Early carotid endarterectomy after ischemic stroke improves diffusion/perfusion mismatch on magnetic resonance imaging: Report of two cases

OBJECTIVE AND IMPORTANCE: The functional magnetic resonance imaging techniques of diffusion-weighted imaging and perfusion-weighted imaging allow for ultra-early detection of brain infarction and concomitant identification of blood flow abnormalities in surrounding regions, which may represent brain "at risk." CLINICAL PRESENTATION: We report two patients with acute ischemic stroke associated with ipsilateral high-grade carotid stenosis. The first patient, a 64-year-old woman with a remote history of ischemic stroke and a vertebral artery aneurysm, presented with worsening of her preexisting right hemiparesis. The second patient, another 64-year-old woman with known multiple intracranial aneurysms and bilateral high-grade internal carotid artery stenosis, was admitted for the elective microsurgical clipping of an enlarging giant left carotid-ophthalmic artery aneurysm. Postoperatively, she developed right hemiparesis and mild aphasia. Both patients showed progressive worsening of their neurological deficits in the setting of small or undetected diffusion-weighted imaging abnormalities and large perfusion-weighted imaging defects. INTERVENTION: After prompt carotid endarterectomy, symptoms in both patients resolved or improved. Follow-up magnetic resonance imaging scans demonstrated resolution or significant improvement in the perfusion abnormalities in both patients. CONCLUSION: Carotid endarterectomy in the setting of diffusion-weighted/perfusion- weighted imaging mismatch can lead to improvement in cerebral perfusion as evidenced by resolution of the perfusion-weighted imaging lesion. Diffusion/perfusion magnetic resonance imaging may be useful in identifying patients with severe neuro-logical deficits but without large territories of infarction who may safely undergo early surgical revascularization.