Flow Diverters for Unruptured Internal Carotid Artery Aneurysms: Dangerous and Not Yet an Alternative for Conventional Endovascular Techniques

W.J. van Rooij; M. Sluzewski; C. van der Laak

doi:10.3174/ajnr.A3317

With interest, we read the article of Lanzino et al¹ about the use of flow diverters for proximal internal carotid artery aneurysms in 21 patients. There was a higher rate of complete occlusion at follow-up with flow diverters than in a matched series of aneurysms treated with conventional techniques (coiling, stent placement, ICA occlusion). Most important, there were no complications leading to permanent neurologic deficits or death, though 1 patient was found to have a complete ICA occlusion at 6 months without symptoms. The message in the article is that although longer follow-up is needed, flow diverters are probably better than conventional techniques for these ICA aneurysms because of a higher complete occlusion rate at follow-up.

The results in this study are exceptionally good (if we disregard the asymptomatic ICA occlusion at follow-up) and better than most previously reported series. Briganti et al² recently reported the initial experience with flow diverters in Italy and found, in a cohort of 273 patients with unruptured aneurysms, a morbidity of 3.7% and a mortality of 5.9% at 1-month follow-up. There were 7 delayed aneurysm ruptures in aneurysms that had never bled before treatment. In posterior circulation aneurysms, the mortality went up to an alarming 19% (7 of 37). In (harmless) cavernous sinus aneurysms, the mortality was still 4% (3 of 76). Briganti et al summarize the complications of 6 large studies on flow diverters. In 471 patients, the morbidity was 4.2% (95% confidence interval [CI], 2.7%–6.5%) and the mortality was 5.1% (95% CI, 3.4%–7.5%). Also in the French experience in 64 patients, combined morbidity and mortality were higher than 10%.³ This means that almost 1 of every 10 patients with an unruptured aneurysm either dies or ends up with permanent neurologic deficits directly related to the flow-diverter treatment. In addition, at follow-up, there remains a certain risk for delayed aneurysm rupture and delayed in-stent thrombosis. Velioglu et al⁴ combined their results with those of 4 other studies and found that in >11% (22 of 197) of aneurysms treated with a flow diverter, the parent artery became occluded. We must realize that this high complication rate and high rate of unintended parent vessel occlusion concerns elective treatments of unruptured aneurysms with an often low chance of rupture or a benign natural history (cavernous sinus aneurysms) for which safer conventional treatments are available.

In our practice, ICA balloon occlusion is still the first choice in the treatment of (large and giant) ICA aneurysms.⁵ Three-quarters of patients can tolerate ICA occlusion, and this tolerance can be safely and reliably tested with angiography.⁶ ICA occlusion is simple to perform without the need for anesthesia, is extremely effective, safe, definitive (no imaging follow-up needed), and cheap, and leads to aneurysm shrinkage and alleviation of symptoms of mass effect in most patients. Delayed aneurysm rupture does not occur.^5,7⇓–9 In contrast to the fear expressed by Lanzino et al,¹ there is no increased risk for the development of de novo aneurysms in the long term and also cerebral perfusion is not impaired very long after ICA occlusion.^10,11 Regardless, long-term risks after ICA occlusion are definitely much lower than the substantial risk of delayed aneurysm rupture and parent vessel occlusion after placement of flow diverters with intended preservation of the ICA.

In patients with unruptured aneurysms who cannot tolerate ICA occlusion (25% of patients), we should be reluctant to offer a treatment with a risk of delayed ICA occlusion with subsequent certain neurologic deficit or even death. Delayed ICA occlusion on follow-up may occur in >11% of cases with flow diverters, after filling the aneurysm with Onyx (ev3, Irvine, California), or after surgical bypass procedures. Selective coiling with or without stent assistance seems the safest option in these patients. In unruptured aneurysms, neck or aneurysm remnants on follow-up have little or no clinical consequences, not even in ruptured aneurysms,¹² and additional coiling can be performed at a low complication rate.^13,14 The risk of recurrence with conventional parent artery sparing techniques can never be an argument to proceed with dangerous flow-diverter treatment.

In patients presenting with unruptured aneurysms, our first goal is to do no harm. A treatment strategy with ICA occlusion when tolerated, selective coiling when necessary, and conservative treatment when possible (cavernous sinus aneurysms) has very low complication rates approaching 0% and is effective in preventing first-time SAH or in alleviating symptoms of mass effect and has no negative consequences in the long term. We welcome the good results of Lanzino et al¹ with flow diverters. Their results are as good as those they achieved with selective coiling in 126 mostly small paraclinoid aneurysms.¹⁵ However, one swallow does not make a summer. With 10% combined morbidity and mortality together with the risk of delayed aneurysm rupture and delayed parent vessel occlusion, flow diverters should, for now, be considered a dangerous therapy for unruptured aneurysms, especially in patients who cannot tolerate ICA occlusion.

