Utility of CT perfusion scanning in patient selection for acute stroke intervention: experience at University at Buffalo Neurosurgery-Millard Fillmore Gates Circle Hospital

Evolution of endovascular mechanical thrombectomy for acute ischemic stroke

Acute ischemic stroke (AIS) is a common medical problem associated with significant morbidity and mortality worldwide. A small proportion of AIS patients meet eligibility criteria for intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator, and its efficacy for large vessel occlusion is poor. Therefore, an increasing number of patients with AIS are being treated with endovascular mechanical thrombectomy when IVT is ineffective or contraindicated. Rapid advancement in catheter-based and endovascular device technology has led to significant improvements in rates of cerebral reperfusion with these devices. Stentrievers and modern aspiration catheters have now surpassed earlier generation devices in the degree and rapidity of revascularization. This progress has been achieved with no concurrent increase in risk of major complications or mortality, both when used alone or in combination with IVT. The initial randomized controlled trials comparing endovascular therapy to IVT for AIS failed to show superior outcomes with endovascular treatment, but key limitations of each trial may limit the significance of these results to current practice. While endovascular devices and operator experience continue to evolve, we are optimistic that this will be accompanied by improvements in patient outcomes. This review highlights the major endovascular devices used in current practice and the trials which have investigated their efficacy.

Saving the ischemic penumbra: endovascular thrombolysis versus medical treatment

Endovascular thrombolysis may allow rapid arterial recanalization in patients with acute ischemic stroke. We present the first study to our knowledge comparing the ischemic penumbra saved with endovascular versus medical therapy. A retrospective review of 21 patients undergoing endovascular intervention for stroke from 2010 to 2011 was contrasted with 21 consecutive patients treated with antiplatelet agents alone. Immediate computed tomography perfusion (CTP) scan of the head and neck was obtained in all patients. Patients with lacunar and posterior circulation infarcts, and those who were medically unstable for MRI post-operatively were excluded. CTP and MRI underwent volumetric calculation. CTP penumbra was correlated with diffusion restriction volumes on MRI, and an assessment was made on the volume of ischemic burden saved with either endovascular treatment or antiplatelet agents. The median age was 70 years (interquartile range 62-80). Median National Institutes of Health Stroke Scale score was 18 and 14 in the control and endovascular groups, respectively. Intravenous tissue plasminogen activator was administered in 22 of 42 patients (52%). Median penumbra calculated was 32,808 mm(3) in the control group and 46,255 mm(3) in the endovascular group. Median penumbra spared was 9550 mm(3) (4980-18,811) in the control group versus 38,155 mm(3) in the endovascular group (p=0.0001). Endovascular thrombolysis may be more efficient than medical therapy alone in saving ischemic penumbra. Future advances in recanalization techniques will further improve the efficacy of endovascular therapy.

CT perfusion-guided versus time-guided mechanical recanalization in acute ischemic stroke patients

OBJECTIVE

Perfusion studies are increasingly used to triage acute stroke patients for endovascular recanalization therapies. We compare the safety and efficacy of CT perfusion (CTP)-guided to time-guided mechanical recanalization in acute ischemic stroke (AIS) patients.

METHODS

A review was conducted on 132 patients, 94 undergoing CTP-guided and 38 undergoing time-guided (maximum 8h from symptom onset) mechanical recanalization at our institution.

RESULTS

The rate of partial-to-complete recanalization did not differ between the CTP and the non-CTP group (78.7% vs. 81.6%, respectively, p=0.71). ICH occurred respectively in 18.1% in the CTP group versus 31.6% in the non-CTP group (p=0.06). The overall in-hospital mortality rate was significantly lower in the CTP group (15.9% vs. 36.8%, p=0.04). In multivariable analysis, CTP-guided patient selection was an independent negative predictor of in-hospital mortality (OR=3.2; p=0.01). CTP-guided patient selection, however, was not a predictor of favorable outcome (Modified Rankin Scale 0-2 or 0-3).

CONCLUSIONS

CTP-based patient selection was associated with lower ICH and mortality rates. Favorable outcomes, however, did not differ between the 2 groups. These results may suggest a possible benefit in terms of in-hospital mortality with CTP-guided triage of AIS patients for endovascular treatment.

