The Source for Neurovascular News and Education

November 29, 2022


Strict monitoring of patients with near total occlusion, a TTP index > 1.22, or poor Circle of Willis compensation is warranted, researchers say.


Near total occlusion, a TTP index > 1.22, and poor Circle of Willis compensation are all risk factors for developing hyperperfusion-induced intracranial hemorrhage (ICH) following carotid artery stenting (CAS), according to a single-center retrospective study published online October 27, 2018, ahead of print in the Journal of NeuroInterventional Surgery.


Hyperperfusion-induced ICH carries an extremely high risk of morbidity and mortality in patients undergoing carotid intervention, whether that’s CAS or carotid endarterectomy (CEA), lead author Lei Zhang, MD, and senior investigator Jianmin Liu, MD (both of Changhai Hospital, Second Military Medical University, Shanghai, China), told TCTMD via email. “Such hemorrhage often has an insidious onset. Though it has a low incidence, the consequence can be detrimental,” they said.


“Previous studies mainly focused on analyzing risk factors for hyperperfusion syndrome (HPS),” they continued. “Few have reported on hyperperfusion-induced ICH directly. Certain questions with respect to whether HPS and hyperperfusion-induced ICH share the same risk factors, whether hyperperfusion-induced ICH risk factors are specific, or how [its] development can be avoided, are creating confusions in our clinicians.”


This retrospective analysis was conducted to better characterize risk factors for hyperperfusion-induced ICH. Data on 201 patients with symptomatic severe carotid stenosis (70-99%) who underwent carotid artery stenting between June 2009 and June 2015 at a single center in China were evaluated. The investigators looked at whether patients’ clinical baseline data, imaging features, and treatment strategies were associated with the risk of developing the complication.


Overall, seven patients (3.3%) developed hyperperfusion-induced ICH. The study authors attribute this relatively high incidence to the fact that only patients with severe stenosis were included in the study. All of these patients had near total occlusion, based on the NASCET criteria, and all developed the condition within 2 days of surgery.


The incidence of hyperperfusion-induced ICH among patients with near total occlusion was significantly higher than among those without. In addition, patients with poor compensation of Willis’ Circle were more likely to develop the complication. Five of the seven patients had no development of either anterior or posterior circulations, and two had no development of anterior circulation and poor development of posterior circulation.


All patients received preoperative CT perfusion, and TTP index was defined as the TTP ratio between the affected and contralateral side. TTP index was significantly different between patients with versus without hyperperfusion-induced ICH.


Factors Associated With Hyperperfusion-Induced ICH



(n = 7)


(n = 203)

P Value

Near Total Occlusion



< 0.001

Good Compensation of Anterior and Posterior Circulation



< 0.001

TTP Index

1.30 ± 0.15

1.15 ± 0.10

< 0.001


An analysis of the receiver operating characteristic curve indicated that patients with TTP index > 1.22 were more likely to develop hyperperfusion-induced ICH, with a sensitivity of 100% and specificity of 75.9%.


Close Monitoring Needed


“We should control perioperative blood pressure,” recommend the authors. “For patients with a high risk of hyperperfusion-induced ICH, staged treatment may be considered,” although they acknowledge a need to develop an appropriate plan for staged treatment as well as studies to evaluate its safety and efficacy in this clinical context.


They also recommend strict postsurgical monitoring of patients with a preoperative TTP index > 1.22, near complete occlusion, and poor compensation of both anterior and posterior circulations.




Zhang L, Dai D, Li Z, et al. Risk factors for hyperperfusion-induced intracranial hemorrhage after carotid artery stenting in patients with symptomatic severe carotid stenosis evaluation. J NeuroIntervent Surg. 2018;Epub ahead of print.



Zang reports no relevant conflicts of interest.