Laser therapy shows promise in rabbit stroke study
26 May 2004
Stroke2004; [Early online publication]
Research in rabbits supports the potential for transcranial infrared laser therapy to be developed as a novel treatment for embolic stroke.
“Recent studies have shown that laser-generated infrared radiation (ie. photon or light energy) is able to penetrate various tissues, including the brain, and modify function,” observe Paul Lapchak (University of California, San Diego, USA) and colleagues. In particular, there have been reports that laser treatment may reduce lesion size in the heart after myocardial infarction in rats.
Noting that there are important similarities between cardiac and cerebral ischemia, the scientists investigated whether transcranial laser therapy could improve the clinical outcomes of embolic stroke.
For the study, small clot embolic stroke was induced in male New Zealand White rabbits by injecting microclots into the common carotid artery via a catheter. One, 6, or 24 hours after embolization, the animals were treated with transcranial laser therapy, which involved placing a probe directly on the skin surface above the brain, and applying infrared energy for a duration of 10 minutes. The dose of laser treatment was designed to penetrate the rabbit skull and brain to a depth of 2.5-3 cm, encompassing the majority of the brain. Neurologic and behavioral evaluation was performed 24 hours after embolization, and again up to 21 days later.
Compared with a control group of rabbits with induced microembolic stroke that did not receive laser therapy, the stroke dose required to produce significant neurologic deficits was more than doubled if laser treatment was initiated within 6 hours of embolization. This correlated with a significant improvement in behavioral outcomes. However, no such benefit was observed with laser treatment at 24 hours.
Furthermore, early laser therapy produced a durable improvement in stroke outcomes that was still evident 21 days after treatment.
“Overall, our preclinical study indicates that transcranial laser therapy is a promising candidate for development as a treatment for acute stroke,” Lapchak et al conclude.