A ruptured aneurysm at the distal end of the basilar artery fenestration associated with multiple fenestrations of the vertebrobasilar system: Case report

Fenestrations of intracranial arteries and associated aneurysms are rare. The significance of these fenestrations in relation to aneurysms remains unclear. We present four patients with fenestration-associated aneurysms and a comprehensive review of associations with aneurysms and other vascular lesions. A PubMed search of the literature was conducted from 1970–2012 reporting cases of intracranial aneurysms associated with arterial fenestration or duplications. Data were collected on patient presentation, sex, age, aneurysm and fenestration location, aneurysm treatment, and presence of other vascular lesions. We performed a retrospective review of four patients with intracranial fenestrations associated with aneurysms at our institution from 2012–2013. There were 59 cases of fenestrations and associated aneurysms in the literature. Aneurysms were reported as either arising from (n = 50) or adjacent to but distinct from (n = 13) fenestrations. The most common single fenestration location was at the basilar artery (n = 23, 36.5%); however the majority of fenestrations were in the carotid circulation (n = 34, 54.0%). The majority of patients with aneurysms and fenestrations at all locations except those at the anterior communicating artery (70.5%) presented with subarachnoid hemorrhage. Patients with aneurysms arising from a fenestration or adjacent to a fenestration presented with an additional intracranial vascular lesion in 38% and 31% of cases, respectively. The majority of all aneurysms were treated with microsurgical clipping. Aneurysms associated with cerebral arterial fenestrations are most commonly discovered after subarachnoid hemorrhage and are most often located in the carotid circulation. A high index of suspicion must be maintained for an associated vascular lesion if an intracranial fenestration is discovered.

Aneurysms associated with a fenestrated basilar artery are rare, and treatment strategies have yet to be established. A direct surgical approach to the basilar artery is challenging because the surrounding anatomy is complex. We retrospectively compared the clinical features and treatment outcomes of eight patients (seven female, one male) with aneurysms associated with a fenestrated basilar artery after clipping or coil embolisation and reviewed the literature. Of the eight aneurysms, four were ruptured; seven aneurysms were located at the proximal part of the basilar artery and one aneurysm was located at the middle of the basilar artery. Six aneurysms were surgically treated. Four aneurysms were embolised with Guglielmi detachable coils, two aneurysms were clipped via the transcondylar or temporopolar approach, and two aneurysms were not treated. All six surgically treated patients had good outcomes. We found that both coil embolisation and direct clipping to treat aneurysms associated with a fenestrated basilar artery have advantages and disadvantages. To obtain favourable outcomes, the selected treatment modality must consider the patient’s age and clinical condition, the aneurysm size and shape, the direction of the dome, the relationship with perforators, and the neurosurgeon’s expertise.

The cerebral vascular architecture is both unique and heterogeneous in its structure, organization, and function. For many years, it was believed that brain vasculature was dominated by nonanastomosing terminal or “end-arteries.” This was primarily based upon the observation of discrete distribution of brain infarcts after embolic occlusion of particular vessels. It was not until the detailed anatomy work of Pfeiffer in 1928 that the new concept of an almost-uninterrupted vascular network of brain vasculature was proposed. Since then, the cerebral vascular anatomy and embryology has been studied in great detail. Its full description is beyond the scope of this article, and our aim is to provide a brief overview of the development of cranial arterial anatomy, with special emphasis on commonly encountered anatomical variations that may have clinical implications. The failure to recognize these can lead to misdiagnosis as well as otherwise-preventable iatrogenic injuries and complications. We describe the proposed underlying embryologic processes, pathology and clinical implications of these variations, including aberrant internal carotid arteries, carotid agenesis and hypoplasia, azygous anterior cerebral arteries, arterial fenestrations, and persistent embryonic vessels.

Aneurysms associated with vertebrobasilar fenestrations are uncommon. We report on an unusual presentation of such aneurysm with a dedicated arterial pedicle, manifesting with significant intraventricular hemorrhage. Equally important, the aneurysm was managed in a multidisciplinary fashion, which, we think, greatly contributed to a good outcome.

A 55-year-old man presented in good condition after subarachnoid and massive intraventricular hemorrhage. The aneurysm location and the extent of intraventricular hemorrhage both presented concerns regarding treatment approach. The aneurysm was first treated with transarterial coil obliteration, and intraventricular tissue plasminogen activator (tPA) infusion was given, with rapid resolution of evolving hydrocephalus. The patient had an excellent outcome.

To our knowledge, this is the first report of a vertebrobasilar fenestration saccular aneurysm with a dedicated pedicle projecting toward the foramen of Magendie with significant intraventricular hemorrhage. In addition, this patient was successfully managed with endovascular obliteration and intraventricular tPA infusion.

BACKGROUND

Basilar artery fenestrations are most commonly located in the proximal basilar trunk close to the vertebrobasilar junction and may harbor saccular aneurysms. Surgical treatment of such aneurysms has been reported in several cases previously, despite the difficulty of the surgical approach. Endovascular treatment may provide a more convenient treatment alternative in such cases. This case is also interesting in that two discrete aneurysms arise from each limb of the fenestration.

CASE REPORT

A 20-year-old man presented with acute subarachnoid hemorrhage. He had two kissing aneurysms at the fenestrated proximal basilar artery as demonstrated by MRA and selective angiography. The two aneurysms were successfully treated with GDCs via the contralateral vertebral arteries. One-year control angiogram showed stable occlusion.

CONCLUSION

Aneurysms at the fenestrated basilar artery may be effectively treated with endovascular coil occlusion. The occurrence of multiplicity and the treatment alternatives are discussed, with relevant literature review.