Prognostic significance of blood pressure variability after thrombolysis in acute stroke
MarekSykora, Dept. of Neurology, University Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germanymareksykora@yahoo.com
Jennifer Diedler, and Thorsten Steiner
Submitted August 15, 2008
We read the article by Delgado et al. with great interest. [1] The authors present an independent association between blood pressure (BP) variability and DWI lesion growth in ischemic stroke due to MCA occlusion.
The authors hypothesize that systemic BP fluctuations may negatively influence the ischemic penumbra in non-recanalized MCA occlusions. This association was not observed in patients who recanalized after rtPA. We would like to consider several issues.
In most complete MCA occlusions, insular involvement is present due to the direct supply from the main MCA trunk. Unfortunately, the authors have not recorded the insular injury. Lesions within the insular cortex are crucial in the pathogenesis of autonomic dysfunction in acute stroke including baroreflex impairment and sympathetic overdrive activation. This may result in increased BP variability. [2]
Furthermore, strokes affecting the insular cortex may be more prone to growth apart from initial lesion volume. [3] In the resulting autonomic imbalance, risks include pro-inflammatory cytokine production, elevated body temperature, hyperglycemia and increased blood-brain barrier permeability. [4] It is possible that BP variability is associated with insular lesions and reflects an underlying complex autonomic impairment which may contribute to infarct size growth. Recent data showed that beta blocker use was associated with less severe stroke implying that modulation of stroke-related autonomic dysfunction with beta blockers may reduce stroke size. [5]
We agree that increased BP variability in MCA occlusions with insular involvement may influence the stroke growth. However, other mechanisms should be considered. In addition, the issue of what should be considered causal and what can be considered an association remains unclear.
References
1. Delgado-Mederos R, Ribo M, Rovira A, et al. Prognostic significance of blood pressure variability after thrombolysis in acute stroke. Neurology. 2008 01.wnl.0000318294.36223.69v1 (e-Pub Ahead of print)
2. Sykora M, Diedler J, Rupp A, Turcani P, Steiner T. Impaired baroreceptor reflex sensitivity in acute stroke is associated with insular involvement, but not with carotid atherosclerosis. Stroke(in press).
3. Ay H, Arsava EM, Koroshetz WJ, Sorensen AG. Middle cerebral artery infarcts encompassing the insula are more prone to growth. Stroke 2008;39:373-378.
4. Emsley HC, Smith CJ, Tyrrell PJ, Hopkins SJ. Inflammation in acute ischemic stroke and its relevance to stroke critical care. Neurocrit Care. December 18 2007 (e-Pub Ahead of Print).
5. Laowattana S, Oppenheimer SM. Protective effects of beta-blockers in cerebrovascular disease. Neurology 2007;68:509-514.
We read the article by Delgado et al. with great interest. [1] The authors present an independent association between blood pressure (BP) variability and DWI lesion growth in ischemic stroke due to MCA occlusion.
The authors hypothesize that systemic BP fluctuations may negatively influence the ischemic penumbra in non-recanalized MCA occlusions. This association was not observed in patients who recanalized after rtPA. We would like to consider several issues.
In most complete MCA occlusions, insular involvement is present due to the direct supply from the main MCA trunk. Unfortunately, the authors have not recorded the insular injury. Lesions within the insular cortex are crucial in the pathogenesis of autonomic dysfunction in acute stroke including baroreflex impairment and sympathetic overdrive activation. This may result in increased BP variability. [2]
Furthermore, strokes affecting the insular cortex may be more prone to growth apart from initial lesion volume. [3] In the resulting autonomic imbalance, risks include pro-inflammatory cytokine production, elevated body temperature, hyperglycemia and increased blood-brain barrier permeability. [4] It is possible that BP variability is associated with insular lesions and reflects an underlying complex autonomic impairment which may contribute to infarct size growth. Recent data showed that beta blocker use was associated with less severe stroke implying that modulation of stroke-related autonomic dysfunction with beta blockers may reduce stroke size. [5]
We agree that increased BP variability in MCA occlusions with insular involvement may influence the stroke growth. However, other mechanisms should be considered. In addition, the issue of what should be considered causal and what can be considered an association remains unclear.
References
1. Delgado-Mederos R, Ribo M, Rovira A, et al. Prognostic significance of blood pressure variability after thrombolysis in acute stroke. Neurology. 2008 01.wnl.0000318294.36223.69v1 (e-Pub Ahead of print)
2. Sykora M, Diedler J, Rupp A, Turcani P, Steiner T. Impaired baroreceptor reflex sensitivity in acute stroke is associated with insular involvement, but not with carotid atherosclerosis. Stroke(in press).
3. Ay H, Arsava EM, Koroshetz WJ, Sorensen AG. Middle cerebral artery infarcts encompassing the insula are more prone to growth. Stroke 2008;39:373-378.
4. Emsley HC, Smith CJ, Tyrrell PJ, Hopkins SJ. Inflammation in acute ischemic stroke and its relevance to stroke critical care. Neurocrit Care. December 18 2007 (e-Pub Ahead of Print).
5. Laowattana S, Oppenheimer SM. Protective effects of beta-blockers in cerebrovascular disease. Neurology 2007;68:509-514.
Disclosures: The authors report no disclosures