Top-basilar aneurysm

Clinical History

A patient presented with a history of left side wakeness deficit. The patient underwent a carotid color doppler ultrasound as first line examination that demonstrated a moderate stenosis of the proximal internal right carotid. For comprehensive pre-operative work-up, the patient underwent CT angiography of supra-aortic and intracranic vessels.

Imaging Findings

The patient presented with a history of left side wakeness deficit. The patient underwent carotid color doppler ultrasound as first line examination that demonstrated a moderate stenosis of the proximal internal right carotid. For comprehensive pre-operative work-up, the patient underwent CT angiography of supra-aortic and intracranic vessels. The results of CTA confirmed the moderate stenosis of the right carotid. During the same examination, a top-basilar artery aneurysm was seen as an incidental finding measuring 8.9 x 9.6 mm as displayed on axial (Fig. 1) and coronal images (Fig. 2). Image post-processing was performed and volume-rendering as well as MPR 3D (Fig. 3a and 3b) reconstructions were generated. Volume rendering reconstructions showed an aneurysmal neck, the diameter of which was 34 mm (Fig. 4).

Discussion

An intracranial aneurysm is an abnormal outward bulging of one of the arteries in the brain. Brain aneurysms are often discovered when they rupture, causing a subarachnoid hemorrhage. Other ruptured cerebral aneurysm symptoms include nausea and vomiting, stiff neck or neck pain, blurred vision or double vision, pain above and behind the eye, dilated pupils, sensitivity to light, and loss of sensation. Before an aneurysm ruptures, the patients often experience no symptoms of brain aneurysms. In about 40% of the cases, people with unruptured aneurysms will experience some or all of the following cerebral aneurysm symptoms: peripheral vision deficits, thinking or processing problems, speech complications, perceptual problems, sudden changes in behavior, loss of balance and coordination, decreased concentration, short-term memory difficulty, and fatigue. To determine the exact location, size and shape of an aneurysm (ruptured or unruptured), radiologists generally use either cerebral angiography or tomographic angiography. Conventional angiography, generally selective intra-arterial digital subtraction angiography (DSA), has been the criterion standard for the detection and characterization of intracranial aneurysms. The primary advantage of DSA over other imaging modalities is the high resolution achieved by most systems, generally providing 0.3-mm resolution. This high resolution translates into relatively high sensitivity and specificity for the detection of aneurysm, with a reported false negative rate of 5%–10%. Helical CT angiography (CTA) is a comparatively new noninvasive volumetric imaging technique. Images can be safely obtained by a trained technologist without the need for arterial puncture or catheter manipulation. CTA is not associated with significant patient risks. Furthermore, CTA image acquisition requires an imaging time of ≤1 minute. Once acquired, CTA data can be viewed from unlimited projections in both 2D and 3D modes, facilitating the task of aneurysm detection. In some centers, CTA has been reported to be the only study performed before surgery in a significant number of cases and has been shown to reveal aneurysms when DSA results are negative. The main goals of treatment once an aneurysm has ruptured are to stop the bleeding and potential permanent damage to the brain and to reduce the risk of recurrence. Unruptured brain aneurysms are sometimes treated to prevent rupture.

Differential Diagnosis List

Final Diagnosis

Top-basilar aneurysm.

URL:	https://www.eurorad.org/case/3325
DOI:	10.1594/EURORAD/CASE.3325
ISSN:	1563-4086