Influence of the number of passes of Stent-Retriever on the occurrence of parenchymal hematomas in stroke patients undergoing thrombectomy

•There is a greater frequency of parenchymal hematomas when more than three mechanical thrombectomy passes are performed.•The incidence of parenchymal hematomas shoots up when 6 or more passes are performed.•When 6 or more passes are performed, 30% of the patients still achieve a good clinical evolution after three months.