Cerebral bleeding after treatment also occurred on the opposite MDV3100 cost side of the brain infarction, suggesting a causal link to the substantially higher energy and lower frequency of the “sonothrombolysis probe” compared with the energy of diagnostic US probes. In vivo experiments evaluating the therapeutic efficacy and safety of using highly energetic, low-frequency (20 kHz) US in treating rats with an embolic MCA occlusion showed

an increased incidence of cerebral edema [24] and [25], thus indicating the unsuitability of this kind of US for clinical use. So far, “diagnostic” transcranial US remains the only form of US appropriate for sonothrombolysis. Skoloudik et al. [7] performed a

pilot study on 9 patients who had suffered an AIS with acute MCA or basilar artery occlusion and undergone endovascular sonothrombolysis within an 8-h time window from symptom onset. For this purpose, a 3F microcatheter with a US probe of 2.05–2.35 MHz was used. Complete recanalization at the end of treatment was achieved in one third of patients, and partial recanalization occurred in an additional 44% of patients at the end of the procedure. At admission, the National Institutes of Health Stroke Scale (NIHSS) scores were in the range of 10–33 (median, 19.0). At 3 months, 4 (44%) patients were functionally independent (modified ZD1839 supplier Rankin Scale [mRS] score, 0–3; median mRS score, 4). No sICHs occurred for 24 h after endovascular sonothrombolysis

until a control computed tomography (CT) scan at 24 h. These researchers concluded that this endovascular system might serve as a new treatment option for patients suffering from acute stroke. The thrombolytic effect of US has generally been regarded as a tool for improving recanalization. However, as several US follow-up studies have shown, reocclusion of a vessel after recanalization can occur in 20% or more (up to 29%) of patients after rtPA treatment [1] and [26]. Sawaguchi et al. [27] recently 4��8C reported interesting results from a novel use of US treatment in AIS. They found that continuous US (500 kHz, 0.72–0.28 W/cm2) significantly suppressed thrombus growth in vitro. Based on their findings, these researchers suggested low-intensity, low-energy US as a possible simple and safe tool to prevent reocclusion of intracranial vessels after rtPA treatment. Determining the most efficient US settings for sonothrombolysis is complicated by the fact that there is a tremendous number of possible combinations of its parameters. Wang et al. [28] presented results from an in vitro experiment for the systematic and rapid evaluation of the thrombolytic effect of 500-kHz US as the ultrasonic spatial intensity increased from 0.1 to 0.7 mW/cm2.