RESUMEN
Transarterial embolization using Onyx is a well-established treatment for dural arteriovenous fistulas (DAVFs). However, complications can arise when Onyx migrates into the venous side, impairing the draining veins. We encountered a case where Onyx, injected through the arterial side, strayed into the jugular vein, forming a hairball-like structure. Our study aimed to investigate the underlying mechanism of this unusual phenomenon. We postulated that Onyx precipitates into thread-like shapes when passing through extremely narrow openings. To test this, we extruded Onyx from a syringe through a 27-gauge needle into a silicone tube with flowing water. By varying the flow speed, we observed the hardening behavior of Onyx. Under slow flow, the extruded Onyx quickly solidified at the needle tip, forming a round mass. Conversely, high-speed flow resulted in Onyx being dispersed as small pieces. We successfully replicated the formation of “Onyx threads” under continuous slow flow conditions, similar to our case. This phenomenon occurs when Onyx unexpectedly migrates to the draining vein through a tiny opening during transarterial embolization for arteriovenous shunt diseases. Early recognition and appropriate measures are necessary to prevent occlusive complications in the draining veins and the pulmonary system.
RESUMEN
Purpose@#We investigated the age distribution of cerebral saccular aneurysms in various locations to clarify the differences by location and discuss the mechanism of formation. @*Materials and Methods@#We retrospectively assessed clinical material obtained from 1,252 unruptured aneurysms treated with endovascular embolization between 2004 and 2019. Age, sex, laterality, and size were investigated by the location of aneurysms, classified as cavernous internal carotid artery (ICA), paraclinoid ICA, supraclinoid ICA, anterior communicating artery, anterior cerebral artery, middle cerebral artery, basilar artery complex, and posterior inferior cerebellar artery. Paraclinoid aneurysms were subclassified into 3 patterns according to their projecting direction: S-type, with superior protrusion; M-type, with medial protrusion; and P-type, with posteroinferior protrusion. @*Results@#There was no significant difference by location for sex, laterality, and size. The mean age of patients with paraclinoid aneurysms (56.5 years old) was significantly lower than that of other aneurysm patients (64.3 years old). Notably, 40% of the patients with M-type aneurysms were <50 years old. This percentage was significantly higher than that of aneurysms at other locations (P<0.05). @*Conclusion@#We found a young female predominance for patients with paraclinoid carotid aneurysms. This study may suggest that congenital factors contribute to paraclinoid aneurysm formation as well acquired factors, such as hemodynamic stress, atherosclerotic wall damage, and local inflammation.
RESUMEN
Purpose@#We investigated the age distribution of cerebral saccular aneurysms in various locations to clarify the differences by location and discuss the mechanism of formation. @*Materials and Methods@#We retrospectively assessed clinical material obtained from 1,252 unruptured aneurysms treated with endovascular embolization between 2004 and 2019. Age, sex, laterality, and size were investigated by the location of aneurysms, classified as cavernous internal carotid artery (ICA), paraclinoid ICA, supraclinoid ICA, anterior communicating artery, anterior cerebral artery, middle cerebral artery, basilar artery complex, and posterior inferior cerebellar artery. Paraclinoid aneurysms were subclassified into 3 patterns according to their projecting direction: S-type, with superior protrusion; M-type, with medial protrusion; and P-type, with posteroinferior protrusion. @*Results@#There was no significant difference by location for sex, laterality, and size. The mean age of patients with paraclinoid aneurysms (56.5 years old) was significantly lower than that of other aneurysm patients (64.3 years old). Notably, 40% of the patients with M-type aneurysms were <50 years old. This percentage was significantly higher than that of aneurysms at other locations (P<0.05). @*Conclusion@#We found a young female predominance for patients with paraclinoid carotid aneurysms. This study may suggest that congenital factors contribute to paraclinoid aneurysm formation as well acquired factors, such as hemodynamic stress, atherosclerotic wall damage, and local inflammation.