A Case of Proximal Posterior Inferior Cerebellar Artery (PICA) Aneurysm Treated with PICA-to-PICA Bypass and Trapping Surgery: Comparison with Occipital Artery-PICA Bypass

Posterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery Bypass versus Occipital Artery-Posterior Inferior Cerebellar Artery Bypass for Treating Posterior Circulation Aneurysms: A Systematic Review and Comparative Meta-Analysis

BACKGROUND

When traditional therapies are unsuitable, revascularization becomes essential for managing posterior inferior cerebellar artery (PICA) or vertebral artery aneurysms. Notably, the PICA-PICA bypass has emerged as a promising option, overshadowing the occipital artery-PICA (OA-PICA) bypass. The objective was to compare the safety and efficacy of OA-PICA and PICA-PICA bypasses.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, we conducted a systematic review and meta-analysis to evaluate the safety and efficacy of OA-PICA and PICA-PICA bypasses for treating posterior circulation aneurysms.

RESULTS

We analyzed 13 studies for the PICA-PICA bypass and 16 studies on the OA-PICA bypass, involving 84 and 110 patients, respectively. The median average follow-up for PICA-PICA bypass was 8 months (2-50.3 months), while for OA-PICA, it was 27.8 months (6-84 months). The patency rate for OA-PICA was 97% (95% confidence interval [CI]: 92%-100%) and 100% (95% CI: 95%-100%) for PICA-PICA. Complication rates were 29% (95% CI: 10%-47%) for OA-PICA and 12% (95% CI: 3%-21%) for PICA-PICA. Good clinical outcomes were observed in 71% (95% CI: 52%-90%) of OA-PICA patients and 87% (95% CI: 75%-100%) of PICA-PICA patients. Procedure-related mortality was 1% (95% CI: 0%-6%) for OA-PICA and 1% (95% CI: 0%-10%) for PICA-PICA.

CONCLUSIONS

Both procedures have demonstrated promising results in efficacy and safety. PICA-PICA exhibits slightly better patency rates, better clinical outcomes, and fewer complications, but with a lack of substantial follow-up and a smaller sample size. The choice between these procedures should be based on the surgeon's expertise and the patient's anatomy.

End-to-end revascularization between the occipital Artery(OA) and the p1 segment of posterior inferior cerebellar Artery(PICA) for a patient with posterior circulation ischemia via a far-lateral approach:2-Dimensional Operative video

Vertebral artery （VA）Aneurysms involving the origin of the posterior inferior cerebellar artery (PICA) ,occasionally, induce cerebellum and brainstem infarction due to intraluminal thrombus and calcific VA stenosis. At times, vessel occlusion and revascularization is necessary for successful obliteration of these aneurysms.2 The occipital artery (OA) is often the preferred donor graft for lesions of the posterior fossa. Although most OA-PICA bypasses can be performed using the p3 segment as the recipient site for an end-to-side anastomosis, a more feasible alternative to conventional OA-p3 PICA bypass in cases of high-riding caudal loops , aberrant anatomy or p3 multiple perforators is to free the p1 PICA, transpose it away from the lower cranial nerves, and perform an end-to-end OA-p1 PICA bypass instead. This video captures the dissection of the OA using an orientational anterograde harvesting technique and the end-to-end anastomosis of the OA to the PICA at the p1 segment. This was performed in a 56-year-old man who presented with posterior circulation ischemia from a fusiform aneurysm with calcific vertebral artery stenosis located at the origin of the right PICA. The patient tolerated the procedure well and suffered no major complications related to the operation. He did experience some mild, posterior neck rigidity at the time of his 6-month follow-up, likely due to nerve injury that occurred while harvesting the OA. Overall, the patient remains in good neurologic status 1 year after the operation. The operation proved the feasibility of end-to-end bypass in OA-p1 PICA.

Occipital artery-to-PICA bypass: how I do it

BACKGROUND

Posterior inferior cerebellar artery (PICA) aneurysms are uncommon, and their management is challenging because of the complex angioarchitecture of the PICA and the frequently nonsaccular aneurysm presentation. Endovascular therapy may not be feasible.

METHODS

We describe our technique of clip trapping with occipital artery (OA)-to-PICA bypass to treat a PICA aneurysm. Because the aneurysm affected the ipsilateral, dominant PICA, an OA-PICA bypass was chosen to ensure adequate flow and reduce risk to the contralateral PICA supply.

CONCLUSION

The OA-PICA anastomosis is a safe and effective method to successfully achieve flow preservation with bypass reconstruction and aneurysm trapping.

Occipital artery-posterior inferior cerebellar artery bypass: a cadaveric feasibility study

PURPOSE

To demonstrate that occipital artery (OA)-p1 posterior inferior cerebellar artery (PICA) bypass can be an alternative for complex posterior circulation aneurysms.

METHODS

A far-lateral approach to craniotomy was performed on 20 cadaveric specimens, and the OA was obtained 'in-line.' Its length, diameter, and the number of p1/p2 and p3 segmental perforators were determined, and the relationship between the caudal loop and cerebellar tonsil position was also assessed. The distance between the PICA's origin and the cranial nerve XI (CN XI), the buffer length above the CN XI after dissection, the OA length required to complete the OA-p1/p3 PICA bypass, and the p1 and p3 segment diameters were all measured. A bypass training practical scale (TSIO) was used to evaluate the quality of the anastomosis.

RESULTS

All specimens underwent OA-p1 PICA end-to-end bypass and had favorable results for the TSIO score, 15 sides underwent OA-p3 PICA end-to-side bypass, and the other bypass protocols were less common. The buffer length above the CN XI after dissection, the distance between the PICA's origin and the CN XI, and the first perforator were all of sufficient length. The direct length of the OA needed to complete the OA-p1 PICA end-to-end bypass was significantly less than the available length and the OA-p3 PICA end-to-side bypass, with the OA matching the p1 segment diameter. The number of p1 perforators was less than that of p3, and the OA diameter was equal to that of the p1 segment.

CONCLUSION

OA-p1 PICA end-to-end bypass is a feasible alternative in cases in which p3 segment has high caudal loops or anatomic anomalies.