Microembolism Versus Hemodynamic Impairment in Rosary-Like Deep Watershed Infarcts: A Combined Positron Emission Tomography and Transcranial Doppler Study

• Published in: Stroke (1970) 2011-11, Vol.42 (11), p.3138-3143
• Main Authors: REDA MOUSTAFA, Ramez, MOMJIAN-MAYOR, Isabelle, SIMON JONES, P, MORBELLI, Silvia, DAY, Diana J, AIGBIRHIO, Franklin I, FRYER, Tim D, WARBURTON, Elizabeth A, BARON, Jean-Claude
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Biological and medical sciences; Cerebral Infarction - diagnosis; Cerebral Infarction - physiopathology; Female; Hemodynamics - physiology; Humans; Intracranial Embolism - diagnosis; Intracranial Embolism - physiopathology; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Nervous system; Neurology; Positron-Emission Tomography - methods; Prospective Studies; Ultrasonic investigative techniques; Ultrasonography, Doppler, Transcranial - methods; Vascular diseases and vascular malformations of the nervous system
• ISSN: 0039-2499; 1524-4628
• DOI: 10.1161/STROKEAHA.111.616334

Deep watershed infarcts are frequent in high-grade carotid disease and are thought to result from hemodynamic impairment, particularly when adopting a rosary-like pattern. However, a role for microembolism has also been suggested, though never directly tested. Here, we studied the relationships among microembolic signals (MES) on transcranial Doppler, rosary-like deep watershed infarcts on brain imaging, and cerebral hemodynamic compromise on positron emission tomography (PET), all in severe symptomatic carotid disease. We hypothesized that rosary-like infarcts would be significantly associated with worse hemodynamic status, independent of the presence of MES. Sixteen patients with ≥70% carotid disease ipsilateral to recent transient ischemic attack/minor stroke underwent magnetic resonance imaging including diffusion-weighted imaging, (15)O-PET, and transcranial Doppler. Mean transit time, a specific marker for hemodynamic impairment, was obtained in the symptomatic and unaffected hemispheres. Eleven of 16 patients had rosary-like infarcts (Rosary+) and 8 patients had MES. Mean transit time was significantly higher (P=0.008) in Rosary+ patients than in healthy controls (n=10), and prevalence of MES was not different between Rosary+ and Rosary- patients. Contrary to our hypothesis, however, the presence of MES within the Rosary+ subset was associated (P=0.03) with a better hemodynamic status than in their absence, with a significant (P=0.02) negative correlation between mean transit time and rate of MES/h. Contrary to mainstream understanding, rosary-like infarcts were not independent of presence and rate of MES, suggesting that microembolism plays a role in their pathogenesis, probably in association with hemodynamic impairment. Pending confirmation in a larger sample, these findings have management implications for patients with carotid disease and rosary-like infarcts.