Normal findings on pretreatment transcranial ultrasound in patients treated with sonothrombolysis

In populations with a high (≥14) median National Institute of Health Stroke Score (NIHSS), a normal finding of Thrombolysis in Brain Ischemia grade 5 (TIBI 5) in the artery of interest has been reported to be an unusual finding when transcranial ultrasound is performed during thrombolysis. In such instances, a stroke mimic can be suspected, but there are alternative pathophysiological explanations. In this case series, the median NIHSS was relatively low (5), and 33% (6/18) of the patients treated with thrombolysis had TIBI 5 in the artery of interest at the time of treatment initiation. These 6 patients had normal findings on the computerized tomography angiography. Only 33% (2/6) of these patients were stroke mimics, the remaining had either lacunar (n = 2) or cortical strokes (n = 2). These cortical stroke patients probably had a pretreatment recanalization marked by partial symptom regression before treatment onset. Compared to patients with TIBI <5 at baseline, the patients with TIBI 5 at baseline tended to be younger (p = 0.19, Mann-Whitney test) and more often have lacunar syndrome (p = 0.18, χ(2) test). Thus, among patients treated with thrombolysis and with a low median NIHSS, a finding of TIBI 5 is not unusual. This does not mean that the patient has a stroke mimic per se, and it tends to be more common among patients with lacunar syndrome than among patients with cortical syndromes.