NEW YORK (Reuters Health) — Sonothrombolysis with recombinant tissue-type plasminogen activator (rt-PA) has a beneficial effect in patients with middle cerebral artery main stem occlusion, according to a report in the May issue of Stroke.

"Sonothrombolysis is a new treatment approach for stroke," Dr. Jurgen Eggers from Asklepios Hospital Hamburg North, Germany told Reuters Health. "It improves recanalization and short-term outcome and (shows) a strong tendency toward improved long-term outcome."

Dr. Eggers and colleagues investigated the effect of transcranial color-coded sonography (TCCS)-guided pulsed wave ultrasound on recanalization and outcome of 37 patients who also underwent standard thrombolytic therapy with rt-PA for acute occlusion of the main stem of the middle cerebral artery. The subjects were randomized to 1 hour of transcranial continuous insonation with a 1.8-MHz probe or to a control group.

Recanalization was faster in the ultrasound group than in the no-ultrasound group beginning after 20 minutes, the authors report, and recanalization rates after 1 hour were higher in the ultrasound group (57.9%) than in the control group (22.2%).

There were no differences between the groups in restitution of flow 24 hours after symptom onset.

Twice as many patients in the ultrasound group as in the no-ultrasound group showed improvement of at least 4 points in the NIH Stroke Scale (NIHSS) at days 1 and 4, the researchers note, and NIHSS values at day 1 and day 4 had improved to a significantly greater extent in the ultrasound group than in the no-ultrasound group.

By 90 days, favorable functional outcomes (as defined by Barthel Index scores of at least 95) were more frequent in the ultrasound group, but there were no significant differences in death rates or modified Rankin scores between the groups at 90 days.

There were more cases of symptomatic and asymptomatic intracranial hemorrhage in the ultrasound group than in the no-ultrasound group, the investigators say, and there was a tendency toward more severe hemorrhagic transformations in the ultrasound group, but no hemorrhages occurred outside the infarction area.

"The nonsignificant elevation of bleeding rate in this study may be result of improved recanalization (reperfusion trauma)," Dr. Eggers said.

"Currently I am going to launch a study with sonothrombolysis alone in subjects with contraindication for thrombolysis with t-PA," Dr. Eggers added. "So far, sonothrombolysis is performed using 'diagnostic' ultrasound transducers, but the next step should be the development of transducers designed primarily for this purpose."

Stroke 2008;39:1470-1475.