Silent ischemia after neuroprotected percutaneous carotid stenting: A diffusion-weighted MRI study

Abstract

BACKGROUND AND PURPOSE: To assess by diffusion-weighted MR imaging (DWI) the efficacy of cerebral protection devices in avoiding embolization and new ischemic lesions in patients with severe internal carotid artery (ICA) stenosis undergoing carotid artery stent placement (CAS). METHODS: One hundred sixty-two CASs in the extracranial ICA were performed with the use of distal filters. Mean age of the patients was 68.5 years (range, 33-86) and 122 patients (75.3%) were symptomatic. MR imaging was performed in all patients during the 3-day period before CAS, and DWI was obtained within 24 hours after the procedure. Ninety-five patients (58.6%) were monitored by transcranial Doppler ultrasonography for microemboli detection in the territory of the middle cerebral artery (MCA), ipsilateral to the vessel being treated. RESULTS: Twenty-eight patients (17.3%) showed 58 new ischemic foci in DWI, and 13 patients (46.4%) had multiple foci. Location of new lesions was mainly in the vascular territory supplied by the treated vessel (19 patients; 67.9%), but also in the contralateral MCA (1 patient; 3.6%), and the posterior fossa (4 patients; 14.3%). A significant relationship (P Ͻ .03) was found between occurrence of transient ischemic attack (TIA) and appearance of new lesions. Microembolic signals (MES) were detected in 88 patients (92.6%), with no relationship between number of MES and the appearance of new ischemic foci. CONCLUSION: New ischemic foci were observed in 17.3% of the patients undergoing neuroprotected CAS. Appearance of new ischemic lesions were only significantly related to the occurrence of TIA but not to the number of MES registered or other variables. Despite the encouraging results, the incidence of new ischemic lesions should promote research for safer techniques and devices.

Cerebral Ischemic Lesions Detected With Diffusion-Weighted Magnetic Resonance Imaging After Carotid Artery Stenting: Comparison of Several Anti-embolic Protection Devices

“…30) Cerebral embolic events may occur during diagnostic angiography performed at early CAS caused by thromboembolism or air embolism introduced by injection of contrast medium or catheter flushing. 23) The apparently high incidence of contralateral lesions matched previous studies using diagnostic angiography. New ischemic lesions occurred in 29% of 59 patients after diagnostic angiography, and the frequency of lesions was correlated to the amount of contrast medium, timing of the procedure, number of vessels difficult to probe, and use of more than one catheter.…”

“…Microembolic lesions detectable with diffusion-weighted imaging appeared in 26% of patients treated with a distal filter device versus 36% of patients treated with unprotected CAS. 8) A series of 162 CAS procedures involved distal ischemic events in 17.3% of patients, and the number of lesions per patient was 2.07, 23) compared to 2.8 in our study. However, all filtration devices have programmed pores to permit antegrade blood flow, which may allow particles smaller than the pore size to pass through the filter, and these Distal Ischemia After CAS small microemboli may not be visible using diffusion-weighted imaging.…”

Hemodynamic Instability Increases New Ischemic Brain Lesions on Diffusion-Weighted Imaging After Carotid Artery Stenting

“…However, there is no established relationship between the number of microembolic signals and the incidence of new ischemic brain lesions detected on DWI. 15) Almost all microembolisms produced during CAS are thought to be washed out, as previously proposed. 6) In patients with carotid artery stenosis of more than 50%, a decrease in blood pressure would not produce an active vascular response, but would reduce cerebral blood volume and velocity due to impairment of dynamic cerebral autoregulation.…”

Oxidative injury associated with stenting of asymptomatic carotid artery stenosis

“…1.16 % and 0.74 %, respectively, while after carotid stenting CHS and ICH occurred in 1.9 % and 0.37 % of patients correspondingly [4] The study by Saraçoğlu E. et al showed a positive correlation between CHS and oxidative stress biomarkers emphasizing that measurement of oxidative stress perioperatively might play a role in the diagnosis and treatment of the hyperperfusion syndrome.…”

“…Symptoms such as ipsilateral migraine-like headaches, seizures, and transient focal neurologic defi cits in the absence of cerebral ischaemia in MRI images are attributed to cerebral hyperperfusion syndrome. According to respective literature, incidences of the CHS syndrome after carotid revascularization vary from 0.2 % to 18.9 % [4]. The presence of symptoms is essential to the defi nition of the syndrome.…”