Effect of ultrasound treatment on brain edema in a traumatic brain injury model with the weight drop method.

BACKGROUND: For the treatment of traumatic brain edema, an efficient modality has not yet emerged. There have been many studies to date which have reported the employment of low-frequency ultrasound for blood-brain barrier disruption (BBBD). However, the authors have observed that low-intensity ultrasound increases water permeability without cellular damage in cartilage cells. We have therefore attempted to observe the effects of applying this low-intensity ultrasound to an experimental animal model. METHODS: A traumatic brain injury rat model was established according to the weight drop method developing the traumatic brain edema. The degree of BBBD was measured by the changes in the water content and spectrophotometric absorbance of Evans blue dye in the cerebrum after low-frequency ultrasound. RESULTS: The cerebral water content levels showed that the BBBD gradually increased after impact and thereafter decreased after 6 h. After low-frequency ultrasound exposure, the values of water content and spectrophotometric absorbance of Evans blue dye were the lowest at 0 h, and were increased at 2 and 5 h of ultrasonic exposure (after impact). CONCLUSION: We suggest that traumatic brain edema in the rat model may be alleviated by low-frequency ultrasound, and low-frequency ultrasound might be proposed as a novel treatment modality for brain edema.