TS-ACP classification provided a high-sensitivity CTA-based estimate of the operative intradural category, and prespecified geometry was strongly associated with contralateral corridor selection, with no excess permanent visual morbidity observed in carefully selected contralateral cases.
CTA-based TS-ACP classification matched operative distal dural ring (DDR) assessment in 90.5% of paraclinoid aneurysms with substantial inter-rater agreement.
TS-ACP classification demonstrated 100% sensitivity and 100% negative predictive value for identifying the operative intradural category.
Favorable interoptic geometry was significantly more frequent among patients selected for contralateral interoptic clipping compared to ipsilateral clipping.
Permanent visual worsening at 12 months occurred in 7 of 75 ipsilateral cases and 1 of 30 contralateral cases, with no statistically significant difference between groups.
CTA/DSA-confirmed complete aneurysm occlusion was achieved in 92.9% of patients.
This research suggests that a CT angiography (CTA)-based measurement system called the TS-ACP classification can reliably predict the surgical characteristics of paraclinoid aneurysms — abnormal bulges in blood vessels near the base of the brain — before an operation begins. In a group of 105 patients treated over 13 years, the preoperative CT scan correctly identified the key surgical anatomy in over 90% of cases, and crucially, it never missed cases where the aneurysm was located in a surgically important intradural (inside the protective brain lining) position, meaning surgeons could use this tool with confidence to avoid underestimating surgical complexity. The study also examined a less common surgical approach called contralateral interoptic clipping, where the surgeon approaches the aneurysm from the opposite side, passing between the optic nerves. This approach was much more likely to be chosen when the patient's anatomy showed favorable geometry — a wide enough corridor between the optic nerves. Patients selected for the contralateral approach did not appear to have higher rates of permanent vision worsening compared to those who had the more conventional ipsilateral approach (1 in 30 vs. 7 in 75), though the study was too small to draw firm conclusions about safety differences. This research suggests that detailed preoperative CTA imaging, analyzed using the TS-ACP classification, can meaningfully guide surgical planning for these complex aneurysms. Surgeons may be able to use this information to select the safest surgical corridor before the operation, potentially improving outcomes. However, because patients were not randomly assigned to different surgical approaches and the number of adverse events was small, larger prospective studies would be needed to confirm whether one approach is truly safer than the other in appropriately selected patients.
Seddighi A, Seddighi A, Hosseini S. (2026). CTA-based planning for clipping of paraclinoid aneurysms: TS-ACP validation and selective contralateral interoptic outcomes.. Clinical neurology and neurosurgery. https://doi.org/10.1016/j.clineuro.2026.109626