Thrombectomy for Small-Artery Occlusions with the Small-Diameter Stent Retriever, Tron Fx 2 mm × 15 mm: A Case Series

OBJECTIVE: The safety and efficacy of thrombectomy for small-artery occlusions is still controversial. In April 2019, Tron Fx, a stent retriever with an expansion diameter of 2 mm, became reimbursed by health insurance in Japan. We report on cases of thrombectomy for small-artery occlusions performed using this device in seven patients. METHODS: The subjects were seven patients who underwent thrombectomy between July 2019 and June 2020 using Tron Fx with 2 mm in diameter. We analyzed clinical results including recanalization and complications. RESULTS: The mean age of the seven patients was 80.1 years, and the subjects included six men. The sites of occlusion were the middle cerebral artery M2 (n = 4), M4 (n = 1), anterior cerebral artery A2 (n = 1), and A3 (n = 1). One of the seven patients had an M2 occlusion that was formed during coil embolization for a ruptured cerebral aneurysm. In five cases, four cases were of primary occlusion and one case was of emboli into a new territory, treating with only Tron Fx 2 mm resulted in thrombolysis in cerebral infarction (TICI) 2b–3 in four cases. There was one case of grade 0, which was M4 occlusion. Finally, TICI 2b–3 were achieved in six of seven cases. No symptomatic intracranial hemorrhage occurred. Symptoms improved in five of six patients, excluding a vascular occlusion that occurred during surgery. CONCLUSION: Tron Fx with 2 mm diameter can be used safely for small-artery occlusion. The introduction of Tron Fx with 2 mm diameter may contribute to expand indications for thrombectomy for small-artery occlusions.