Ischemic Stroke - Hennepin County Medical Center

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Case Reports Figure One. Head CT perfusion study. The right upper quadrant shows cerebral blood volume (CBV), the left lower quadrant shows cerebral blood flow (CBF), and the right lower quadrant demonstrates mean transit time (MTT). This study shows marked asymmetry in CBF and MTT between the right and left middle cerebral artery (MCA) distributions. The reduction in the right MCA territory quantitatively meets ischemia criteria. The CBV is essentially normal in the right MCA, which suggests that this is ischemia rather than infarction. was beyond 3 hours for the intravenous thrombolytic window, beyond 6 hours for the standard intra-arterial thrombolytic window and beyond 8 hours for the current standard mechanical thrombectomy window. The initial MRI showed a relatively small area of infarction despite significant clinical symptoms. The CT perfusion was important in determining the presence of salvageable brain tissue and his candidacy for treatment despite the late time window. CT perfusion involves two contrast boluses and several timed CT cuts through the lentiform nuclei and the supraventricular white matter. The images are reconstructed to represent quantitative color maps of cerebral blood volume, cerebral blood flow and mean transit time. Comparison between the right and left hemispheres in the cerebral artery distributions can differentiate between infarction and ischemia, and delineate tissue in watershed locations that may still be viable and survive if blood flow is restored. In this case, CT perfusion was able to differentiate between the small area of infarcted brain parenchyma and the large area of ischemic tissue that was still viable and would respond to restoration of blood flow. With the advent of CT perfusion scan to differentiate between infarction and ischemia, and cerebral angiography with numerous adjunct treatment modalities such as angioplasty, intra-arterial thrombolytics and mechnical thrombectomy devices, the standard time window of 0-6 hours may be extended to a longer time window in select patients. Case Three A case of delayed intra-arterial thrombolysis in cerebrovascular accident by Lisa M. Hayden, M.D. Department of Emergency Medicine Hennepin County Medical Center Abstract Though cerebrovascular accident (CVA) is considered a disease of elders, 25% of CVA occurs in patients less than 65 years of age. 8 | Approaches in Critical Care | December 2008
Case Reports Guidelines regarding early recognition and treatment of CVA are well established. Intraarterial thrombolysis (IAT) has been shown to improve outcomes in a select group of patients with thrombosis of the middle cerebral artery (MCA). Class I recommendations by the American Stroke Association include IAT for patients who are not candidates for intravenous thrombolysis and who present to a stroke center with thrombus in the MCA within 6 hours of symptom onset. This case involves a young patient who underwent delayed IAT with a successful outcome. Case report A 29 year-old male with no significant past medical history presented to a local emergency department with sudden onset of severe leftsided headache, profound right-sided weakness and slurred speech about 30 minutes after sexual intercourse. A head CT showed no evidence of infarction or hemorrhage. The patient’s symptoms completely resolved after symptomatic treatment of the headache (about 1-2 hours from onset) and he was discharged to home. The patient fell asleep around 4:00 a.m. feeling normal. He awoke at 10:00 a.m. with aphasia and right-sided weakness and returned to the hospital. A repeat head CT at this time showed small hypodensities in the region of his left MCA. He was transferred to a stroke center with persistent right-sided facial droop and profound weakness of the right upper and lower extremities. Upon arrival at the stroke center, his vital signs were temperature 35.9° Celsius, BP 153/77, HR 75, RR 17, and O2 saturation of 100%. An emergent CT perfusion showed a large perfusion deficit with a small area of infarction in the territory of the left MCA, consistent with a large area of at-risk but salvageable brain tissue. CT angiogram showed a small focal thrombus in the proximal segment of the MCA. Emergent MRI confirmed a small amount of existing stroke in the left MCA distribution. Cerebral angiogram by the neurointerventionalist revealed an occlusion of the left M1 with a string of delayed flow around the thrombus. Low-dose intra-arterial alteplase (2 mg) was administered directly into the clot approximately 17 hours after his initial presentation and just over 12 hours after he went to sleep feeling normal again after the first transient ischemic attack (TIA). Intra-arterial thrombolytic treatment was chosen over mechanical embolectomy despite the late time window because a small clot burden was seen that would likely respond to the thrombolytic treatment. The angiogram showed partial resolution of the clot and significant improvement in distal perfusion of his left MCA. (See Figure One on page 10.) Intravenous Integrilin ® was administered to prevent vessel reocclusion and facilitate further clot lysis. A follow-up angiogram showed a spontaneous dissection in the area of the thrombus, which was thought to be the cause of occlusion. At a later date, the patient underwent stenting of his left M1 dissection and is currently on aspirin and Plavix ® . Other workups, including labs for hypercoaguable disease and imaging for cardiac sources of thromboembolism, were negative. The remainder of the patient’s hospital course was unremarkable and at the one-year follow-up, the patient’s only remaining deficit was an occasional tremor of his right hand at rest. He is back to work and otherwise living a normal life. Discussion American Stroke Association class I recommendations for IAT include patients presenting within 6 hours of symptom onset with ischemic CVA to the MCA, who are not candidates for intravenous thrombolysis (IVT). Class I recommendations also include IAT by a qualified interventionalist at a center with access to cerebral angiogram. Preliminary data show significant benefit of IAT versus placebo. One example is the PROACT II trial, which has shown favorable results for IAT use. One aspect of this study compared patients who Approaches in Critical Care | December 2008 | 9
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