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

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.

Inclusion criteria

• Adults who have sustained a unilateral ischemic or hemorrhagic cortical motor stroke, with the diagnosis documented in the acute phase by computed tomography (CT) or magnetic resonance imaging (MRI);
• Patients currently undergoing multidisciplinary rehabilitation at the Rehabilitation Center where the study will be conducted;
• Patients presenting with a motor pattern of spastic hemiparesis secondary to stroke;
• Patients demonstrating the ability to perform orthostatism (standing posture) or therapeutic or functional gait activity.

Exclusion criteria

• Presence of uncontrolled systemic diseases, including but not limited to cancer, active infections, or uncontrolled diabetes mellitus;
• History of photosensitivity or known hypersensitivity to light exposure;
• Triceps surae spasticity graded as 4 on the Modified Ashworth Scale (MAS) at the initial pre-screening assessment;Acute clinical instability or any acute medical condition requiring immediate intervention;
• Fixed anatomical deformities of the ankle joint that preclude a minimum passive or active range of motion of at least 60 degrees;
• Malnutrition or significant nutritional deficiencies;Acute clinical conditions with the potential to exacerbate spasticity, such as acute fractures, cutaneous ulcers, or acute infections;Presence of any other movement or tone disorder (e.g., dystonia, chorea, or parkinsonism) that could confound spasticity assessments;
• Exposed tumors or undiagnosed lesions in the area to be irradiated;
• Change in the pharmacological class of antispastic medications during the therapeutic period of the study. Dose adjustments within the same medication class will be permitted and documented;
• Administration of botulinum toxin type A injections into the triceps surae muscle during the study period or within six months prior to study enrollment;
• Discontinuation of the concomitant physical therapy rehabilitation program, even if the participant continues to receive photobiomodulation per the study protocol;
• Occurrence of any adverse event attributable to photobiomodulation;
• Death;
• Withdrawal of informed consent.