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Neuroradiology Case of the Week
Case 328
Annie Wang, MSIV and P-L Westesson, MD, PhD, DDS
Clinical
Presentation: Patient is a 2-year-old Somalian child who was in good health until the day of admission when her primary caretaker noted she was sleepier than usual. At the time of admission, she was noted to have a dysconjugate gaze and be unresponsive.
Imaging Findings: A large mass with calcification, acute hemorrhage, and mass effect over the right lateral ventricle and surrounding cerebral parenchyma are noted in the right temporalfrontal region. This most likely represents a partially thrombosed aneurysm in the right middle cerebral artery with acute hemorrhage.
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| Figure 1:
Axial view of CT of the head without contrast demonstrates a large, heterogeneous, well-defined mass lesion in the right temporalfrontal regions with evidence of calcification and areas of acute hemorrhage. Lesion is surrounded by edema in the posteromedial region. There is mass effect noted in the right lateral and third ventricle and right mid-brain region. |
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Figure 2: CT angiography of the head shows a large, partially thrombosed aneurysm noted in the M2 portion of the right middle cerebral artery with acute hemorrhage and mass effect causing midline shift of 6mm towards the left.
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Figure 3:
MPR 3-D reconstruction confirmed the aneurysm location in the M2 portion of the right middle cerebral artery. The remaining major intracranial arteries appear normal.
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| Figure 4: Axial view of CT of the head without contrast shows interval evacuation of the hematoma in the right frontotemporal region with successful clipping in the right MCA aneurysm. |
Diagnosis: Ruptured MCA aneurysm
Discussion: Intracranial aneurysms are rare in the pediatric population. They have a bimodal distribution. In early childhood (<6 years old), there is a peak in the first 6 months with the majority of cases seen in the first 2 years. A second peak is seen in children from the age of 8 years to adolescence. Aneurysms in childhood usually affect the middle and posterior cerebral artery circulation and are associated with collagen vascular diseases and connective tissue disorders. These aneurysms are frequently large in size and have a higher incidence of subarachnoid hemorrhage (SAH) compared to the adult population. However, the incidence of aneurysmal rupture in children is higher than in adults ranging 52-65%.
There are a number of probable causes for the development of aneurysms. Early damage from hypertension, birth injury, trauma, and in utero insults are considered to play a major role. Other causes maybe attributed to intrinsic defects that may cause variable wall dysfunction producing transient or permanent failure to repair subsequent insults or to endothelial defects in one or two embryonic segments of the neural crest or mesoderm resulting in dysfunctional vessel wall remodeling. Aneurysms in childhood are frequently seen with spontaneous occurrences, previous cranial irradiation, sickle cell disease, congenital heart disease, arteriovenous malformations, fibromuscular dysplasia, tuberous sclerosis, Von-Hippel-Lindau disease, and connective tissue disorders.
In familial cases, there is a correlation between the locations of aneurysms in relatives, which indicates a genetic role in formation of aneurysms. Screening of high-risk children with familial SAH can be achieved using MR angiography or CT angiogram. It has been postulated that a deficiency of type III collagen causing fragmentation of the internal elastic lamina or a congenital defect in the muscularis layer of the media may play a role in familiar cases.
Aneurysms in pediatric patients are typically symptomatic at the time of diagnosis. Children present with sudden onset headache, vomiting, deterioration in consciousness, seizures, coma, paresis, cranial nerve palsies, fever, and meningismus. Giant aneurysms occur with mass symptoms, hydrocephalus, or cranial nerve palsies.
Pediatric patients require specialized and innovative procedures to obliterate the lesions. Therapeutic techniques include combinations of clip ligation, entrapment in giant lesions, tandem clipping, angioplastic clipping, aneurysmectomy, microsvascular anastomosis and bypass, direct excision with reanastomosis, ligation of the parent artery with tourniquet, direct ligation of the cervical carotid or vertebral arteries, extracranial-intracranial bypass, and direct excision without bypass. The role of endovascular therapy needs further evaluation. Children are able to tolerate vascular occlusion better due to the larger collateral vasculature and inherent plasticity of the brain compared to adults. Thus, the clinical outcome after SAH from a cerebral aneurysm is better than adults because of the low incidence of subsequent clinical vasospasm and cerebral ischemia. In a cohort study of 248 cases of ruptured aneurysm in children, 59% had excellent or normal results, 15% good results with minor deficits and 10% poor results with significant deficits.
References:
- Lasjaunias P, Wuppalapati S, Alvarez H, Rodesch G, Ozanne A. Intracranial aneurysms in children aged under 15 years: review of 59 consecutive children with 75 aneurysms. Childs Nerv Syst. 2005 Jun;21(6):437-50. [Medline]
- Proust F, Toussaint P, Garniéri J, et al. Pediatric cerebral aneurysms. J Neurosurg. 2001 May;94(5):733-9. [Medline]
- Herman JM, Rekate HL, Spetzler RF. Pediatric intracranial aneurysms: simple and complex cases. Pediatr Neurosurg. 1991-1992;17(2):66-72. [Medline]
- ter Berg HW, Bijlsma JB, Willemse J. Familial occurrence of intracranial aneurysms in childhood: a case report and review of the literature. Neuropediatrics. 1987 Nov;18(4):227-30. [Medline]
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