Distribution and prognosis of acute ischaemic stroke with negative diffusion-weighted imaging

To examine the distribution and prognosis among patients with diffusion-weighted imaging (DWI)-negative acute ischaemic stroke (AIS) and explore the differences between mild (National Institute of Health Stroke Scale (NIHSS) score ≤5) and major (NIHSS score >5) ischaemic stroke in DWI-negative patients.

Patients with AIS with baseline DWI from the Third China National Stroke Registry (CNSR-III), based on a prospective, observational, multicentre cohort study, between August 2015 and March 2018, were included. Patients were classified into negative and positive DWI groups depending on the existence of acute lesions on DWI.

Among 12 026 patients who had an ischaemic stroke, 932 (7.7%) had negative DWI. As the NIHSS score increased, the proportion of patients with DWI-negative AIS gradually decreased. Negative DWI was associated with a decreased risk of stroke recurrence (HR 0.63, 95% CI 0.49 to 0.82), combined vascular events (HR 0.72, 95% CI 0.56 to 0.92), mortality (HR 0.60, 95% CI 0.36 to 0.995) and poor functional outcomes (OR 0.57, 95% CI 0.43 to 0.76) within 1 year in all patients. Similar associations were observed in patients with mild AIS (p<0.05 for all) but not in patients with major AIS, excluding poor functional outcomes (OR 0.47, 95% CI 0.28 to 0.81).

The proportion of patients with DWI-negative AIS gradually decreased as the NIHSS score increased, and negative DWI was mainly observed in patients with mild AIS. Negative DWI was associated with a better prognosis for all patients with AIS. However, these associations were significant for mild AIS but not for those with major AIS.