Acute ischemic stroke remains the most important neurologic malady in the world. Severe strokes caused by artery occlusion are a minority of all strokes, but cause most of the poor outcomes and costs associated with stroke. Neurointerventionalists have effective therapies, but too few stroke patients undergo endovascular procedures. The reasons are multiple, but a major reason is that patients too frequently arrive beyond the traditional time windows for treatment. A way to break out of this dilemma is described in the paper recently ePublished in the AJNR (N. Janjua, A. El-Gengaihy, J. Pile-Spellman, and A.I. Qureshi AJNR Am J Neuroradiol first published on February 4, 2009 as doi: 10.3174/ajnr.A1474).
The paper describes a small series of patients who were outside of the traditional stroke therapy window, but underwent endovascular therapy anyway. The majority of the patients had small DWI abnormalities in the setting of significant neurological symptoms (NIHSS greater than 8), a circumstance that has been termed a clinical-diffusion mismatch. Of those who underwent successful revascularization, all had significant clinical improvement, and none had intracerebral hemorrhage. The data makes physiological sense. Patients with major artery occlusions, severe neurological symptoms and small diffusion abormalities must have excellent collateral circulation that is sustaining neuronal viability despite synaptic dysfunction that produces the neurological syndrome.
If the findings described by Janjua et al. are confirmed, it begs the question of how many potential patients may fit the clinical-diffusion mismatch criteria. The number may be quite large as data from another paper by Copen et al. that was also recently ePublished (Existence of the Diffusion-Perfusion Mismatch within 24 Hours after Onset of Acute Stroke: Dependence on Proximal Arterial Occlusion Radiology. 2009 Jan 21. [Epub ahead of print]). Copen et al. found that well over half of all patients with a proximal anterior circulation occlusion had relatively small diffusion abnormalities.
Janjua and his co-authors have made an exceptional contribution to stroke research and I believe are lighting the path towards improved care of patients with the most severe strokes.
