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Neuroradiology Case of the Week
Case 318
Adam J. Weller, MSIV
Clinical
Presentation: Patient is a 20-month-old female found unresponsive.
Imaging Findings: CT head: A large, enhancing lesion measuring approximately 34 x 16mm is noted in the right temporal and frontal lobes sitting over the course of the right middle cerebral artery. The attenuation of the mass is similar to that of the vessels. There is a surrounded heterogeneous nonenhancing area with evidence of calcifications. These findings are suggestive of a partially thrombosed large aneurysm arising from the right middle cerebral artery with calcification and acute hemorrhage. The aneurysm is seen causing mass effect over the right lateral and third ventricle with midline shift towards left side.
CT angio: A large aneurysm is seen in the M2 portion of the right middle cerebral artery.
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Figure 1: Axial head CT - non-contrast. Large heterogeneous mass can be seen in the right temporal and frontal lobes. the mass measures 34 X 16 mm. Calcifications can be seen in the lesion.
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| Figure 2. Axial head CT with contrast. Enhancing portion of lesion can be seen and is surrounded by a heterogeneous non-enhancing area with calcifications. These findings indicate a partially thrombosed large aneurysm with acute hemorrhage. |
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Figure 3: Axial CT head angiogram. Large aneurysm is seen in the M2 portion of the right middle cerebral artery. |
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| Figure 4. Sagittal CT head angiogram. Visualization of heterogeneous, enhancing mass extending posteriorly. |
Diagnosis: Giant aneurysm
Discussion: Intracranial aneurysms are known to be rather rare in the pediatric population. Out of all reported intracranial aneurysms it is reported that 0.6% to 5% are in the pediatric population (up to 18 years of age). It has also been noticed that the younger the population you consider the lower the incidence gets. Pediatric intracranial aneurysms are known to be associated with many causes (Table 1). However, there are no known underlying systemic disorders found in most cases.
As in this case, the occurrence of “giant” aneurysm (greater that 2.5 cm in diameter) has been found to be much higher in the pediatric population 21% as opposed to the adult population (7%). Giant aneurysms are thought to be associated with a much worse morbidity and mortality, however is found to be lower in children presumably due to less vasospasm, and underlying atherosclerotic disease. They also tend to present at much younger ages which may to contribute to the increased incidence in the young pediatric population.
The location of aneurysms in pediatric population also differs from adults. It has been reported that up to 33% of pediatric aneurysms are located in the posterior circulation as compared with 5-10% in adults (Table 2). It has been noted that this preference is even more pronounced in patients less than 2 years of age. Giant aneurysms have shown this preference for posterior circulation in adults as well as children.
The typical clinical presentation of pediatric aneurysms also differs from the adult presentation. In Children, male predominance is seen (male to female ratio is 1:2.2), unlike the female predominance seen in adults. In older kids the typical presentation is that of subarachnoid hemorrhage: sudden onset of headache, vomiting, obtundation and coma. Aneurysms in patients under the age of 5 are more likely to be asymptomatic or show signs of a space occupying lesion, especially in patients with a giant aneurysm. Neonates and infants can also present with nonspecific signs such as irritability, seizures, drowsiness, or emesis. The pediatric population also shows a higher incidence of mycotic and traumatic aneurysms. Mycotic aneurysms have been shown to usually be associated with bacterial endocarditis, and traumatic aneurysms are technically not aneurysms at all and better classified as a pseudoaneurysm as they do not have an endothelial wall.
Table 1: Disorders Associated with Pediatric Intracranial Aneurysms |
Aortic coarctation |
Polycystic kidney disease |
Fibromuscular dysplasia |
Tuberous Sclerosis |
Arteriovenous malformation |
Vascular anomalies |
Cardiac Myxoma |
Cerebral tumors |
Ehlers-Danlos Syndrome |
Marfan Syndrome |
Irradiation |
Moyamoya syndrome |
Human immunodeficiency virus |
Syphilis |
Thalassemia |
G-6-P-D deficiency |
Sickle cell anemia |
Pseudoxanthoma elasticum |
Taken from Aryan HE, et al. [2] |
Table 2: Distribution of Pediatric and Adult Aneurysms. |
Location |
Child (%) |
Adult (%) |
Anterior Circulation |
79 |
93 |
Posterior Circulation |
21.2 |
7 |
Taken from Aryan HE, et al. [2] |
References:
- Barkovich J. Pediatric Neuroimaging, 3rd Edition, Philadelphia, Lippincott Williams & Wilkins 2000, pg 415-421.
- Aryan HE, Giannotta SL, Fukushima T, Park MS, Ozgur BM, Levy ML. Aneurysms in children: review of 15 years experience. J Clin Neurosci. 2006 Feb;13(2):188-92. [Medline]
- Sharma BS, Sinha S, Mehta VS, Suri A, Gupta A, Mahapatra AK. Pediatric intracranial aneurysms-clinical characteristics and outcome of surgical treatment. Childs Nerv Syst. 2007 Mar;23(3):327-33. [Medline]
- Allison JW, Davis PC, Sato Y, James CA, Haque SS, Angtuaco EJ, Glasier CM. Intracranial aneurysms in infants and children. Pediatr Radiol. 1998 Apr;28(4):223-9. [Medline]
- Sungarian A, Rogg J, Duncan JA 3rd. Pediatric intracranial aneurysm: a diagnostic dilemma solved with contrast-enhanced MR imaging. AJNR Am J Neuroradiol. 2003 Mar;24(3):370-2. [Medline]
- Buis DR, van Ouwerkerk WJ, Takahata H, Vandertop WP. Intracranial aneurysms in children under 1 year of age: a systematic review of the literature. Childs Nerv Syst. 2006 Nov;22(11):1395-409. [Medline]
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