|Ahead of print
Spontaneous thrombosis and stabilization of a dissecting PCA aneurysm in a child
Vikas Bhatia1, Arushi Gahlot Saini2, Rajeev Chauhan3
1 Department of Radio-diagnosis and Imaging, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
3 Anaesthesia and Intensive care, Postgraduate Institute of Medical Education and Research, Chandigarh, India
|Date of Submission||10-Sep-2020|
|Date of Decision||22-Oct-2020|
|Date of Acceptance||22-Nov-2020|
|Date of Web Publication||19-Jul-2021|
Department of Radio-diagnosis and Imaging, Postgraduate Institute of Medical Education and Research, Chandigarh.
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Spontaneously dissecting posterior cerebral artery (PCA) aneurysm in the pediatric age group is a rare entity. We discuss a child with a resolution of the aneurysm due to spontaneous thrombosis in the PCA.
Keywords: Dissecting aneurysm, PCA, thrombosis
| Introduction|| |
Pediatric intracranial aneurysms are rare and constitute 2–6% of all aneurysms. These are characterized by a male preponderance, predilection for the carotid artery bifurcation and posterior circulation, a higher incidence of large aneurysms, and a higher incidence of spontaneous thrombosis as compared with adults. Most pediatric aneurysms have predisposing factors such as infection, tumor, dissection, or trauma., The PCA aneurysms are uncommon and are seen in 0.8–1.4% of all aneurysms. Only one-tenth of these aneurysms are seen in the pediatric population. Arterial dissection is the most frequent cause of stroke in the posterior circulation in children. An intracranial dissection is seen in nearly 4% cases and is commonly related to preceding head trauma. PCA aneurysm with spontaneous intracranial dissection is anecdotally reported in children.,, We discuss a case with spontaneous thrombosis of such an aneurysm and its probable mechanism.
| Case|| |
A seven-year-old girl presented with an acute, severe headache for the past four days, which was associated with intermittent, projectile vomiting. There was no alteration in sensorium, visual disturbance, seizures, fever, neck stiffness, behavioral changes, photophobia, focal motor deficit, cranial nerve palsy, or diplopia. Past and family history was unremarkable. Her general and detailed neurological examination was normal. A clinical diagnosis of an acute, severe secondary headache secondary to an underlying arteriovenous malformation or aneurysm was considered. A noncontrast computed tomography scan showed a small bleed in the right perimesencephalic cistern. Diagnostic cerebral angiography showed a contrast-filled outpouching [Figure 1]A with irregular walls [Figure 1]B and proximal small segmental stenosis, at the right PCA-P3 segment. This confirmed the diagnosis of a dissecting aneurysm in the PCA. The patient was taken up for endovascular PCA occlusion after 72h, and selective right vertebral artery injection was administered. There was nonfilling of the aneurysm and the right PCA distal to the neck of the aneurysm [Figure 2]. A probable spontaneous thrombosis of the aneurysm and PCA was considered, and the patient was managed conservatively. She remained well in follow-up till one year.
|Figure 1: (A,B): Diagnostic right vertebral artery angiogram antero-posterior (A) and lateral (B) projections. There is evidence of right PCA aneurysm (white arrow heads), having irregular and proximal segmental narrowing at right PCA-P3, suggestive of dissecting aneurysm. (Left PCA had fetal origin)|
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|Figure 2: (A,B): Diagnostic right vertebral artery angiogram antero-posterior (A) and lateral (B) projections three days later. There is non-opacification of the aneurysm (black arrow heads), suggestive of spontaneous thrombosis.|
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| Discussion|| |
Intracranial arterial dissection is difficult to diagnose on routine imaging. The angiographic appearance of an aneurysm with the parent vessel stenosis, and stagnation of the contrast is the hallmark of a dissecting aneurysm. Head trauma is the leading cause of intracranial dissecting aneurysms in children, and a spontaneous dissection is unusual., The natural history of intracranial dissections is not exactly clear. These may remain stable and progressively decrease in size, thrombose, or catastrophically lead to massive bleeds and death. Spontaneous thrombosis is reported in 1–2% of pediatric aneurysms. It is seen in upto 38% cases of large or giant aneurysms and is usually seen with associated parent vessel thrombosis. The proposed mechanisms include a high aneurysm sac volume to neck size ratio, presence of proximal parent artery stenosis, progression of dissection leading to proximal artery occlusion, or enlarging aneurysm compression over parent artery., The role of contrast media used for diagnostic angiography has also been proposed, possibly due to activation of coagulation or the thrombosis mechanism., In our case, possibly the high sac to neck ratio and the presence of low intra-aneurysmal flow due to proximal stenosis or progression of dissection may, in isolation or together, have caused spontaneous thrombosis of the aneurysm and the parent artery distal to the aneurysm. Thus, endovascular management in the form of PCA occlusion was not carried out and spontaneous occlusion of the PCA did not result in any neurological deficit. This was most likely due to gradual thrombosis leading to the development of collateral flow to the involved PCA territory. A review of prior large studies showing spontaneous thrombosis of pediatric dissecting aneurysms is shown in [Table 1],,,,. Neurological deficit ranging from 0% to 17% has been previously reported for PCA occlusion.
|Table 1: Studies with pediatric cases showing spontaneous thrombosis of dissecting aneurysms.,,,,|
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| Conclusion|| |
Spontaneous arterial dissecting aneurysms in posterior circulation are uncommon. These have a dynamic natural history with variable and unpredictable outcomes. Spontaneous thrombosis of aneurysms has been seen; however, this outcome is highly unpredictable and, thus, requires a close interval follow-up and early management.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]