More study on prevention and treatment strategies for this devastating complication is the next step, one expert contends.


Malignant brain edema has a substantial negative impact on the outcomes of mechanical thrombectomy, according to a study published online recently ahead of print in the Journal of NeuroInterventional Surgery. Internal carotid artery (ICA) occlusions and poor collaterals were identified as predictors of the complication.


Increasing understanding of how thrombectomy may relate to malignant brain edema is important in light of recent efforts to expand the population of stroke patients who may benefit from this intervention, W. Taylor Kimberly, MD, PhD (Harvard Medical School and Massachusetts General Hospital, Boston, MA), who was not involved in the study, told Neurovascular Exchange. The risk that thrombectomy may contribute to brain edema, he added, is of particular concern in patients with low ASPECTS scores.


The new study, Kimberly commented, is “an important piece to the puzzle in terms of understanding relationship of thrombectomy and edema. Previously, there have been conflicting reports in the literature. Some suggest that thrombectomy or reperfusion can lead to worsening edema. Other studies have suggested that thrombectomy or reperfusion can reduce edema.” Notably, this study focused solely on the thrombectomy population, he pointed out.


Edema ‘Leverages a Severe Penalty’ on Recovery


Xianjun Huang, MD (Yijishan Hospital of Wannan Medical College, Wuhu, China), and colleagues evaluated 130 consecutive patients (mean age 68.6 years; 50% male) who underwent mechanical thrombectomy for anterior circulation large-vessel occlusion stroke. Of these patients, 26.9% developed malignant brain edema, defined as a midline shift of ≥ 5 mm on follow-up imaging within 72 hours after thrombectomy.


Overall, 80% of patients attained an mTICI score of 2b-3. Among these patients, 23.1% went on to develop malignant brain edema. After controlling for confounders, predictors of malignant brain edema were identified as the presence of ICA occlusions and collateral status.


Predictors of Malignant Brain Edema


OR (95% CI)

P Value

ICA Occlusion

3.75 (1.17-12.01)


Collateral Score Grade 1 vs 0

0.73 (0.19-2.75)


Collateral Score Grade 2 vs 0

0.13 (0.02-0.82)



Patients who developed malignant brain edema were less likely to develop functional independence, defined as an mRS 0-2 (OR 7.83; 95% CI 1.73-35.43). They also had a significantly greater 90-day mortality rate (OR 7.96; 95% CI 2.27-27.85) than patients without this complication.


“Thrombectomy is now the standard of care, but . . . if a patient develops brain edema, it really leverages a severe penalty on their recovery,” said Kimberley. “This means there is still room for additional strategies and interventions to help patients recover from a stroke.”


Being able to predict who might develop severe edema, he continued, is useful clinically because “it can help guide decisions around decompressive craniectomy and upcoming or future management of edema in a given patient,” he explained.


Medical and surgical strategies for the prevention and treatment malignant brain edema are currently being evaluated. This is an area of research in which Kimberley himself is active.


He noted that this study is retrospective and only included thrombectomy patients. “Ideally to answer this question, it would be a comparison [with] a control or nonthrombectomy patient population,” Kimberly suggested. “The authors acknowledge that as a limitation, and there are randomized controlled trials to address this question that are underway.”




Huang X, Yang Q, Shi X, et al. Predictors of malignant brain edema after mechanical thrombectomy for acute ischemic stroke. J NeuroInterv Surg. 2019;Epub ahead of print.