Basilar artery fenestration aneurysm and carotid occlusion
Basilar artery fenestration aneurysm and carotid occlusion SLICE Next Frontiers 2023
· Basilar artery fenestration aneurysm:
Basilar fenestration is a congenital anomaly of the basilar artery. Actually, is the most common congenital anomaly and is the second most common site of intracranial artery fenestration (first one is AcomA)1,2. Definition of fenestration is a segment of the vessel with the lumen divided into two separate channels that fuse during their course, restoring a primary vessel3. Basilar artery fenestration is reported in 0.6% of DSA and 5% of autopsy3. It can occur anywhere along the course of the basilar artery, but it is most frequent in the proximal basilar trunk, close to the junction of the vertebral arteries4.
To understand this alteration, we need to return to embryology. Basilar artery is formed during the second to fourth stages of embryonic development by the fusion of two primitive longitudinal neural arteries5. In the early stages of fusion these arteries are connected by several bridging areas; further fusion occurs to form the basilar artery. If these areas of irregularity persist, they result in fenestration6. Aneurysms associated with a fenestrated basilar artery are very uncommon; their incidence is reported to be 0.33 % of all intracranial aneurysms7. During SLICE 2023 we can see a great discussion about the treatment of an aneurysm in a fenestration of the basilar artery. As there is no consensus on the subject, we can see different strategies to treat the same aneurysm being presented by professors: Adnan Siddiqui, René Chapot, Michel Piotin, Vincent Constalat, Vitor Mendes Pereira.
· Carotid occlusion:
There are some treatments in which the stents may not be very well adapted to the artery. One of the discussions is whether we should perform an occlusion test in internal carotid artery aneurysms to assess the possibility, in some cases, of occlusion of this vessel. The protocol for therapeutic ICA occlusion has been described previously in literature8,9. Reconstructive techniques may not be sufficient for the treatment of some aneurysms. Furthermore, some stents may not adapt as well to the arterial wall. As a result, some different techniques are
needed to open the same as a coronary balloon to perform angiolpasty and better opening of the stent, such as the use of coronary stents.
Why consider occluding a carotid artery? One of the explanations, if this therapeutic possibility is possible, is that the navigability of coronary stents is not so simple to pass through the carotid siphon. Some strategies can be used: using a intermediate catheter in a very high position and using coronary stents with a smaller diameter and length possible so that navigability is better. Sometimes carotid occlusion can be less complex than the ones mentioned above.
There are some data showing that therapeutic carotid artery occlusion after an- giographic testing, the risk of permanent neurologic complications was extremely low10.
· Further reading:
1) Trivelato, F., Abud, D., Nakiri, G. et al. Basilar Artery Fenestration Aneurysms: Endovascular Treatment Strategies Based on 3D Morphology. Clin Neuroradiol 26, 73–79 (2016).
2) Takahashi M, Tamakawa Y, Kishikawa T, KowadaM(1973) Fenestration of the basilar artery. Radiology 109: 79–82.
3) Polguj M, Podgórski M, Jędrzejewski K, Topol M, Majos A. Fenestration and duplication of the vertebral artery: the anatomical and clinical points of view. Clin Anat. 2013 Nov;26(8):933-43..
4) Nakasu Y, Nakasu S, Kidooka M, Handa J (1982) Aneurysm at the fenestration of the basilar artery. Case report. Arch Jpn Chir 51: 344–348.
5) Padget DH (1968) The development of the cranial arteries in the human embryo.Contrib Embryol 32: 205–261
6) Tasker AD, Byrne JV. Basilar artery fenestration in association with aneurysms of the posterior cerebral circulation. Neuroradiology. 1997 Mar;39(3):18 9.
7) Tanaka S, Tokimura H, Makiuchi T, Nagayama T, Takasaki K, Tomosugi T, Hirahara K, Yamahata H, Campos F, Nishizawa T, Arita K. Clinical presentation and treatment of aneurysms associated with basilar artery fenestration. J Clin Neurosci.2012;19(3):394–401.
8) van Rooij WJ, Sluzewski M, Slob MJ, et al. Predictive value of angio- graphic testing for tolerance to therapeutic occlusion of the carotid artery. AJNR Am J Neuroradiol 2005;1:175–78
9) van Rooij WJ, Sluzewski M, Metz NH, et al. Carotid balloon occlu- sion for large and giant aneurysms: evaluation of a new test occlusion protocol. Neurosurgery 2000;47:116 –21
10) R.S. Bechan, C.B. Majoie, M.E. Sprengers, J.P. Peluso, M. Sluzewski and W.J. van Rooij American Journal of Neuroradiology January 2016, 37 (1)125-129
