Abstract
We present the case of a 49-year-old woman with sudden onset of severe headaches and a ruptured aneurysm located inside the fenestration of the infraclinoid part of the internal carotid artery in the segments C4 and C5 distal to the origin of the ophthalmic artery. An interdisciplinary approach enabled the successful treatment of the aneurysm by wrapping and stent-assisted coiling. We discuss this rare congenital anomaly of a fenestrated internal carotid artery together with the 12 other cases published worldwide.
Keywords: Internal carotid artery aneurysm, fenestrated internal carotid artery, infraclinoidal internal carotid artery
Introduction
Intracranial arterial fenestrations are rare congenital anomalies and occur only in about 0.7% of the population.1 In some cases, the fenestration is associated with the formation of an aneurysm, most commonly occurring in the vertebrobasilar circulation.2–4 Since 1984, 12 cases of aneurysms originating in a fenestration of the internal carotid artery (ICA) – four ruptured and eight unruptured aneurysms – have been published.1,5–13 It should be noted that in all these cases the supraclinoidal segments C6 and C7 of the ICA were concerned.
In this case report, we describe an aneurysm of a fenestrated right ICA in the segments C4 and C5 distal to the origin of the ophthalmic artery. To the best of the authors’ knowledge, no case has been published describing the finding of an aneurysm occurring in the infraclinoidal portion in segments C4 and C5 of a fenestrated ICA.
Case report
A 49-year-old woman presented in the emergency room with sudden onset of severe headaches without any further neurological symptoms for the first time in her life. Despite the classic clinical presentation of subarachnoid haemorrhage (SAH), no evidence of blood was found in the cranial computed tomogram as well as in the cranial magnetic resonance imaging scan (see Figure 1). However, the suspicion of an aneurysm of the ICA rose. The patient declined lumbar puncture to prove SAH. We performed a digital subtraction angiography. Figure 2 shows a dumbbell-shaped aneurysm located in the fenestrated C4 and C5 segments of the right ICA distal to the origin of the ophthalmic artery.
Figure 1.
(a) Non-contrast-enhanced computed tomography scan done on day one after the onset of severe headaches reveals no signs of subarachnoid haemorrhage. (b) Axial non-contrast-enhanced T2-weighted fast field echo magnetic resonance image (Philips) done on day two after the onset of severe headaches shows no haemosiderin deposition.
Figure 2.
(a)–(d) Three-dimensional rotational angiography of the right ICA shows the ICA fenestration with a dumbbell-shaped aneurysm surrounded by a weaker (*) and a stronger (#) branch of the fenestrated ICA. ICA: internal carotid artery; OA: ophthalmic artery; ACA: anterior cerebral artery; MCA: middle cerebral artery; Ay: aneurysm.
At the interdisciplinary neurovascular board, the microsurgical and interventional radiological treatment options were discussed. Interventional radiological care would only be possible by using flow diverter or stent-assisted coiling. However, it would have required the previous onset of dual platelet inhibition. Due to the unclear bleeding history, we considered that the aneurysm was not amenable to primary endovascular therapy. Therefore, we scheduled the craniotomy and clipping of the aneurysm.
Intraoperatively, after performing a pterional approach and anterior clinoidectomy, the fenestration and the aneurysm of the ICA were exposed as shown in Figures 3 and 4. The proximal bifurcation of the right ICA and the distal confluence were visualised. The stronger, medial carotid branch was partially behind the optic nerve and microsurgically inaccessible. The weaker laterally extending carotid branch was for the most part hidden behind the aneurysm. The distal confluence was accessible but showed oozing haemorrhage even at the most delicate manipulation. Ultimately, it was not possible to resolve whether the aneurysm was fed from both branches or from only one. We decided that the aneurysm was not amenable to primary clip occlusion due to its anatomical constellation and intraoperative high bleeding risk. Thus we performed a wrapping with the help of a muscle patch, which was cuffed around the aneurysm complex and fixed by sutures.
Figure 3.
(a) Intraoperative illustration of the aneurysm after performing an anterior clinoidectomy. (b) Demonstration of the aneurysm after injecting indocyanine green. PCA: processus clinoideus anterior; ICA: internal carotid artery; N.II: optic nerve; Ay: aneurysm.
Figure 4.
Schematic drawing of the aneurysm and the fenestration of the right carotid artery with the weaker (*) and stronger (#) branch of the fenestrated ICA after anterior clinoidectomy. PCA: processus clinoideus anterior; ICA: internal carotid artery; N.II: optic nerve; Ay: aneurysm.
Postoperatively, the patient recovered well from the operation without deficits. The headaches were also decreasing. After reconsidering the case at the interdisciplinary neurovascular board, we decided to realise the endovascular therapy. Therefore, the patient was loaded with acetylsalicylic acid (ASA) and clopidogrel. We performed a platelet function test (Multiplate). After a positive result, we scheduled the patient for stent-assisted coiling (34 days after wrapping). An experienced (more than 10 years of experience) neurointerventionalist performed the procedure. The patient was treated under general anaesthesia in the angio-suite at the Department of Radiology and Neuroradiology. After placing of a self-expanding nitinol stent (4.5 mm/21 mm) in the stronger branch of the ICA fenestration (Figure 5), the aneurysm was occluded by five coils (Target 360 soft 3 mm/9 cm; Target 360 standard 7 mm/20 cm; Target 360 standard 6 mm/20 cm; Target 360 standard 4 mm/10 cm; Target 360 soft 3 mm/8 cm). Figure 6 shows the complete obliteration of the aneurysm. After the successful intervention, the patient was discharged without neurological deficits. We recommended the patient to take ASA lifelong and clopidogrel for a further 6 months.
Figure 5.