Computed Tomography Workup of Patients Suspected of Acute Ischemic Stroke

Background and Purpose—

To determine whether perfusion computed tomography (PCT) adds value to noncontrast head CT (NCT), CT angiogram (CTA), and clinical assessment in patients suspected of acute ischemic stroke.

Methods—

We retrospectively reviewed 165 patients with acute ischemic stroke. PCT was used to calculate the volumes of infarct core and ischemic penumbra on admission. Other imaging data included Alberta Score Program Early CT Score, site of occlusion, and collateral flow. Clinical data included age, time, National Institutes of Health Stroke Scale at baseline, treatment type, and modified Rankin score (mRS) at 90 days. Recanalization status was assessed on follow-up imaging. In a first multivariate regression analysis, we assessed whether volumes of PCT penumbra and infarct core could be predicted from clinical variables, NCT, or CTA, or whether they represented independent information. In a second multivariate regression analysis, we used mRS at 90 days as outcome and determined which variables predicted it best.

Results—

Of 165 patients identified, 76 had a mRS score of 0 to 2 at 90 days, 89 had a mRS score >2. PCT infarct could be predicted by clinical data, NCT, CTA, and combinations of this data ( P <0.05). PCT penumbra could not be predicted by clinical data, NCT, and CTA. All of the variables but NCT and CTA were significantly associated with 90-day mRS outcome. The single most important predictor was recanalization status ( P <0.001). PCT penumbra volume ( P =0.001) was also a predictor of clinical outcome, especially when considered in conjunction with recanalization through an interaction term ( P <0.001).

Conclusions—

PCT penumbra represents independent information, which cannot be predicted by clinical, NCT, and CTA data. PCT penumbra is an important determinant of clinical outcome and adds relevant clinical information compared with a stroke CT workup, including NCT and CTA.

Multimodal endovascular management of acute ischemic stroke in patients over 75 years old is safe and effective

Introduction

Greater attention has been directed to endovascular recanalization of acute ischemic stroke in septuagenarians and above.

Technique

A retrospective chart review was conducted to include patients treated for acute ischemic stroke from 2006 to 2012. All patients underwent initial neurological assessment and non-contrast head CT. Patients treated from 2009 to 2012 additionally received emergent CT angiogram and CT perfusion. 51 patients met the clinical and radiographic criteria and underwent multimodal endovascular revascularization for acute ischemic events.

Results

All patients underwent cerebral angiography and met angiographic criteria for endovascular thrombolysis. 34 patients (67%) were older than 80 years of age. 23 patients (45%) received intravenous tissue plasminogen activator prior to admission. Eight (16%) patients underwent stent placement after intra-arterial thrombolysis, 10 (20%) underwent balloon angioplasty and seven (14%) underwent both angioplasty and stent placement. 21 (41%) required only intra-arterial thrombolytics. An improvement in Thrombolysis in Myocardial Infarction score was noted in 34 patients (67%). The average modified Rankin Scale score on discharge was 3.9. Symptomatic intracranial hemorrhage occurred in three patients (6%); none required surgery. One patient (1.9%) had a postoperative retroperitoneal hematoma, which was managed conservatively. Two fatalities resulted from intraoperative vessel rupture (3.9%), with a combined morbidity and mortality of 27.5%.

Conclusions

Multimodal endovascular recanalization of acute ischemic stroke is a relatively safe treatment option in patients older than 75 years of age. Careful patient selection by clinical and radiographic inclusion criteria is necessary for the successful management of stroke in this age group.

Standardization of Stroke Perfusion CT for Reperfusion Therapy

With the advances in terms of perfusion imaging, the "time is brain" approach used for acute reperfusion therapy in ischemic stroke patients is slowly being replaced by a "penumbra is brain" or "imaging is brain" approach. But the concept of penumbra-guided reperfusion therapy has not been validated. The lack of standardization in penumbral imaging is one of the main contributing factors for this absence of validation. This article reviews the issues underlying the lack of standardization of perfusion-CT for penumbra imaging, and offers avenues to remedy this situation.