Ruptured PICA Aneurysms: Treatment Outcomes and Comparison with other Ruptured Posterior Circulation Aneurysms

Aims: Posterior circulation aneuryms account for 10% of intracranial aneuryms and PICA aneurysms represent a small subgroup (0.5–3%) of patients who present with an aneurismal subarchnoid hemorrhage aSAH). We performed a subgroup analysis of the results following treatment of PICA versus non-PICA posterior circulation aneurysms from the Swiss SOS registry.

Methods: Patients’ records of 264 posterior circulation aSAH were reviewed from January 1st 2009 to December 31st 2015 from the Swiss SOS registry. Mean age was 55.8 years (16–88), 76.8 female and 23.1% males. PICA was the second more frequent location (28.3%) after basilar tip aneurysms (32.3%). Other non-PICA aneurysm locations: vertebral artery (VA, 14.3%); posterior cerebral artery (PCA, 7.2%), basilar trunk (6.8%). superior cerebellar artery (SCA, 4.9%), AICA (2.6%), P2 (2.2%), Vertebro-Basilar (0.76).

The clinical outcome at discharge were assessed using: the modified Rankin score (mRS) divided into good (mRS ≤ 2), poor (≥ 3 mRS ≤5), dead (mRS=6); the Glasgow Outcome Scale Extended (GOSE) divided into good (≥ 5 GOSE ≤8), bad (≥ 2 GOSE ≤4), dead (GOSE=1) Ordinal variables were compared with the Kruskal-Wallis test among 3 groups, with the Mann-Whitney test among 2 groups.

Categorical variables were compared with the chi-square test and the Fisher exact test.

Results: The PICA group accounted for 74 aneurysms and the non-PICA group for 190 aneurysms.

The clinical and radiological severity of SAH in terms of WFNS score, Fisher and BNI grade was similar between PICA aneurysms and other posterior circulation aneurysms.

Most posterior circulation aneurysms were treated using endovascular procedures (stent, coiling, and combination), no significant difference was found between treatment distribution among PICA vs non-PICA aneurysms.

No significant difference was demonstrated between both groups regarding development of hydrocephalus, EVD placement, vasospasm requiring dilatation, delayed ischemic neurologic deficit (DIND) and re-rupture rate.

mRS at discharge was good in 66.8% of PICA pateints and 52% of non PICA patients with a significant difference toward a better outcome for PICA aneurysms (p = 0.04). The difference in mRS between both PICA and non-PICA aneurysms was maintained at 1 year follow up (p = 0.04) but the mRS at 5 years was similar among both groups (p = 0.55).

GOSE at discharge was good in 58.7% of PICA patients versus 41.8% of other aneurysms locations (p = 0.07). GOSE at 1 and 5 years follow up was comparable among both PICA and non-PICA aneurysms (p = 0.08 and p = 0.66 respectively).

Conclusions: PICA is a prevalent location for posterior circulation aneurysms where treatments remain challenging due to their variable anatomic features, reduced working space and proximity to lower cranial nerves. In our series, the outcomes following treatment for PICA aneurysms shows a trend toward better results than other posterior circulation aneurysms (p = 0.04) at discharge and at 1year with no difference at 5 years of follow up. Our findings are in contrast with previously described results in literature for PICA aneurysms.

No conflict of interest has been declared by the author(s).