Reversed Robin Hood syndrome in a patient with luxury perfusion after acute ischemic stroke.

A 49-year-old man presented with a 1-day history of multiple transient episodes of right-sided weakness. The episodes were stereotypical, precipitated by exertion, and lasted 5 to 10 minutes. He denied any chest pain, palpitation, headache, or injury. He was a chronic smoker (40 cigarettes per day for 20 years) and denied any past or family history of hypertension, diabetes mellitus, dyslipidemia, stroke, or ischemic heart disease. On arrival, he was fully conscious and oriented and had regular pulse (65 bpm), and blood pressure (145/90 mm Hg). Some word-finding difficulties and mild right-sided weakness (power, Medical Research Council grade 4) were noted (National Institute of Health Stroke Scale score, 4 points). Magnetic resonance imaging of the brain (Figure 1A) revealed multiple areas of restricted diffusion in the left middle cerebral artery (MCA) territory. Although the classic ultrasonographic findings were not seen on carotid duplex, the absence of significant atherosclerotic plaques and smooth tapering with severe luminal narrowing of internal carotid artery (ICA) strongly suggested a possible arterial dissection. The findings were confirmed on digital subtraction angiography (Figure 1B). Transcranial Doppler ultrasonography revealed anterior cross-filling of the left MCA via a patent anterior communicating artery. No spontaneous microembolic signals were noted on extended monitoring. Vasomotor reactivity1 was evaluated during voluntary breath holding for 30 seconds with simultaneous recording of both MCAs. Normal flow acceleration was noted in the right MCA during breath holding, but at the same time, the left MCA demonstrated a paradoxical reduction in flow velocities resulting from the intracranial steal phenomenon (Figure 2), the socalled reversed Robin Hood syndrome.2 Metabolic perfusion and cerebral vasodilatory reserve were evaluated by acetazolamide-challenged technetium-99–hexamethylpropyleneamine oxime single-photon emission computed tomography.3 Significantly increased perfusion (Figure 1G) in the left MCA territory despite multiple ischemic infarctions and severe ICA steno-occlusive disease suggested “luxury perfusion.” However, a paradoxical reduction in the metabolic perfusion in the left MCA territory (Figure 1H) occurred after the vasodilatory challenge with acetazolamide, consistent with reversed Robin Hood syndrome on transcranial Doppler ultrasonography. Power in the patient’s right extremities deteriorated transiently (to Medical Research Council grade 3, lasting 10 minutes) during the acetazolamide challenge. Figure 1. Neuroimaging findings in a patient with severe stenoocclusive disease of left ICA. Diffusion-weighted magnetic resonance imaging (A) shows multiple areas of restricted diffusion in the left MCA. Severe luminal narrowing of the left ICA with smooth tapering seen on digital subtraction angiography (B) suggests an arterial dissection. Increased cerebral blood volume (CBV) and cerebral blood flow (CBF) are noted in the left MCA territory despite an elevated mean transit time (MTT) on computed tomographic perfusion imaging (C through F). Baseline technetium-99– hexamethylpropyleneamine oxime single-photon emission computed tomography imaging (G) shows significantly increased perfusion in the left MCA territory despite multiple ischemic infarcts and severe ICA disease (luxury perfusion). Single-photon emission computed tomography imaging after acetazolamide (Diamox) challenge (H) shows a paradoxical reduction in the left MCA territory perfusion resulting from the reversed Robin Hood syndrome.