Much emphasis is being placed on early stroke diagnosis in the acute care setting, especially being able to pick up signs of early ischemic changes on CT scan. These can include loss of demarcation of subcortical structures, sulcal effacement and loss of gray-white matter junction differentiation. Using these early ischemic signs to detect viable tissue during acute ischemic stroke is becoming more popular as these assessments are rapidly done, rather than pursuing lengthier perfusion imaging procedures. There is no consensus on the exact interpretation and meaning of early ischemic findings and the significance of these findings as they are related to long-term outcome and thus the group out of Emory University decided to further pursue whether there are beneficial or detrimental signs on non-contrast CT that can indicate future outcome.
The group selected 108 patients that underwent intra-arterial therapy during a three year period at their institution and found that signs of isolated sulcal effacement (ISE- defined as the presence of sulcal effacement with an intact gray-white matter junction) was present in eight patients (7.4%) with an average age of 55 years and average NIHSS of 16. 5 of these patients had a MCA-M1 occlusions and 3 had an ICA-T occlusion. The areas of ISE were correlated with CTA scans showing dilated leptomeningeal vessels within the areas of effacement and perfusion scans showing that there was a normal to increased CBV and prolonged Tmax in these areas signifying areas of collateral flow that may be at risk. The group was able to achieve TICI 2b-3 reperfusion in all patients and follow up imaging later confirmed that in all cases, there was no infarct in the ISE area on the patients’ initial imaging and long term outcome showed that five of the patients had an mRS of 0-2 at 3 months.
The group’s data points toward not only good outcome for early recanalization in patients with ISE but also provides some support for the idea that perfusion imaging may not even be required in such cases as a clinical presentation of large vessel occlusion in conjunction with a scan of ISE (with good ASPECTS score) may be enough to show that there is tissue at risk. Rapid recanalization would support the often quoted mantra that “time is brain” and further lead to improved outcome in these patients. The work is also supporting the idea that isolated sulcal effacement is actually a sign of robust collateral flow and not a sign of parenchymal injury as was once thought. Of course, all collaterals are not created equal and this may explain why 3 of the 8 patients still did not have a good outcome (mRS >2) but perhaps larger observational studies are in order to provide better correlation.