Intracranial artery to artery spontaneous revascularization in a child

Development of Collateral Vessels after Anterior Circulation Large Vessel Occlusion in Pediatric Arterial Ischemic Stroke Relates to Stroke Etiology: A Longitudinal Study

BACKGROUND AND PURPOSE

The characteristics of large vessel occlusion (LVO) in the acute phase of pediatric arterial ischemic stroke and their natural history according to stroke etiology are poorly explored. This studied aimed at describing the prevalence and the radiological evolution of LVO in pediatric AIS.

MATERIALS AND METHODS

This single-center retrospective study included consecutive non-neonate children with acute arterial ischemic stroke, intracranial proximal LVO in the anterior circulation (MCA, anterior cerebral artery, and/or ICA), and clinical and imaging follow-up for at least 18 months, during a 9-year period.

RESULTS

Intracranial LVO was observed in 24.8% of patients with anterior circulation arterial ischemic stroke and adequate follow-up (n = 26/105), with a median age of 4.2 years (IQR 0.8-9), sex ratio 1.16. The main stroke etiology associated with LVO was unilateral focal cerebral arteriopathy (n = 12, 46%). During follow-up, a specific pattern of unilateral poststroke anastomotic bridge was observed in 8/26 patients, with the poststroke development of nonperforating collaterals forming a bridge in bypass of the LVO site with visible distal flow, within a median delay of 11 months. The development of unilateral poststroke anastomotic bridge was only observed in patients with unilateral focal cerebral arteriopathy. No patient with this pattern experienced stroke recurrence or further progressive vascular modifications.

CONCLUSIONS

After stroke, the development of unilateral poststroke anastomotic bridge is specifically observed in children with focal cerebral arteriopathy, appearing in the first year after stroke. This clinical-radiologic pattern was not associated with stroke recurrence or arterial worsening, differentiating it from progressive intracranial arteriopathy, such as Moyamoya angiopathy.

Revised concept of rete-like collateral formation: Rete mirabile does not exist in humans

The carotid rete is a physiological network between the external and internal carotid arteries (ICA) in lower vertebrates. However, true carotid rete does not exist in humans. This review aimed to contrast the physiological function of human "rete-like collaterals" with that of lower vertebrate "rete mirabile". An explanation for the development of rete-like collaterals in human intracranial arteries was also discussed. The rete mirabile (carotid, vertebral, spinal, and thoracic) in lower vertebrates has a specific physiological role and does not form vasculature for the same purpose in humans. Therefore, the term "rete mirabile" should not be used for cases reported in humans. Instead, "rete-like collaterals" is preferred. In the literature, rete-like or arterial anastomosis was observed in the ICA cavernous portion and the intradural arteries. Based on the hypothesis of the segmental concept, it applies to the ICA and intracranial arteries. Whether in the ICA, middle cerebral artery, posterior cerebral artery, or posterior inferior cerebellar artery, the segmental concept is the same and should be considered to have formed secondary collaterals after segmental regress or dysgenesis of affected arteries. Summarily, the significance of this review lies in its reevaluation of vascular structures previously described as "carotid rete" in humans to a true and preferred term, "rete-like collaterals". It also provides insights into the historical context and potential genetic factors associated with the formation of arteries in humans, contributing to a better understanding of human vascular anatomy.

Effect of vasa vasorum in cerebrovascular compensation: 2 case reports

Intracranial vasa vasorum (VV) are rare and develop predominantly in the proximal segments of the internal carotid artery (ICA) and vertebral artery (VA). The typical appearance of intracranial VV has not yet been reported in clinical practice. Although VV in the ICA have been found to re-institute the collateral flow, bypassing the obstructive segment, far less attention has been paid to the manner in which VV can connect the two ends of the obstructive segment through the plaque. In this study, we present two cases and discuss the positive effects of VV. In our first case, a patient with basilar artery (BA) occlusion and multiple infarcts in the posterior circulation territory received endovascular treatment. Digital subtraction angiography (DSA) showed the existence of VV, which originated from the proximal BA lumen, penetrated through the vessel wall, bypassed the obstructive segment, re-penetrated through the vessel wall, and reconnected to the distal BA lumen. Balloon angioplasty was performed, specifically avoiding the path of the VV, then the VV had disappeared in follow-up angiography. In our second case, a patient who had been diagnosed with occlusion in the initial segment of the left ICA two years ago suffered a stroke. DSA revealed that the VV collaterals penetrated directly through the plaque of obstructive site and reconnected to the distal vessel lumen, which caused low hemodynamic compensation. Angioplasty was performed directly following the VV path, then follow-up angiography showed the VV had disappeared. Arterial occlusion, including in the intracranial and extracranial artery, could trigger the occurrence of VV, which can improve downstream perfusion. VV also could play a role of signal light in endovascular treatment.