Navigare necesse est: The transorbital route to intraparenchymal temporal lesions

During the last years, the endoscopic transorbital approaches (ETOAs) have emerged as a minimally invasive alternative to traditional microsurgical transcranial approaches (MTAs) for accessing selected intraparenchymal temporal lesions, particularly those located in the temporopolar (pTL) and mediobasal temporal regions (mbTR). While certain MTAs approaches with a lateral-to-medial trajectory toward the mesial temporal lobe may pose a higher risk of optic radiation injury and consequent visual field (VF) deficits, ETOAs offer an anterior-to-posterior trajectory that may minimize such risks. This systematic review aims to assess the safety, efficacy, and technical aspects of ETOAs highlighting also the preservation of temporalis muscle integrity as an additional advantage of the transorbital approach. A systematic literature search was conducted according to PRISMA guidelines using PubMed, Scopus and Ovid MEDLINE to identify clinical studies evaluating ETOA for intraparenchymal temporal lesions. Inclusion criteria encompassed studies reporting clinical and/or surgical outcomes, including extent of resection (EoR), postoperative complications, and VF deficits. Descriptive statistics were applied. Additionally, illustrative clinical cases were reviewed to highlight technical nuances. Thirteen studies met inclusion criteria, encompassing 41 patients. Most lesions were in the mbTR (87.8%), with a smaller number involving the temporal pole (12.2%). Gross total resection was achieved in 27 patients (73.0%), subtotal resection in 5 (13.5%), partial resection in 3 (8.1%), and biopsy alone in 2 (5.4%). Postoperative visual outcomes were favorable: of 29 patients with available data, 23 (79.3%) preserved their preoperative intact VF and none experienced postoperative VF deterioration. Complications were rare, with a single case (2.6%) of CSF leak and no instances of permanent cranial nerve deficits. Endoscopic transorbital route is a promising and versatile approach for selected intraparenchymal temporal lesions, offering a function-preserving alternative to conventional MTAs. Its anterior-to-posterior surgical corridor along the temporo-insular axis may facilitate reduced subcortical disruption, potentially allowing optic radiation sparing while preserving temporalis muscle integrity, further support its integration into neurosurgical practice. Clinical trial number: not applicable.