Ultrasound Therapy Disrupts Blood-Brain Barrier
Study terminated after first patient showed dye leakage in MRI scans
FRIDAY, May 12 (HealthDay News) -- A study testing wide-field low-frequency ultrasound to improve cerebral blood flow was terminated after the first patient developed what appeared to be a subarachnoid hemorrhage, according to a report published online April 27 in Stroke. Although the abnormality quickly resolved, the study authors suggest that ultrasound may temporarily disrupt the blood-brain barrier.
Andreas Hetzel, M.D., and colleagues from the University of Freiberg, Germany, initiated the study to determine whether transcranial application of wide-field low-frequency ultrasound could improve cerebral hemodynamics in patients with small vessel disease. This technique has previously been used in combination with thrombolytic agents or nitric oxide to improve cerebral bloodflow, but caused hemorrhaging in a recent study.
Four patients with severe small vessel disease were originally assigned to the treatment, but immediately after a 60-minute insonation of the first patient, magnetic resonance imaging showed frontoparietal extravasation of the contrast agent. The patient remained asymptomatic and the effect did not occur in a second trial, but the study was terminated for safety reasons.
"Though the transient blood-brain barrier disruption could also bear a therapeutic potential by facilitating drug delivery of macromolecules, it has to be tentatively regarded as a negative effect of wide-field low-frequency ultrasound on the cerebral endothelium outweighing any potential benefit on thrombolysis or cerebral perfusion," the authors conclude.