Cerebral palsy is a non-progressive, permanent syndrome that occurs in childhood and is accompanied by motor, tônus and posture disorders. Its etiology is related to an insult or damage to the central nervous system in maturation. Approximately 80% of cerebral palsy course with spasticity, which, when left untreated, will generate pain and functional, anatomical and structural changes, with a negative impact. Photobiomodulation therapy has biological effects of tissue regeneration, muscle relaxation, vasodilation, reduction of the inflammatory process and relief of pain symptoms already described in the literature, in addition to being feasible, practical, safe, without side effects, painless and non-invasive.This study is a blind, randomized and controlled clinical trial that will evaluate the effect of photobiomodulation in reducing gastrocnemius muscle spasticity in children aged 2 to 18 years, diagnosed with spastic cerebral palsy of lower limbs of any etiology for at least 03 months and randomized into two groups: application of Low Intensity LED Therapy in the medial and right lateral gastrocnemius muscles (device power of 100mW, wavelength of 850nm, energy of 3J/cm2/point, once a week, making 08 therapeutic days during 02 months) or placebo group Low-Intensity LED Therapy (same device turned off). Both groups will also receive the standard treatment for spasticity. To assess the response to therapy, the outcomes evaluated will be the modified Ashworth Scale, the Mobility Domain of Pediatric evaluation of disability inventory, the Gross Motor Function Classification System scale and passive and active range of motion of the ankle analyzed at the pré and post each therapeutic session and in the pre and post therapeutic period of 08 sessions.

Cerebral palsy is a non-progressive, permanent syndrome that occurs in childhood and is accompanied by motor, tonus and posture disorders. Its etiology is related to an insult or damage to the central nervous system in maturation, during the prenatal, perinatal or postnatal period, when the central nervous system has not yet fully developed.

Approximately 80% of cerebral palsy course with spasticity, which, when left untreated, will generate pain and functional, anatomical and structural changes in bones, joints, muscles, tendons and nerve junctions, with a negative impact on quality of life, social participation and functionality of this individual. In parallel, photobiomodulation therapy has biological effects of tissue regeneration, muscle relaxation, vasodilation, reduction of the inflammatory process and relief of pain symptoms already described in the literature, in addition to being feasible, practical, safe, without side effects, painless and non-invasive.Objectives and methods: this study is a pilot, double-blind, randomized and controlled clinical trial that will evaluate the effect of photobiomodulation in reducing gastrocnemius muscle spasticity in 28 children aged 2 to 18 years, diagnosed with spastic cerebral palsy of right lower limb of any etiology for at least 03 months, selected at the

Physiotherapy Service of Universidade Nove de Julho and randomized into two groups:

application of Low Intensity LED Therapy in the medial and right lateral gastrocnemius muscles (device power of 100mW, wavelength of 850nm, energy of 1.5 J/point, applied in 02 points per muscle, for 15 seconds, frequency of once a week, making 8 therapeutic days) or placebo group Low-Intensity LED Therapy (same device turned off). Patients with fixed anatomical deformity of the ankle with less than 90 degrees of dorsiflexion amplitude, malnutrition, severe gastroesophageal reflux disease and another type of associated movement disorder will be excluded. Both groups will also receive the standard treatment for spasticity performed by the hospital's rehabilitation health team.

To assess the response to therapy, the outcomes evaluated will be the modified Ashworth Scale (MAS), the Mobility Domain of Pediatric Evaluation of Disability Inventory for children (PEDI), the Gross Motor Function Classification System scale (GMFCS) and passive range of motion (ROM) of the ankle analyzed at the end of each therapeutic session and in the pre therapeutic period of 08 weeeks. Epidemiological data will be collected from the medical records of participants in the physiotherapy for characterizing the sample (age, gender,etiology of brain injury and type of paralysis, injury time, medications, comorbidities, previous surgeries, length of physiotherapy treatment at the start of the study, description of the physiotherapy treatment in use, use of a walking aid or orthosis. Data will be statistically analyzed and positive or negative results reported and discussed.

Inclusion Criteria:

• Patients with diagnosis of spastic cerebral palsy affecting inferior limbs from any etiology;
• Cerebral palsy duration at least 03 months;
• Patients ongoing physiotherapy treatment at University.

Exclusion Criteria:

• Patients with fixed anatomical deformities of the ankle that do not allow ankle joint movement of at least 90 degrees of amplitude;
• