Keywords
intracranial aneurism - subarachnoid hemorrhage - cerebral angiography - fenestration
Palavras-chave
aneurisma intracraniano - hemorragia subaracnoide - angiografia cerebral - fenestração
Introduction
Fenestration of the basilar artery is presented in 0.6% to 2.3% of angiographies and
in ∼ 1–5% of autopsies.[1]
[2] It can occur anywhere along the basilar artery, but it is more common near the vertebrobasilar
junction. Saccular aneurysms of the vertebrobasilar junction are rare, but when present,
they are often associated with fenestration of the basilar artery.[1] Such variation occurs due to failure of fusion of the longitudinal neural arteries
in the embryonic period. The complex anatomy of the region makes endovascular treatment
the first choice in most cases. The present study aims to report the case of a patient
with aneurysm associated with fenestration of the basilar artery; his treatment and
follow-up= took place at a university hospital in São Paulo. The study also aims to
make a brief review on the topic.
Case Report
A 47-years-old man was admitted to the emergency unit of our hospital presenting with
headache, diplopia, neck pain and mental confusion ongoing for 3 days. The patient
was transferred from another service with a CT scan showing subarachnoid hemorrhage
(Fisher III) associated with hydrocephalus ([Fig. 1]).
Fig. 1 CT scan with subarachnoid hemorrhage (SAH) (Fisher III) and hydrocephalus.
At admission, the patient had stable vital signs, he was conscious and oriented, his
Glasgow coma scale (ECG) score was 15, and he did not present any motor or sensitive
deficit, no pupillary alteration, but had palsy of the left sixth cranial nerve and
Hunt- Hess grade III.
The patient was submitted to implantation of a ventricular-peritoneal shunt on the
same day of the admission and referred to the ICU without neurological deterioration.
A diagnostic angiography was performed with 3D reconstruction ([Fig. 2]), which showed evidence of fenestration of the basilar artery associated with aneurysm
in the right vertebrobasilar portion. An aneurysm coil embolization was performed
([Fig. 3]) without complications.
Fig. 2 3D-angiography showing aneurysm of the fenestrated basilar artery.
Fig. 3 Post-embolization arteriography with coils.
The patient was discharged 19 days later, maintaining diplopia and paralysis of the
left sixth cranial nerve, but without any other complaints or neurological symptoms.
Discussion
The basilar site is the second most common site of intracranial fenestration, after
the anterior communicating artery.[3] Fenestration of the basilar artery is a recognized vascular variation with dual
endothelium-lined vascular lumens, which is usually caused by a failure of fusion
of the paired longitudinal neural arteries during the fifth week of embryonic life.[1]
[2] The elastin defect in the tunica media combined with a pro-inflammatory state, weakening
the arterial wall at the distal and proximal edges of the fenestration and associated
with the alteration in the blood flow hemodynamics, are responsible for the development
of an aneurysm at the vertebrobasilar fenestrated junction.[4]
[5]
[6]
[7]
The location of these aneurysms is proximal to the brainstem, and the wide varieties
of the fenestrations complex and the presence of perforator vessels make the microsurgical
approach extremely dificcult.[1]
[2]
[8]
[9]
[10] An endovascular-based approach is becoming the first-line treatment, and meticulous
preprocedural planning is extremely important to study the exact anatomy of the aneurysm-fenestration
complex to determine the most appropriate endovascular therapeutic technique, Therefore,
the three-dimensional rotational angiography (3DRA) is an extremely helpful tool to
plan the endovascular treatment.[11]
Kai et al proposed two types of classification. Type A has a bridging artery between
the distal V4 portions of both vertebral arteries. The resulting fenestration showed
a somewhat triangular shape. Type B does not have a bridging artery and it is a somewhat
elliptical fenestration.[9] With the improvement of the 3-dimensional angiographic technology and of the endovascular
technique, Trivelato et al proposed a new classification based on the aneurysm neck
size and on the base of implantation in the proximal bifurcation of the fenestration,
which allowed for therapeutic planning by selecting the most adequate modality of
endovascular technique. The four types are described as follows: 1A: narrow neck,
symmetric at the bifurcation. 1B: narrow neck, spares one loop. 2A: wide neck, involves
both loops. 2B: wide neck, spares one loop.[2]
Several endovascular techniques are described, including simple coiling, balloon remodeling
technique, stent-assisted coiling, liquid embolic agents and flow diversion devices.
The literature shows that the majority of the fenestrated basilar artery aneurysms
was treated with simple coiling (78.2%), even those with wide necks. This could be
explained because many patients were treated before the development of the balloon
remodeling and the stent-assisted coiling techniques.[2]
[3]
T case reported shows an aneurysm of the fenestrated proximal basilar artery, type
B, as per Kai et al/type 1B as per Trivelato et al, treated by endovascular technique
using simple coil with a good angiographic and clinical outcome.
Conclusion
Fenestrated basilar artery aneurysms are rare and complex vascular diseases. Endovascular
treatment is the first option due to the intricate posterior fossa anatomy that is
a challenge for the open surgical treatment. With the advent of the 3D angiography,
a range of endovascular modalities emerged that led to the individualization of the
treatment of aneurysms showing promising results.
