Effects of Low-Level Laser Therapy on Painful Diabetic Peripheral Neuropathy: A Pilot Study

Electrotherapeutic modalities, including Low-Level Laser Therapy (LLLT), can potentially treat painful DPN.

Number of subjects: Eight participants aged 40-70 with T2D and painful DPN were recruited. The study is ongoing, with a goal to recruit 12 more participants.

Michigan Neuropathy Screening Instrument (MNSI), Visual analog scale (VAS), and Berg balance scale (BBS) were used to assess nerve function, pain levels, and balance before and after the intervention. Additionally, gait parameters were assessed by evaluating gait velocity, step length, stride length, and cadence using Gait Rite Mat. The Multiwave Lock System (MLS) Laser was used to administer the LLLT. .Intervention includes 12 sessions of Level LLLT with a dosage of 3.1 J/cm² on fibular head, tarsal tunnel, and dorsum of the foot over the period of 4 weeks. The fibular head and tarsal tunnel were treated for 1 minute each with 103.536 Joules, a frequency of 700 Hz, and an intensity of 100% in an area of 56 cm². The dorsum of the foot was treated for 6 minutes with 621.216 Joules, a frequency of 700 Hz, and an intensity of 100% in an area 150 cm². The treatment time was 8 minutes per leg and 16 minutes total per subject. Data was analyzed using the Wilcoxon sign rank test. 

The data analyzed was collected from 4 females and 4 males with T2D and painful DPN (n=8). The mean age of the subjects was found to be 62.65 ± 10.81 years. Results of Wilcoxon Signed Rank Test indicated statistically significant reductions in pain

(6.05 vs 1.71 cm; p = 0.001) before and after the intervention. Results were insignificant for the rest of the outcome variables in this small sample. The data was analyzed further to explore the minimal clinically important difference (MCID) and determine if the laser intervention benefited the patient. A change in pain score of 1-1.9 is considered beneficial from the patient’s perspectives . Our study reported a change of 4.34 cm; therefore, the MCID value was achieved, underscoring the significance of this threshold in indicating meaningful improvements for individuals with painful DPN. 

LLLT with MLS Laser reduced pain in T2D patients with painful DPN. We are positive that after recruiting and analyzing the data from all twenty subjects, we will further elucidate the efficacy of LLLT in addressing painful DPN, including its impact on additional outcome measures such as balance and gait parameters. 

From a physical therapy (PT) perspective, the significant reduction in pain through LLLT suggests promising clinical implications for managing painful DPN in individuals with T2D. It could enhance comfort and mobility in PT interventions for chronic neuropathic pain. Larger studies are needed to validate and refine treatment protocols.