References

1.↵
1. Lanzino G,
2. Crobeddu E,
3. Cloft HJ,
4. et al
. Efficacy and safety of flow diversion for paraclinoid aneurysms: a matched-pair analysis compared with standard endovascular approaches. AJNR Am J Neuroradiol 2012 Jul 12. [Epub ahead of print]
2.↵
1. Briganti F,
2. Napoli M,
3. Tortora F,
4. et al
. Italian multicenter experience with flow-diverter devices for intracranial unruptured aneurysm treatment with periprocedural complications: a retrospective data analysis. Neuroradiology 2012 May 9. [Epub ahead of print]
3.↵
1. Berge J,
2. Biondi A,
3. Machi P,
4. et al
. Flow-diverter Silk stent for the treatment of intracranial aneurysms: 1-year follow-up in a multicenter study. AJNR Am J Neuroradiol 2012;33:1150–55
Abstract/FREE Full Text
4.↵
1. Velioglu M,
2. Kizilkilic O,
3. Selcuk H,
4. et al
. Early and midterm results of complex cerebral aneurysms treated with Silk stent. Neuroradiology 2012 Jun 14. [Epub ahead of print]
5.↵
1. van Rooij WJ,
2. Sluzewski M
. Endovascular treatment of large and giant aneurysms. AJNR Am J Neuroradiol 2009;30:12–18
Abstract/FREE Full Text
6.↵
1. van Rooij WJ,
2. Sluzewski M,
3. Slob MJ,
4. et al
. Predictive value of angiographic testing for tolerance to therapeutic occlusion of the carotid artery. AJNR Am J Neuroradiol 2005;26:175–78
Abstract/FREE Full Text
7.↵
1. de Gast AN,
2. Sprengers ME,
3. van Rooij WJ,
4. et al
. Midterm clinical and magnetic resonance imaging follow-up of large and giant carotid artery aneurysms after therapeutic carotid artery occlusion. Neurosurgery 2007;60:1025–29
PubMed
8.↵
1. van Rooij WJ,
2. Sluzewski M
. Unruptured large and giant carotid artery aneurysms presenting with cranial nerve palsy: comparison of clinical recovery after selective aneurysm coiling and therapeutic carotid artery occlusion. AJNR Am J Neuroradiol 2008;29:997–1002
Abstract/FREE Full Text
9.↵
1. van Rooij WJ
. Endovascular treatment of cavernous sinus aneurysms. AJNR Am J Neuroradiol 2012;33:323–26
Abstract/FREE Full Text
10.↵
1. de Gast AN,
2. Sprengers ME,
3. van Rooij WJ,
4. et al
. Long-term 3T-MRA follow-up after therapeutic occlusion of the internal carotid artery to detect possible de novo aneurysm formation. AJNR Am J Neuroradiol 2007;28:508–10
Abstract/FREE Full Text
11.↵
1. Gevers S,
2. Heijtel D,
3. Ferns SP,
4. et al
. Cerebral perfusion long term after therapeutic occlusion of the internal carotid artery in patients who tolerated angiographic balloon test occlusion. AJNR Am J Neuroradiol 2012;33:329–35
Abstract/FREE Full Text
12.↵
1. Ferns SP,
2. Majoie CB,
3. Sluzewski M,
4. et al
. Late adverse events in coiled ruptured aneurysms with incomplete occlusion at 6-month angiographic follow-up. AJNR Am J Neuroradiol 2010;31:464–69
Abstract/FREE Full Text
13.↵
1. van Rooij WJ,
2. Sprengers ME,
3. Sluzewski M,
4. et al
. Intracranial aneurysms that repeatedly reopen over time after coiling: imaging characteristics and treatment outcome. Neuroradiology 2007;49:343–49
CrossRef PubMed
14.↵
1. Slob MJ,
2. Sluzewski M,
3. van Rooij WJ,
4. et al
. Additional coiling of previously coiled cerebral aneurysms: clinical and angiographic results. AJNR Am J Neuroradiol 2004;25:1373–76
Abstract/FREE Full Text
15.↵
1. D'Urso PI,
2. Karadeli HH,
3. Kallmes DF,
4. et al
. Coiling for paraclinoid aneurysms: Time to make way for flow diverters? AJNR Am J Neuroradiol 2012 Mar 8. [Epub ahead of print]

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[1] 1.↵
Lanzino G,
Crobeddu E,
Cloft HJ,
et al
. Efficacy and safety of flow diversion for paraclinoid aneurysms: a matched-pair analysis compared with standard endovascular approaches. AJNR Am J Neuroradiol 2012 Jul 12. [Epub ahead of print]

[2] Lanzino G,

[3] Crobeddu E,

[4] Cloft HJ,

[5] et al

[6] 2.↵
Briganti F,
Napoli M,
Tortora F,
et al
. Italian multicenter experience with flow-diverter devices for intracranial unruptured aneurysm treatment with periprocedural complications: a retrospective data analysis. Neuroradiology 2012 May 9. [Epub ahead of print]

[7] Briganti F,

[8] Napoli M,

[9] Tortora F,

[10] et al

[11] 3.↵
Berge J,
Biondi A,
Machi P,
et al
. Flow-diverter Silk stent for the treatment of intracranial aneurysms: 1-year follow-up in a multicenter study. AJNR Am J Neuroradiol 2012;33:1150–55
Abstract/FREE Full Text

[12] Berge J,

[13] Biondi A,

[14] Machi P,

[15] et al

[16] 4.↵
Velioglu M,
Kizilkilic O,
Selcuk H,
et al
. Early and midterm results of complex cerebral aneurysms treated with Silk stent. Neuroradiology 2012 Jun 14. [Epub ahead of print]

[17] Velioglu M,

[18] Kizilkilic O,

[19] Selcuk H,

[20] et al

[21] 5.↵
van Rooij WJ,
Sluzewski M
. Endovascular treatment of large and giant aneurysms. AJNR Am J Neuroradiol 2009;30:12–18
Abstract/FREE Full Text

[22] van Rooij WJ,

[23] Sluzewski M

[24] 6.↵
van Rooij WJ,
Sluzewski M,
Slob MJ,
et al
. Predictive value of angiographic testing for tolerance to therapeutic occlusion of the carotid artery. AJNR Am J Neuroradiol 2005;26:175–78
Abstract/FREE Full Text

[25] van Rooij WJ,

[26] Sluzewski M,

[27] Slob MJ,

[28] et al

[29] 7.↵
de Gast AN,
Sprengers ME,
van Rooij WJ,
et al
. Midterm clinical and magnetic resonance imaging follow-up of large and giant carotid artery aneurysms after therapeutic carotid artery occlusion. Neurosurgery 2007;60:1025–29
PubMed

[30] de Gast AN,

[31] Sprengers ME,

[32] van Rooij WJ,

[33] et al

[34] 8.↵
van Rooij WJ,
Sluzewski M
. Unruptured large and giant carotid artery aneurysms presenting with cranial nerve palsy: comparison of clinical recovery after selective aneurysm coiling and therapeutic carotid artery occlusion. AJNR Am J Neuroradiol 2008;29:997–1002
Abstract/FREE Full Text

[35] van Rooij WJ,

[36] Sluzewski M

[37] 9.↵
van Rooij WJ
. Endovascular treatment of cavernous sinus aneurysms. AJNR Am J Neuroradiol 2012;33:323–26
Abstract/FREE Full Text

[38] van Rooij WJ

[39] 10.↵
de Gast AN,
Sprengers ME,
van Rooij WJ,
et al
. Long-term 3T-MRA follow-up after therapeutic occlusion of the internal carotid artery to detect possible de novo aneurysm formation. AJNR Am J Neuroradiol 2007;28:508–10
Abstract/FREE Full Text

[40] de Gast AN,

[41] Sprengers ME,

[42] van Rooij WJ,

[43] et al

[44] 11.↵
Gevers S,
Heijtel D,
Ferns SP,
et al
. Cerebral perfusion long term after therapeutic occlusion of the internal carotid artery in patients who tolerated angiographic balloon test occlusion. AJNR Am J Neuroradiol 2012;33:329–35
Abstract/FREE Full Text

[45] Gevers S,

[46] Heijtel D,

[47] Ferns SP,

[48] et al

[49] 12.↵
Ferns SP,
Majoie CB,
Sluzewski M,
et al
. Late adverse events in coiled ruptured aneurysms with incomplete occlusion at 6-month angiographic follow-up. AJNR Am J Neuroradiol 2010;31:464–69
Abstract/FREE Full Text

[50] Ferns SP,

[51] Majoie CB,

[52] Sluzewski M,

[53] et al

[54] 13.↵
van Rooij WJ,
Sprengers ME,
Sluzewski M,
et al
. Intracranial aneurysms that repeatedly reopen over time after coiling: imaging characteristics and treatment outcome. Neuroradiology 2007;49:343–49
CrossRef PubMed

[55] van Rooij WJ,

[56] Sprengers ME,

[57] Sluzewski M,

[58] et al

[59] 14.↵
Slob MJ,
Sluzewski M,
van Rooij WJ,
et al
. Additional coiling of previously coiled cerebral aneurysms: clinical and angiographic results. AJNR Am J Neuroradiol 2004;25:1373–76
Abstract/FREE Full Text

[60] Slob MJ,

[61] Sluzewski M,

[62] van Rooij WJ,

[63] et al

[64] 15.↵
D'Urso PI,
Karadeli HH,
Kallmes DF,
et al
. Coiling for paraclinoid aneurysms: Time to make way for flow diverters? AJNR Am J Neuroradiol 2012 Mar 8. [Epub ahead of print]

[65] D'Urso PI,

[66] Karadeli HH,

[67] Kallmes DF,

[68] et al

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Flow Diverters for Unruptured Internal Carotid Artery Aneurysms: Dangerous and Not Yet an Alternative for Conventional Endovascular Techniques

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