Sebina Bulic, MD

Kamalian S, Kemmling A, Borgie RC, Morais LT, Payabvash S, Franceschi AM, et al. Admission Insular Infarction >25% Is the Strongest Predictor of Large Mismatch Loss in Proximal Middle Cerebral Artery Stroke. Stroke. 2013

Time is a brain. We have heard it so many times that we are conditioned to think and act in such manner, mainly, because it is true. That is why we keep searching for the simple and reliable tools to guide us in rapid assessment and selection of the patients with penumbral “tissue-at-risk” which would benefit from timely reperfusion. Current widely used clinical and imaging scores are (this is not all inclusive list): CT and MRI ASPECTS, THRIVE, NIHSS, recently published HIAT2. MRI and CT perfusion are commonly mentioned, but not readily used methods in a clinical practice. 

In a period of 5 years, Kamalian and collegues, from Mass. General retrospectively analyzed prospectively acquired data for the 45 patients with M1 occlusion. All of patients had NCCT followed by CTA. Mean time to DWI and MR perfusion was about 5 hours as per institution protocol. Two non radiologist blinded to all correlative clinical and other imaging data, evaluated scans for percentage of insular infarction with substantial interobserver agreement for the percent insula ribbon infarction (PIRI) ratings which represented combined effect of infarction and pial collateral flow. PIRI score was stratified “0”=normal, “1”<25%, “2”=25-49%, “3”=50- 74%, and “4”≥75% insula involvement. Percent-mismatch-loss was calculated as an outcome measure. They also compared this score with NIHSS score, DWI ASPECT score, DWI infarct volume, or CTA-collateral score. 

Optimal operating PIRI score was found to be 1 with PIRI score >1 and patient’s age were the best independent predictor of large mismatch loss. Also each additional step increase in PIRI score had strong correlation with the further mismatch loss. 

Field of endovascular neurointervention is at flux; several recent studies were discouraging (execution, patent selection and devices used can be questioned). New, better and safer devices were recently introduced, Therefore, the insula score may help to further stratify patients with small infarcts who are likely to undergo significant infarct extension and in whom rapid treatment would be expected to yield the greatest benefit.