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Objective: The endoscopic endonasal approach (EEA), has become the preferred alternative to traditional open and transoral approaches to the ventral craniovertebral junction (CVJ) region. However, preoperative prediction of the limitations of caudal reach remains challenging. This cadaveric study aimed to quantify the CVJ area of exposure and access afforded by the EEA, evaluate the accuracy of previously described radiographic anthropometric lines, and identify the lowest limit of the EEA corridor. Methods: Endoscopic endonasal dissections of the CVJ were completed in 35 cadaveric specimens. The area of exposure (AoE) and caudal-most reach were measured using a navigation system. Radiographic measurements included the distance of the odontoid process from the hard palate, length of the hard palate, distance of the lowest point reached from the hard palate level, and angles such as the nasopalatine line (NPL) angle, nasoaxial line (NAxL) angle, nostril-hard palate line (NTL) angle, and rhinopalatine line (RPL) angle. Results: The mean CVJ AoE was 931.22 ± 79.36 mm2. The NPL, NAxL, and RPL angles showed significant negative correlations with the distance of the odontoid process from the hard palate line (r = -0.521, p = 0.001; r = -0.538, p = 0.001; r = -0.500, p = 0.002, respectively), while the NTL angle did not (r = -0.241, p = 0.162). No significant correlation was found between achieved AoE via EEA and NPL, NAxL, NTL, or RPL (p > 0.05). Importantly, hard palate length was the sole predictor of CVJ AoE variability (r = -0.416, p = 0.013), with shorter lengths associated with increased exposure. The mean distance of the lowest point reached in the AoE from the hard palate level was 9.47 ± 1.24 mm. Conclusions: This anatomic study highlights the variability in CVJ anatomy and the limitations of using previously defined radiographic anthropometric lines for predicting the caudal limits of the EEA. Hard palate length emerged as the only reliable predictor of the surgical area of exposure via the endonasal corridor. Clinical studies are warranted to validate these findings and define the potential need for adjunctive surgical routes in managing complex CVJ pathologies. [ABSTRACT FROM AUTHOR]

Background: Surgical resection of insular gliomas is a challenge. TO resection is considered more versatile and has lower risk of vascular damage. In this study, we aimed to understand the factors that affect resection rates, ischemic changes and neurological outcomes and studied the utility of IONM in patients who underwent TO resection for IGs. Methods: Retrospective analysis of 66 patients with IG who underwent TO resection was performed. Results: Radical resection was possible in 39% patients. Involvement of zone II and the absence of contrast enhancement predicted lower resection rate. Persistent deficit rate was 10.9%. Although dominant lobe tumors increased immediate deficit and fronto-orbital operculum involvement reduced prolonged deficit rate, no tumor related factor showed significant association with persistent deficits. 45% of patients developed a postoperative infarct, 53% of whom developed deficits. Most affected vascular territory was lenticulostriate (39%). MEP changes were observed in 9/57 patients. 67% of stable TcMEPs and 74.5% of stable strip MEPs did not develop any postoperative motor deficits. Long-term deficits were seen in 3 and 6% patients with stable TcMEP and strip MEPs respectively. In contrast, 25% and 50% of patients with reversible strip MEP and Tc MEP changes respectively had persistent motor deficits. DWI changes were clinically more relevant when accompanied by MEP changes intraoperatively, with persistent deficit rates three times greater when MEP changes occurred than when MEPs were stable. Conclusion: Radical resection can be achieved in large, multizone IGs, with reasonable outcomes using TO approach and multimodal intraoperative strategy with IONM. [ABSTRACT FROM AUTHOR]