Delphi Consensus on Early Neurologic Improvement after Mechanical Thrombectomy

Early neurologic improvement (ENI) following mechanical thrombectomy (MT) has been a topic of substantial interest. The literature has more than 40 ENI definitions, yet no consensus has been reached. In this Delphi study, we sought to investigate experts' perspectives on the available ENI definitions and determine whether a consensus can be achieved.

The Delphi approach assessed experts' perspectives on available ENI definitions. Following a systematic literature review, the first survey round was prepared and sent to 20 experts using a Web-based anonymous survey platform (qualtrics.com). The first round of questions was publicly shared on the letsgetproof.com platform to gather perspectives of neurointerventionalists worldwide on ENI definitions. Expert and volunteer answers formed the basis of subsequent rounds, in which closed-ended questions were sent only to experts. Consensus was defined as an agreement of ≥70% for binary closed-ended questions and ≥50% for closed-ended questions with >2 response options.

Experts completed 3 survey rounds. They recognized that the heterogeneity in ENI definitions is the most critical factor limiting the use of ENI in clinical practice and stroke research. All experts acknowledged that stroke physicians need a standardized universal ENI definition. Consensus was reached on the notion that a unified ENI definition should focus on predicting functional independence at 3 months. They agreed that NIHSS improvement of ≥8 points at 24 hours could serve as the unified ENI definition. They acknowledged that incorporating prestroke comorbidities, occlusion location, baseline NIHSS scores, and procedure-related parameters would complicate the ideal ENI definition and limit its use in clinical settings. The experts could not reach a consensus on the potential utility of ENI as a primary end point in MT trials.

In our Delphi analysis, experts agreed on an ENI definition. They did not endorse using different ENI criteria for patients with comorbidities, posterior circulation occlusions, or high baseline NIHSS scores. Further prospective studies are needed to validate or refine ENI definitions and to address the paucity of data on the prognostic utility of ENI in specific clinical scenarios.