(a) and (b) Sagittal view of digital subtraction angiography after placing of a self-expanding nitinol stent (4.5 mm/21 mm) in the stronger branch of the ICA fenestration. Arrows show the distal and proximal end of the stent. ICA: internal carotid artery; Ay: aneurysm.
Figure 6.
(a) Sagittal view of digital subtraction angiography (DSA) after placing the second coil in the aneurysm (arrows). (b) Sagittal and (c) coronal view of DSA after occluding the aneurysm (arrows) and the weaker branch of the fenestrated ICA with a total of five coils. ICA: internal carotid artery; OA: ophthalmic artery.
Discussion
The infraclinoidal localisation of vascular abnormalities, in contrast to the supraclinoidal position, points out anatomical challenges limited by neural, vascular and bony structures. In our case – the anterior clinoid process making it difficult to access the aneurysm overlaps the aneurysm proximately. The cavernous sinus and the ophthalmic artery are also limiting structures. The aneurysm is neighbouring directly the optic nerve and is limited laterally by the occulomotor nerve.
Tables 1 and 2 show the published cases of ruptured and unruptured aneurysms that occurred in the supraclinoidal ICA fenestration and their treatment modalities, respectively. Considering the cases in Table 1, three out of five patients were treated surgically; two with aneurysm wrapping, one with aneurysm clipping.12,13 We managed our case by surgical wrapping and stent-assisted coiling. Only one endovascular approach was noted in the published cases of ruptured aneurysm.8
Table 1.
Characteristics of published case reports with ruptured aneurysm of fenestrated ICA.
| No. | Author | Publication date | Age, years | Sex | Location | Part of ICA | Treatment |
|---|---|---|---|---|---|---|---|
| 1 | Yock et al. | 1984 | 41 | Female | Right ICA | Supraclinoid | Wrapping |
| 2 | Chen et al. | 2007 | 31 | Male | Bilateral ICA | Supraclinoid | Wrapping |
| 3 | Nakiri et al. Case 2 | 2011 | 44 | Male | Left ICA | Supraclinoid | Coiling |
| 4 | Dey et al. Case 2 | 2011 | 32 | Female | Left ICA | Supraclinoid | Coiling |
| 5 | Present case | 49 | Female | Right ICA | Infraclinoid | Wrapping/coiling |
ICA: internal carotid artery
Table 2.
Characteristics of published case reports with unruptured aneurysm of fenestrated ICA.
| No. | Author | Publication date | Age, years | Sex | Location | Part of ICA | Treatment |
|---|---|---|---|---|---|---|---|
| 1 | Ng et al. | 2006 | 34 | Female | Right ICA | Supraclinoid | Clipping/coiling |
| 2 | Onoda et al. | 2008 | 42 | Female | Left ICA | Supraclinoid | Wrapping |
| 3 | Plumb et al. | 2010 | 48 | Female | Left ICA | Supraclinoid | Clipping |
| 4 | Nakiri et al. Case 1 | 2011 | 47 | Female | Right ICA | Supraclinoid | Coiling |
| 5 | Dey et al. Case 1 | 2011 | 39 | Female | Right ICA | Supraclinoid | Clipping |
| 6 | Ischikawa et al. | 2011 | 47 | Female | Left ICA | Supraclinoid | Coiling |
| 7 | Banach et al. | 1993 | 37 | Female | Left ICA | Supraclinoid | Clipping |
| 8 | Seong-Ho Park et al. | 2012 | 44 | Male | Left ICA | Supraclinoid | Coiling |
ICA: internal carotid artery.
In Table 2, which presents all published cases without SAH associated with an aneurysm and ICA fenestration, there is a slight approximation of numbers. Four cases were exclusively treated surgically6,7,9,11 three interventionally1,8,10 and one case was treated by surgical clipping and endovascular occlusion.5
In the majority of cases with supraclinoidal fenestrations harbouring aneurysms, surgery was favoured as the first option regardless of whether the patients had SAH or not.1,5–13 Out of a total of 12 cases, seven underwent surgery,6,7,9,11–13 four underwent angiographic intervention,1,8,10 and in one case interventional as well as surgical treatment was performed.5 In summary, the few published cases do not allow us to conclude on a preferable treatment modality.
In the case of our patient, the decision of the interdisciplinary neurovascular board was led by the suspicion of SAH and the consecutive risk of re-bleeding after platelet inhibition. Coiling was classified as difficult due to the anatomical constellation. Providing the aneurysm with stents followed by coiling would have required a saturation of ASA and clopidogrel for several days. Despite morphological missing SAH detection, we assumed a symptomatic aneurysm in the typical clinical symptoms. In this case, dual platelet inhibition was contraindicated. Intraoperatively, the aneurysm was not clippable. The placement of fenestrated clips by the medial carotid branch would have led to a position of the clip locks directly on the optic nerve, and sacrifice of the lateral carotid branch. Placing clips into the fenestration could have caused rupture of the aneurysmal neck or severe stenosis of the ICA. Thus we decided to wrap the complex. Afterwards, from our point of view, dual platelet inhibition was justifiable, and finally the patient was treated well with stent-assisted coiling.
In the ex-post view, one could question whether surgery wrapping before interventional treatment was necessary and whether the proofs for SAH were clear enough to justify surgery. However, our worst case scenario was to face severe haemorrhage during interventional treatment and to know that complicated and time-consuming preparation is needed even to access the aneurysm complex.
Conclusion
Aneurysms of fenestrated ICAs are rare conditions mainly relating to the infraclinoid segment. In our case aneurysm clipping failed because of the anatomical conditions. However, wrapping to control possible re-bleeding and stent-assisted endovascular coiling finally led to successful occlusion of the aneurysm along with an excellent clinical outcome. We learned that the combination of surgical and interventional treatment could be considered an option in such complex cases.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Conflict of interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
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