Mechanical thrombectomy in patients with M1 occlusion and NIHSS score ≤5: a single-centre experience

Background: The recent success of several mechanical thrombectomy trials has resulted in a significant change in management for patients presenting with stroke. However, it is still unclear how to manage patients that present with stroke and low National Institutes of Health Stroke Scale (NIHSS) <= 5. We sought to review our experience of mechanical thrombectomy in patients with low NIHSS and confirmed M1 occlusion. Methods: We retrospectively analysed our prospectively maintained database of all patients undergoing mechanical thrombectomy between January 2008 and August 2016. We identified 41 patients with confirmed M1 occlusion and low NIHSS (<= 5) on admission to our hospital. We collected demographic, radiological, procedural and outcome data. Results: The mean age of patients was 72 +/- 14, with 20 male patients. Associated medical conditions were common with hypertension seen in similar to 80%. Just over 50% presented with NIHSS 4 or 5. The average ASPECTS score on admission was 8.8 (range 6-10), and the average clot length 10 mm. Angiographically Thrombolysis in Cerebral Infarction (TICI) >= 2b was obtained in 87.8% of patients. 7 patients had haemorrhage on follow-up, 2 of which were symptomatic. Of 40 patients with 90-day follow-up, 75% had modified Rankin Scale (mRS) score 0-2. There were 3 deaths at 90 days. Conclusions: Mechanical thrombectomy in patients with low NIHSS and proximal large vessel occlusion is technically possible and carries a high degree of success with good safety profile. Patients with low NIHSS and confirmed occlusion should be considered for mechanical thrombectomy.