadaveric heads (16 hemispheres) underwent bilateral two-piece orbitozygomatic (OZ) transsylvian (TS) dissections. Endoscopic assistance (0° and 30°) was used selectively to enhance visualization of deep and anatomically concealed regions. Following cortical exposure, approach-oriented subinsular fiber separation and dedicated hemispheric Klingler fiber dissections were performed to define operative surgical boundaries and characterize the three-dimensional organization of the peri-insular white matter. Results The OZ–TS corridor provided wide anterior and anteroinferior exposure of the insula, allowing early identification of the M2 trunks, M3 opercular branches, and lenticulostriate arteries, thereby clarifying the medial vascular limit. Endoscopic assistance provided complementary visualization of the limen insulae, anterior perforated substance, and deep perforators while maintaining the established operative corridor. Layered subinsular dissection consistently revealed the extreme capsule, claustrum, external capsule with its uncinate fasciculus and inferior fronto-occipital fasciculus (IFOF), followed by the putamen and internal capsule. The IFOF formed a critical medial boundary in anterior resections, whereas the posterior limb of the internal capsule and optic radiation defined posteromedial and posterior functional limits. Conclusion Endoscope-assisted OZ–TS exposure combined with a structured fiber-separation strategy provides an integrated anatomical perspective of the insular region. Early identification of vascular landmarks and systematic progression along intrinsic white matter planes facilitate anatomical definition of subcortical surgical boundaries.

Background and Objectives: Endoscope-assisted posterior fossa decompression with duraplasty (PFDD) is a minimally invasive alternative treatment for Chiari I malformation; however, its comparative effectiveness remains unclear. Therefore, this study aimed to compare the outcomes of conventional open decompression with those of endoscope-assisted minimally invasive decompression combined with duraplasty to assess the balance between limited surgical exposure and associated technical challenges. Materials and Methods: This retrospective single-center study compared 22 patients who underwent endoscope-assisted PFDD with a historical cohort of 16 patients treated with conventional open PFDD. Patients with C1–2 instability, prior craniovertebral surgery, or concomitant pathology requiring an alternative surgical strategy were excluded. The clinical outcomes, radiological findings, surgical variables, and complications were analyzed. Results: Clinical improvement, overall recovery, and 3-month Chicago Chiari Outcome Scale (CCOS) scores were comparable between the groups. The endoscopic group had higher CCOS scores at discharge. Syrinx resolution rates were similar, whereas postoperative cisterna magna expansion was more limited in the endoscopic cohort. The endoscopic approach was associated with a significantly shorter incision length and earlier mobilization. The rates of complications, including pseudomeningocele, cerebrospinal fluid fistula, and wound infection, did not differ significantly between the groups. Conclusions: Endoscope-assisted PFDD may be a less invasive alternative with comparable short-term clinical and radiological outcomes. Despite the technical challenges related to a limited working corridor, it can be considered a feasible option for selected patients.