Leptomeningeal Enhancement After Carotid Stenting
To the Editor:
We were very glad to see the recent study by Wilkinson et al1 to show the leptomeningeal enhancement by head MRI. We agreed with authors that the enhancement was mainly over the leptomeninges and that the leakage of contrast medium resulted in this leptomeningeal enhancement. However, we did not think such leakage was due to injury of the blood-brain barrier. It would be more accurate to say that the contrast medium leaked out of the vessels associated with the subarachnoid space/pia mater. A physiologist unselectively termed “blood-brain barrier” as the interface between blood and brain; in a strict sense, the blood-brain barrier should exist within the brain. Actually, it is the absence of blood-brain barrier in those vessels within the subarachnoid space.2 We would like to present our similar experience in brain CT here to demonstrate injury of the blood-brain barrier after stenting. Our patient was an 82-year-old woman who had left hemiplegia during the stenting of the right internal carotid artery. Therefore, she underwent a brain CT examination (with no further injection of contrast medium), approximately 7 hours after the beginning of the stenting procedure. Brain CT showed obvious enhancement at the hemisphere ipsilateral to stenting. The enhancement was mainly noted at the pia mater within the sulci as well as at the basal ganglion and surface of superficial cortex (Figure 1⇓). Interestingly, there was no more enhancement in these areas in the next day (Figure 2⇓). We observed such a phenomenon but could neither fully understand its significance nor draw a conclusion at that time, because the patient number was so small and because there were some questions to be clarified. We thought this increasing attenuation resulted mainly from the presence of contrast medium, and less likely from the leakage of red blood cell. Now, the MRI study of Wilkinson et al has also provided evidence to support our ideas. The enhancement over the sulci was interpreted as leakage of contrast medium through the vessels in the subarachnoid space. However, the enhancement within the brain should be considered a manifestation of injured blood-brain barrier.3 Nevertheless, we still had some questions at that time: (1) Was the impairment of vascular integrity due to chronic ischemia or secondary to stenting? (2) Was it possible to see such enhancement in patients who had no stroke after stenting? (3) How long would this phenomenon last? This MRI study has given us the answers to the first 2 questions but left the third question with no answer. According to their conclusion from the findings of MRI, the authors thought the leptomeningeal enhancement was a consequence of sudden hemodynamic change secondary to carotid stenting.1 However, on the basis of the study of Sage et al,4 it seems possible that the enhancement could result from increased permeability of vessels injured by injection of contrast medium.
- Copyright © 2000 by American Heart Association
Wilkinson ID, Griffiths PD, Hoggard N, Cleveland TJ, Gaines PA, Venables GS. Unilateral leptomeningeal enhancement after carotid stent insertion detected by magnetic resonance imaging. Stroke.. 2000;31:848–851.
Broadwell RD, Banks WA. Cell biological perspective for the transcytosis of peptides and proteins through the mammalian blood-brain fluid barrier. In: Pardridge WM, ed. The Blood-Brain Barrier: Cellular and Molecular Biology. New York, NY: Raven Press Ltd; 1993:165–200.
Orrison WW, Jr. Computed tomography and magnetic resonance imaging. In: Orrison WW Jr, ed. Introduction to Neuroimaging. Boston, Mass: Little, Brown & Co; 1989:65–174.
Sage MR, Drayer BP, Dubois PJ, Heinz ER, Osborne DR. Increased permeability of the blood-brain barrier after carotid Renografin-76. AJNR Am J Neuroradiol. 1981;2:272–274.