Factors associated with timing of early neurological improvement after thrombolysis for ischaemic stroke

Early neurological improvement (ENI) after fibrinolysis for ischaemic stroke is strongly associated with recanalization and favourable outcome. However, it remains unknown why some patients recover within the first hour after treatment (very ENI, VENI) whereas others recover later within 24 h.The factors associated with the timing of ENI were assessed.Consecutive stroke patients treated with intravenous recombinant tissue plasminogen activator (rt-PA) within 4.5 h after onset in four stroke centres of our geographical area were retrospectively studied. VENI assessed at 1 h and ENI assessed at 24 h post-treatment were defined by National Institutes of Health Stroke Scale (NIHSS) improvement by 40% from baseline.Of 421 patients, 65 (15%) had VENI and 110 (26%) had ENI. Patients with VENI had significantly lower serum creatinine level than patients with ENI (79 ± 19 vs. 91 ± 35 μmol/l; P = 0.01). After adjustment for age, sex, baseline NIHSS, hypertension and blood glucose level, patients with low serum creatinine level were more likely to have VENI (lowest tertile, odds ratio 3.8, 95% confidence interval 1.5-9.7; intermediate tertile, odds ratio 1.8, 95% confidence interval 0.8-4.3; P for trend <0.01). VENI patients were as likely as ENI patients to have a modified Rankin scale score ≤2 at 3 months.Low serum creatinine levels are associated with VENI, suggesting that swiftness of the efficacy of rt-PA or of neurological recovery may depend on renal function.