Preoperative visualization and intraoperative functional assessment of a long medullary artery in glioblastoma surgery using ultra–high-resolution intra-arterial Computed tomography angiography: an illustrative case

BACKGROUND: Maximal safe resection is essential in glioblastoma (GB) surgery, but injury to perforating arteries supplying the corticospinal tract can result in irreversible motor deficits. Long medullary arteries (LMAs), which supply the corticospinal tract and function as end arteries, are particularly important yet cannot be visualized reliably with conventional imaging. Ultra-high-resolution intra-arterial CT angiography (UHR-IA-CTA) enables depiction of perforators smaller than 100 µm, offering a potential solution to this limitation. CASE DESCRIPTION: A 54-year-old man presented with focal seizures and progressive dysarthria. MRI revealed a bilobed enhancing lesion in the left postcentral gyrus, suspicious of GB. Preoperative UHR-IA-CTA combined with diffusion tensor tractography identified an LMA arising from the postcentral sulcus and coursing adjacent to the tumor before supplying the corticospinal tract. Because resection along with the enhancing margin risked injuring this artery, a limited residual tumor area was planned.Intraoperatively, motor evoked potential (MEP) monitoring was used to assess the functional significance of the LMAs. Temporary clipping of the cortical artery from which the LMAs identified preoperatively originated resulted in immediate loss of MEPs, confirming that it is a critical vessel supplying the corticospinal tract. After clip removal, MEPs recovered. Tumor removal was performed while preserving the artery, leaving only the planned remnant. No postoperative motor deficits or ischemic changes were observed, and the patient recovered with a Karnofsky Performance Status of 90. CONCLUSION: This case demonstrates that UHR-IA-CTA, combined with tractography and intraoperative electrophysiology, enables precise identification of critical LMAs supplying the motor pathway. Preoperative recognition of perforator-tumor relationships can directly influence surgical strategy and prevent irreversible neurological injury.