Neurological Effects of Therapeutic Laser
One of the areas of laser therapy that is rather interesting and promises significant potential for healing is application of therapeutic laser to neurological conditions. In this article, I will present a review of scientific studies relative to neurological effects of laser and discuss some of the more promising applications.
Therapeutic laser has been studied for numerous neurological conditions that include:
- Stroke (including acute embolic stroke, ischemic stroke)
- Traumatic brain injury
- Neurodegenerative diseases such as Parkinson’s Disease
- Trigeminal neuralgia
- Post-herpetic neuralgia (PHN)
- Cerebral palsy
- Spinal cord injuries
- Peripheral nerve regeneration
- Major depression
Lapchak et al applied infrared light therapy to rabbits that suffered acute embolic stroke. Light therapy was applied transcranially 6 to 12 hours post embol-ization with continuous wave and pulsed waves. Behavior analysis was performed 48 hours after ischemic stroke. The results demonstrated that the pulsed mode IR light therapy resulted in significant clinical improvement when administered 6 hours following embolic strokes in rabbits.1
Oron et al studied the effects of GaAs laser irradiation on adenosine triphosphate (ATP) production in normal human neural progenitor cells. Tissue cultures were treated with the GaAs laser and ATP levels were determined at 10 minutes post laser application. The quantity of ATP in the treated cells was significantly higher than the non-treated group. The application of laser to normal human neuronal progenitor (NHNP) cells significantly increases ATP production. This may explain the beneficial effects of LLLT in stroked rats.2
Naeser studied the effect of laser acupuncture to treat paralysis in stroke patients and to examine the relationship between anatomical lesion sites on CT scan and the potential for improvement following laser acupuncture treatments. Seven stroke patients (five men and two women; aged 48 to 71) were admitted to the study. Five cases had a single left hemisphere stroke and two cases had a single right hemisphere. Five patients were treated for residual arm or leg paralysis. They exhibited greatly reduced arm and leg power with greatly reduced or absent voluntary isolated finger movement. Two cases, with good arm and leg power but exhibiting mildly reduced isolated finger movement, were treated only for hand paresis.
CT scans were obtained on all patient at least three months post stroke. Six patients began receiving the laser acupuncture treatments during the chronic phase post stroke (10 months to 6.5 years). These intervals are beyond the spontaneous recovery period of up to six months post stroke.3,4 One hand paresis case began receiving treatments during the acute phase post stroke (one month post stroke). Because all but one patient were beyond the spontaneous recovery period, each patient served as his/her own control. No sham laser treatments were administered. None of the stroke patients was receiving physical therapy or occupational therapy treatments during the course of the laser acupuncture treatments. The use of low-level laser for long-term treatment is especially desirable for chronic stroke patients with hand paresis. The patient can be trained to treat him/herself at home, using an inexpensive 5mW red-beam diode laser pointer and a microamps TENS device.
This is the first study to examine the effect of low-level laser therapy on acupuncture points to treat paralysis in stroke patients where the lesion location was known for each patient. Results suggest that low-level laser therapy on acupuncture points is effective to help reduce the severity of paralysis in stroke patients—especially those with mild-to-moderate paralysis. The treatments should be initiated as soon as possible post stroke, even within 24 hours post stroke. A comprehensive rehabilitation program of physical therapy, occupational therapy, plus needle and/or laser acupuncture is recommended.5
Lampi et al conducted a prospective, intention-to-treat, multicenter, international, double-blind trial (Neurothera® Effectiveness and Safety Trial-1; NEST-1) involving 120 ischemic stroke patients treated, randomized in a 2:1 ratio, with 79 patients in the active treatment group and 41 in the sham (placebo) control group. Only patients with baseline stroke severity scores of 7 to 22 were included, as measured by the National Institutes of Health Stroke Scale (NIHSS). Patients who received tissue plasminogen activator were excluded. Outcome measures were the patients’ scores on the NIHSS, modified Rankin Scale (mRS), Barthel Index, and Glasgow Outcome Scale at 90 days after treatment.
The primary outcome measure, prospectively identified, was successful treatment as documented by NIHSS. This was defined as a complete recovery at day 90 (NIHSS 0 to 1), or a decrease in NIHSS score of at least 9 points (day 90 versus baseline) and was tested as a binary measure (bNIH). Secondary outcome measures included mRS, Barthel Index, and Glasgow Outcome Scale. Primary statistical analyses were performed with the Cochran-Mantel-Haenszel rank test, stratified by baseline NIHSS score or by time to treatment for the bNIH and mRS. Logistic regression analyses were conducted to confirm the results.
“A post-hoc analysis of 434 patients who suffered moderate to moderately severe strokes showed a favorable outcome in 51.6% of patients in the TLT group compared to 41.9% of patients in the sham group. This 9.7% treatment effect was statistically significant (p-value 0.044).”
Mean time to treatment was >16 hours (median time to treatment 18 hours for active and 17 hours for control). Time to treatment ranged from 2 to 24 hours. More patients (70%) in the active treatment group had successful outcomes than did controls (51%) as measured prospectively on the bNIH (P=0.035 stratified by severity and time to treatment; P=0.048 stratified only by severity). Similarly, more patients (59%) had successful outcomes than did controls (44%) as measured at 90 days with a binary mRS score of 0 to 2 (P=0.034 stratified by severity and time to treatment; P=0.043 stratified only by severity). Also, more patients in the active treatment group had successful outcomes than controls as measured by the change in mean NIHSS score from baseline to 90 days (P=0.021 stratified by time to treatment) and the full mRS (“shift in Rankin”) score (P=0.020 stratified by severity and time to treatment; P=0.026 stratified only by severity). The prevalence odds ratio for bNIH was 1.40 (95% CI, 1.01 to 1.93) and for binary mRS was 1.38 (95% CI, 1.03 to 1.83), controlling for baseline severity. Similar results held for the Barthel Index and Glasgow Outcome Scale. Mortality rates and serious adverse events (SAEs) did not differ significantly (8.9% and 25.3% for active 9.8% and 36.6% for control, respectively, for mortality and SAEs).6
The NEST-1 study indicates that infrared laser therapy has shown initial safety and effectiveness for the treatment of ischemic stroke in humans when initiated within 24 hours of stroke onset. A larger confirmatory trial to demonstrate safety and effectiveness is warranted.