Evolution of a chronic dissecting aneurysm on magnetic resonance imaging in a pediatric patient

Abstract

<jats:p>Clinical and imaging manifestations of the so-called partially thrombosed aneurysm (PTA) are different from those of the classic intracranial saccular aneurysm. Given some of their peculiar imaging features, it had been hypothesized that some PTAs occur due to repeated intramural hemorrhages. The authors present a case of PTA that evolved from an acute dissecting aneurysm as shown by serial imaging. A previously healthy 5-year-old boy had a sudden onset of left hemiparesis. Initial MRI sequences showed a perforating vessel infarction in the right basal ganglia area secondary to an acute distal middle cerebral artery (MCA) dissection as demonstrated on conventional angiography. Conservative management with close observation of this dissection was chosen, and serial MRI studies revealed layering of blood of various ages within the wall of an aneurysmal outpouching of the MCA, thereby leading to the imaging appearance of a PTA. The findings in this case indicate that some PTAs may be caused by repeated or chronic dissections, with blood entering the wall through an endothelial defect. Understanding the pathological mechanism underlying the formation of these aneurysms will help inform appropriate treatment strategies.</jats:p>

Evolution of a large intracranial artery dissection on multimodal neuroimaging with spontaneous healing

“…On MRI, the intramural hematoma, as the pathognomonic feature of dissection disease [6,7], is considered to stem from two different possible pathological processes: hemorrhage of the vasa vasorum within the vessel wall or hemorrhage of the incompletely healed acute dissection with intimal tearing [8]. Furthermore, Krings et al thought that the angiographic appearance of stenosis is related to the intramural hemorrhage compressing the true vessel [5].…”

State-of-art in surgical treatment of dissecting posterior circulation intracranial aneurysms

“…A diversion of circulating blood into the weakened arterial wall may come from (a) a tear in the media due to rupture of the vasa vasorum [51] or new vessels formed in response to pathological process, such as atherosclerosis [124]; (b) the intimal surface causing mainly compression of the lumen by blood accumulation between the internal elastic lamina and media [12,150]; or (c) the dissection plane lies between the media and the adventitia, causing outpouching of arterial wall [12]. Intracranial arteries are prone to subadventitial dissection [164] and subsequently to SAH [8] due to lack of an external elastic lamina and thin muscular/adventitial layer [164].…”