- Department of Neurosurgery, David Geffen School of Medicine at UCLA, UCLA Medical Center, Los Angeles, CA, USA
- Department of Radiology, David Geffen School of Medicine at UCLA, UCLA Medical Center, Los Angeles, CA, USA
- Department of Radiology, Neurointerventional Radiology, David Geffen School of Medicine at UCLA, UCLA Medical Center, Los Angeles, CA, USA
Neil A. Martin
Department of Neurosurgery, David Geffen School of Medicine at UCLA, UCLA Medical Center, Los Angeles, CA, USA
DOI:10.4103/2152-7806.109811Copyright: © 2013 McLaughlin N This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: McLaughlin N, Villablanca PJ, Jahan R, Martin NA. An infundibulum of thalamoperforator arteries: Importance of angiographic images for appropriate diagnosis. Surg Neurol Int 30-Mar-2013;4:44
How to cite this URL: McLaughlin N, Villablanca PJ, Jahan R, Martin NA. An infundibulum of thalamoperforator arteries: Importance of angiographic images for appropriate diagnosis. Surg Neurol Int 30-Mar-2013;4:44. Available from: http://sni.wpengine.com/surgicalint_articles/an-infundibulum-of-thalamoperforator-arteries-importance-of-angiographic-images-for-appropriate-diagnosis/
Background:The identification of infundibula on noninvasive imaging modalities may be challenging. Because these lesions have generally been viewed as nonpathological, distinguishing them from small or micro-aneurysms is important.
Case Description:A 39-year-old male was diagnosed with recurrence of typical orgasmic headache. An outpoutching arising from the distal part of the right P1 at the take-off of thalamoperforator arteries was visualized on noninvasive investigations. The patient was referred to neurosurgery for surgical management of a right P1 aneurysm. Its unusual location and morphology led to be suspicious of an infundibular dilatation. Catheter angiography with 2D projections and 3D rotational reconstruction revealed an infundibulum at the common origin of two thalamoperforators, giving rise to a double-peaked shape, mimicking a true aneurysm, rather than the more characteristic conical shape of an infundibulum.
Conclusion:Although noninvasive modalities may identify typical infundibula, the catheter angiogram with 2D projections was critical to establishing the diagnosis. The 3D rotational reconstruction enabled a straightforward understanding of the 3D vascular anatomy. This pyramidal variant of infundibular dilatation should be included in the differential diagnosis of a wide-based nonsaccular arterial contour deformities located in an area of multiple perforators.
Keywords: Aneurysm, angiography, dissecting aneurysm, infundibulum, perforator, posterior cerebral artery
The identification of infundibula on noninvasive imaging modalities may be challenging. Although computed tomography angiography (CTA) and magnetic resonance angiography (MRA) have become the primary imaging screening techniques for detection of possible aneurysms, the limitations of these modalities in identifying outpouchings and rendering detailed assessment of their relationship with branches/perforators has been recognized. Because infundibula have generally been viewed as nonpathological, distinguishing them from small or micro-aneurysms is important. We present a unique case of an infundibulum at the common origin of two thalamoperforators, giving rise to a double-peaked shape that mimics a true aneurysm, discuss the differential diagnosis, and emphasize the importance of catheter angiography for appropriate diagnosis and management.
A 39-year-old male was referred for management of a possible right P1 aneurysm. The patient was in good general health and his family history was negative for any cerebrovascular pathology. He recently experienced recurrence of his typical coital headaches, which had been diagnosed in his twenties. For completeness, the referring physician requested brain imaging.
The initial head computed tomography (CT) scan performed within 48 h of his last headache failed to show acute subarachnoid hemorrhage. The CTA revealed a rounded bulge arising from the right distal P1 segment of the right posterior cerebral artery (PCA) [Figure
Left vertebral artery injection, (a) 2D angiography and, (b) 3D rotational angiography and left common carotid artery injection (c) 2D angiography and, (d) 3D rotational angiography. a and b show the double peaked shape infundibulum (white arrow) arising proximal to the junction of the right PcomA and PCA. (c and d) the two infundibuli (white asterixis) at the origins of the left AchoA and left PcomA
Infundibulum: Definition and variation
By definition, an infundibulum is a conical, triangular, or funnel-shaped dilatation of the origin of a major branch of the internal carotid artery (ICA).[
Therefore, in the context of a wide-based nonsaccular bulge located in an area of multiple perforators, the differential should include not only an atypical aneurysm or a dissecting aneurysm, but also a variant infundibular dilatation. Although we have encountered infundibular dilatations at the origin of the lenticulostriate arteries, this is the first observation and, to the authors’ knowledge, the first description in the literature of an infundilum at the origin of thalamoperforators.
Identification of infundibular dilatations
Infundibular dilatations were initially described on cerebral angiograms by Saltzman in 1959.[
Infundibula have been identified in 7-25% of catheter angiograms.[
Clinical significance of infundibula
The clinical significance of a particular infundibulum is impossible to predict solely by imaging. Hassler and Saltzman have described several cases of PcomA infundibula, which presented defects in the media and splitting of the internal elastic lamina, histological changes similar to those found in aneurysms. However, none of the patients of their original series had presented with subarachnoid hemorrhage. Although for most clinicians the typical infundibular dilatations have minimal pathogenic significance and risks, some authors consider them to be pre-aneurysmal lesions.[
To date, there is no consensus regarding if, when, how, and for how long imaging follow-up should be coordinated in the presence of a well characterized infundibulum or even small asymptomatic aneurysms.[
In summary, this is the first description of an infundibulum at the common origin of two thalamoperforators, giving rise to a double-peaked shape that mimics a true aneurysm, rather than the more characteristic conical shape of an infundibulum. This variant of infundibular dilatation should be included in the differential diagnosis of a wide-based nonsaccular arterial contour deformities located in an area of multiple perforators. Although noninvasive modalities may identify typical infundibula, the catheter angiogram with 2D projections may be critical to establish the diagnosis in some patients, with the 3D rotational reconstruction allowing a straightforward understanding of the 3D vascular anatomy.
This research was supported by the Casa Colina-Neil Martin Fellowship Program at UCLA.
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