Pericallosal artery aneurysm endovascular treatment
Neurosurgery Department, University General Hospital of Alicante, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Alicante, Spain
The initial results of endovascular coiling for pericallosal artery aneurysms were not satisfactory because most aneurysms in this location are small and distally located 1).
Since the recent improvements in endovascular techniques and equipment, pericallosal artery aneurysms have become accessible for endovascular coiling and the results have thus been improving with success rates to be 92.9–100% 2) 3) 4).
Intracranial hemorrhage (ICH) associated with this aneurysm location is not uncommon, and is viewed as a relative contraindication for heparinization and requires management of increased intracranial pressure. Par- ticular attention must be paid to perioperative management and coiling is still considered to be controversial. Thus, these conditions have resulted in under-utilization of endovascular therapy and un- der-representation in coiling trials.
Yamazaki et al. applied endovascular coiling for ruptured pericallosal artery aneurysms, including those associated with ICH, as the first-line treatment.
They consider to be important to refrain from bolus heparin injection during endovascular coiling for cases with concomitant dense hematoma. Otherwise, coil embolization should be postponed until 8 hours after the onset to lower the risk of hematoma enlargement 5).
Endovascular approaches for aneurysms < 3mm in size reportedly have higher risks for intraoperative rupture 6). 7).
30 consecutive patients with ruptured pericallosal artery aneurysms including those with intracerebral hematoma. Twenty-seven cases of ruptured pericallosal artery aneurysms were successfully embolized with coiling whereas three failures required surgery. Four patients experienced periprocedural complications including thromboembolic event in two and hematoma enlargement after coiling in two. A maximum aneurysm diameter of <3 mm was most strongly associated with failure of endovascular coiling. Of the 27 coil-treated aneurysms, immediate angiographic results showed complete aneurysm occlusion in 19 cases, neck remnant in 6, and residual aneurysm in 2. One patient had a major aneurysm recurrence that was uneventfully reembolized. Sixteen of our 30 patients had good outcomes (modified Rankin scale [mRS] 0-2), 7 had moderate disability (mRS 3), and 4 had severe disability (mRS 4-5) at 3 months after treatment. The management strategy for coiling as the first-intention treatment for ruptured pericallosal artery aneurysms has the potential to become an acceptable alternative to surgical clipping for selected cases, although a larger study population and longer follow-up periods are needed before definitive conclusions can be drawn.
The maximum diameters of our failed cases were < 3 mm while all 22 aneurysms with a maximum diameter ≥ 3 mm were successfully embolized. Therefore, morphologically, they consider the lower limit on pericallosal artery aneurysm diameters difficult to treat by endovascular coiling to be < 3mm since the failure rate was significantly higher than for larger aneurysms.
The overall complication rate was 13.3% (4/30 cases) and independent activities of daily living (mRS 0–2) were achieved in 53.3% (16/30). Two cases experienced thromboembolic complications with one resulting in a moderate permanent deficit and the other in a minor neurological deficit from which the patient fully recovered. Two patients developed hematoma enlargement probably because coil embolization was performed within 8 hours of onset under systemic heparinization. It is, therefore, important to intentionally postpone endovascular coiling in patients with associated ICH until 8 hours after the onset, or to minimize heparinization for patients requiring coil embolization within 8 hours. This may lower the risk of hemorrhagic complications 8).
Parent vessel trapping with Onyx 18/34 offers a simple, safe, and effective means of achieving obliteration of distal challenging aneurysms reported in 3 cases 9).
4 cases treating wide-neck pericallosal artery aneurysms at the bifurcation with Y-configuration stent placement is feasible and effective. This technique may be considered as a therapeutic option for wide-neck aneurysms that pose a difficult technical challenge 10).
32 patients presenting with SAH due to pericallosal aneurysm treated with an endovascular approach were more likely to have a good modified Rankin scale (mRS) (mRS 0-2 vs 3-6) (p=0.028), to make a complete recovery (mRS=0) (p=0.017) and were less likely to die (mRS=6) (p=0.026). Patients with electively treated pericallosal aneurysms did not have statistically significant differences in outcome between surgical and endovascular cohorts. Differences in secondary endpoints did not reach significance. Patients with ruptured pericallosal aneurysms fare better with endovascular therapy, with better chance of complete recovery. Surgical and endovascular treatments of unruptured pericallosal aneurysms have similar results and outcome 11).
Nguyen et al., examined data of 25 patients that were stored in a prospectively collected database for pericallosal artery aneurysms in patients who underwent coil placement between 1992 and 2005. Hemorrhagic and thromboembolic complications as well as clinical and angiographic outcomes were reviewed. Angiographically documented recurrences were classified as minor or major. These lesions were compared with a historical cohort of non-pericallosal artery aneurysms in patients who underwent coil therapy between 1992 and 2002. The known risk factors for recurrence and procedure-related hemorrhagic complications were evaluated in both groups to assess baseline imbalances.
During a 13-year period, 25 pericallosal artery aneurysms were treated with coils in 25 patients. The non-pericallosal artery lesion group included 488 aneurysms of which 344 underwent follow-up imaging. Procedure-related perforations were more frequent for pericallosal artery aneurysms than those in other intradural locations (three of 25 compared with eight of 476, respectively; risk ratio 7.1, 95% confidence interval [CI] 2.1-22.5, p = 0.03). Follow-up imaging studies (obtained at a mean 28 months) were available for 19 patients with pericallosal artery aneurysms. The recurrence rate was not significantly higher in these patients (22.9/100 person-years of observation) than in those with non-pericallosal artery aneurysms (17.9/100 person-years of observation) (incidence rate ratio 1.3, 95% CI 0.6-2.4, p = 0.46).
Pericallosal artery aneurysms were associated with significantly higher periprocedural rupture than non-pericallosal artery lesions. No significant intergroup difference was found for aneurysm recurrence 12).
A rare unique case of ruptured fusiform proximal pericallosal artery aneurysm. Endovascular treatment of this type of aneurysm is a feasible method and can be considered as an effective alternative to surgical technique 13).
A 35-year-old with bacterial endocarditis from Streptococcus mitis was diagnosed with a ruptured 3 mm MIA of the pericallosal anterior cerebral artery after episodic diplopia. The MIA was successfully treated with stent-assisted coil embolization utilizing a Neuroform EZ stent (Stryker Neuroendovascular, Kalamazoo, MI, USA). Follow-up magnetic resonance angiography at 3months demonstrated complete aneurysm obliteration, and the patient was neurologically intact. In the literature, a M1 segment middle cerebral artery MIA, bilateral cavernous carotid MIA, and a unilateral cavernous carotid MIA were also successfully treated with Neuroform, Helistent (Hexacath, Rueil-Malmaison, France), and SILK (BALT Extrusion, Montmorency, France) stents, respectively. We present the first patient with a pericallosal MIA treated with stent-assisted coil embolization. Proper treatment of the causative organism with antibiotics minimizes the risk of infectious seeding of the stent. Intracranial stenting may be safely and effectively utilized to treat select cases of MIA 14).
Endovascular treatment of traumatic pericallosal artery aneurysms. A case report 15).
A 54-year-old woman who underwent endovascular treatment in the setting of a massive subarachnoid haemorrhage due to rupture of a dissecting basilar trunk aneurysm treated with stent implantation and coiling. A further saccular aneurysm in the left pericallosal artery disclosed by four-vessel angiography was treated with coiling during the same procedure. Follow-up DSA performed after six months confirmed complete occlusion of both aneurysms and patency of the stent 16).