LAUSR

Dear Editor-in-Chief, We read with great interest the recent letter to the editor submitted by Koopman et al. [1] regarding an unusual case of hyperperfusion on CT perfusion imaging of acute ischemia in an adult patient. In contrast to adult patients, our experience suggests that this pattern is relatively more common in pediatric patients with large vessel stroke, including both perinatal and pediatric arterial ischemic stroke (AIS).When neuroimaging evaluation for new-onset neurologic findings reveals acute AIS, we frequently note that spontaneous recanalization of the presumed occluded vessel has either already occurred (Figs. 1 and 2), or occurs within the first several hours following presentation (Figs. 3 and 4), resulting in hyperperfusion on SWI or MR perfusion in the area of infarct. Limited investigation of perfusion patterns in perinatal [2–5] AIS support this observation, with 57% (12/21) of the pooled reported patients in perinatal AIS demonstrating a hyperperfusion pattern on SWI and MR perfusion in the area of infarction on DWI/ADC, 33% (7/21) demonstrating a mixed perfusion pattern, and only 10% (2/21) demonstrating a hypoperfusion pattern. Similarly, Chen et al. demonstrated that only 50% of pediatric AIS in a series of 10 patients investigated with MR perfusion demonstrated hypoperfusion in the infarct core, with the remaining 20% demonstrating hyperperfusion, 20% normal perfusion, and 10% a mixed pattern [6]. These data are in contrast to the rates of spontaneous recanalization with consequent luxury perfusion in adult patients with AIS, which are estimated to range from 14 to 28% at 6–8 h, increasing to approximately 50% nonocclusion by 4 days after stroke in the absence of intervention [7]. It remains unclear whether any greater propensity of pediatric patients with AIS to present with open vessels represents a greater tendency toward early spontaneous thrombolysis, delayed presentation for neuroimaging evaluation due to diagnostic uncertainty, or some combination of these factors. Whatever the reason, this tendency contributes to the currently limited ability of pediatric stroke patients to benefit from evolving intravenous and intraarterial thrombolytic therapies available to adult stoke patients.