Potential for Transcranial Laser or LED Therapy to Treat Stroke, Traumatic Brain Injury, and Neurodegenerative Disease
Margaret A. Naeser, Ph.D., L.Ac.,1,2 and Michael R. Hamblin, Ph.D.3,4,5
“In an early study with TLT, (transcranial light therapy,) to treat acute stroke in rats, significant beneficial results were obtained whether TLT was applied in a bilateral, ipsilesional or contralesional manner.12 TLT (808 nm) significantly improved recovery ( p < 0.01) at 3 weeks following ischemic stroke when treated once, at 24 h
post-stroke (contralesional; power density, 7.5mW/cm2 to brain tissue).9 The number of newly formed neuronal cells, assessed by double immunoreactivity to BrdU and tubulin isotype III, as well as migrating cells (doublecortin immunoreactivity), was significantly elevated in the ipsilesional SVZ. There was no significant difference in the stroke lesion area between control and laser-irradiated rats. The authors suggested that an underlying mechanism for the functional benefit post-TLT was possible induction of neurogenesis. Other
studies have also suggested that because improvement in neurologic outcome may not be evident for 2–4 weeks in the post-stroke rat model, delayed benefits may be caused, in part, by induction of neurogenesis and migration of neurons.13,14
A recent study with embolized rabbits showed a direct relationship between level of cortical fluence (energy density, J/cm2) delivered, and cortical ATP content.15 Five minutes following embolization (right carotid), rabbits were exposed
1VA Boston Healthcare System, West Roxbury, Massachusetts.
2Department of Neurology, Boston University School of Medicine, Boston, Massachusetts.
3Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts.
4Department of Dermatology, Harvard Medical School, Boston, Massachusetts.
5Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts.
Photomedicine and Laser Surgery
to 2 min of NIR TLT using 808-nm laser on skin surface, posterior to bregma at midline. Three hours later, the cerebral cortex was excised. Use of continuous wave (CW) TLT (7.5mW/cm2, 0.9 J/cm2) resulted in a 41% increase in cortical ATP. Use of 100-Hz pulsed wave (PW) TLT (37.5mW/ cm2, 4.5 J/cm2) resulted in a 157% increase in cortical ATP.
Surprisingly, the increased cortical ATP level of 157% was higher than that measured in naive rabbits that had never suffered stroke. The authors suggested in future studies, greater improvement might be achieved by optimizing length of treatment, and mode of treatment (PW, perhaps at 100 Hz).
TLT has been shown to significantly improve outcome in human acute stroke patients, when applied at *18 h poststroke, over the entire surface of the head (20 points in 10/20 EEG system) regardless of stroke location.16–18
Significant improvements ( p < 0.04) were observed in the moderate and moderate–severe stroke patients only (n = 434), who received the real laser protocol (vs. sham), but not in severe stroke patients.17
To date, there are no TLT studies to treat chronic stroke patients. The use of laser light to stimulate acupuncture
points on the body (instead of needles) to treat paralysis in chronic stroke patients ( > 10 months post-stroke onset) has resulted in similar levels of improvement, following a series of 20 or 40 laser (or needle) treatments.19–21 A 20-mW, 780- nm, CW laser with 1-mm diameter aperture (Unilaser,
Denmark) was used (51–103 J/cm2 per point). Overall, 5/7 (71.4%) of the patients showed improvement, with an increase of 11–28% in isolated, active range of motion for shoulder abduction, knee flexion, and/or knee extension.
The two patients who showed no improvement had severe paralysis, with results similar to TLT results with severe, acute stroke patients.17 Therefore, stroke patients with paralysis improved when the paralysis was not severe, although a reduction in spasticity has been observed in severe cases (M.A.N., personal observation). Stroke patients with only mild or moderate hemiparesis (including only hand paresis) appear to have the best potential for improvement.
On brain CT scan, these mild–moderate cases have smaller areas of infarction adjacent to the body of the lateral ventricle, than those with severe paralysis in whom the lesion is often adjacent to the body of the lateral ventricle, closer to the SVZ, possibly impeding potential for neurogenesis. Depth of white matter lesion appears to be more important regarding potential for recovery than is the overall size of the cortical lesion.19–22 (See also: www.bu.edu/naeser/acupuncture)”