Predictors of hyperperfusion syndrome before and immediately after carotid artery stenting in single-photon emission computed tomography and transcranial color-coded real-time sonography studies.

Background: Hyperperfusion syndrome (HPS) is a critical complication after carotid artery stenting (CAS) and carotid endarterectomy (CEA).

Objective: To identify predictors of HPS before and immediately after CAS.

Methods: We analyzed patients who underwent elective CAS from 2005 to 2008, and underwent single-photon emission computed tomography (SPECT) and transcranial color-coded real-time sonography before and immediately after CAS. HPS was defined as post-CAS deteriorating neurological conditions with headache not secondary to cerebral ischemia. We assessed the measures of blood flow between the two cortical hemispheres by taking the ratio of cerebral blood flow (CBF) of the affected to unaffected hemisphere excluding any ischemic/infarcted areas (asymmetry index); the measures of blood flow within each cortical hemisphere by comparing the CBF in the affected cortical hemispheric area to the CBF in the ipsilateral cerebellar hemisphere (middle cerebral artery [MCA]-to-cerebellar activity ratio); cerebral vasoreactivity (CVR); MCA mean blood flow velocity in the affected hemisphere; and MCA mean blood flow velocity ratio (preoperative to postoperative).

Results: Sixty-four patients were analyzed retrospectively. Nine patients presented with HPS. Logistic regression analysis showed that CVR (P<.01) and MCA mean blood flow velocity (P<.05) were the significant predictors among the pre-CAS variables, and that MCA mean blood flow velocity ratio (P<.05) and MCA-to-cerebellar activity ratio change (P<.05) were significant predictors among the post-CAS variables.

Conclusion: SPECT and transcranial color-coded real-time sonography studies are useful in predicting HPS.