The Use of Photobiomodulation in the Treatment of Spasticity After Stroke.

Condition(s) studied

Investigational drug(s) / intervention(s)

Photobiomodulation Therapy: Photobiomodulation (PBM)-formerly referred to as low-level laser therapy (LLLT) or cold laser therapy-is a non-invasive, non-thermal therapeutic modality that employs light in the red to near-infrared spectrum (typically spanning wavelengths from approximately 600 nm to 1,100 nm) to elicit beneficial biological responses in target tissues. The underlying mechanism of action is primarily photochemical rather than photothermal: photons delivered to the tissue are absorbed by endogenous chromophores, most notably cytochrome \*c\* oxidase (CCO), a key enzyme in the mitochondrial electron transport chain. This absorption transiently increases mitochondrial membrane potential, augments adenosine triphosphate (ATP) synthesis, and modulates the generation of reactive oxygen species (ROS). These primary mitochondrial events subsequently trigger a cascade of secondary intracellular signaling pathways-including the activation of transcription factors such as nuclear factor kappa-B (NF-κB) and hypox

Placebo PBM: Application of transcutaneous PBM therapy - device switched off- to the gastrocnemius muscles

Standard Multidisciplinary Rehabilitation Program for Spasticity: A comprehensive, multidisciplinary intervention delivered by a specialized team-including physical therapists and rehabilitation physicians-who collaboratively develop an individualized treatment plan tailored to each patient's functional deficits, baseline mobility, and specific spasticity profile. The physical therapy component emphasizes a combination of passive and active stretching protocols, therapeutic exercise to strengthen agonist muscles and improve motor control, gait and balance training, and adjunctive modalities such as neuromuscular electrical stimulation or therapeutic ultrasound, all administered at a frequency and intensity commensurate with the patient's tolerance and clinical progression. Concurrently, the multidisciplinary team addresses associated impairments through therapy focused on activities of daily living and limb function, pharmacological management with oral or antispastics injections as indicated

Study summary

Stroke is a non-progressive and permanent syndrome in adults, with approximately 60% of patients presenting with spastic hemiparesis. Spasticity leads to changes in the physiological pattern of muscle tissue contraction and hemodynamics, and, when left untreated, negatively impacts functionality. Photobiomodulation (PBM) has demonstrated positive effects on tissue regeneration, muscle relaxation, reduction of inflammation, fatigue, and pain relief in various muscular and neurological disorders. Methods: This blinded, randomized, controlled clinical trial aims to evaluate the effects of PBM on triceps surae muscle spasticity in adults with stroke. Forty-two participants with spastic hemiparesis post-stroke will be randomized into two groups: active PBM (850 nm, 200 mW, 4 J/point in the gastrocnemius, 12 points, weekly for 8 weeks) or placebo PBM (same protocol, device switched off). Both groups will receive the institute's standard rehabilitation treatment. Outcomes will be assessed using the Modified Ashworth Scale (MAS), ankle range of motion, presence of pain, amount of antispastic medication in use, contraction strength (by manual examination) muscle oxygenation (by transcutaneous near-infrared spectroscopy), functionality, and the occurrence of adverse events before and after the intervention. At the end of recruitment, comparisons between groups and between time points will be performed and statistically analyzed using a two-way repeated means ANOVA test and the Generalized Estimating Equations (GEE) test. We also foresee a pilot interim analysis when recruitment reaches a size of 10 participants per group. This interim analysis will be performed using a two-way/means ANOVA to assess effect size and recalculate sample size, making adjustments to the design if necessary.

Eligibility

Primary outcome measure(s)

• Spasticity Grade — Baseline" or "Day 1" and * through study completion, an average of 8 weeks. It will also be assessed immediately before and after each PBM session.
  The change in triceps surae spasticity severity, assessed using the Modified Ashworth Scale (MAS). The MAS is a widely validated, clinician-rated ordinal scale that quantifies muscle hypertonia by measuring the resistance encountered during passive joint mobilization; it grades spasticity from 0 (no increase in muscle tone) through 4 (affected part rigid in flexion or extension), with intermediate scores of 1, 1+, 2, and 3 denoting progressively greater degrees of resistance and catch phenomena throughout the range of motion.
• Spasticity Grade — Baseline" or "Day 1" and * through study completion, an average of 8 weeks.
  Quantity of antispastic medications used. Information regarding the medications (class, quantity, dose, and route of administration) used by participants for the treatment of spasticity before and after the end of the 8-week therapeutic period will be collected from medical records.

Trial sites (1)

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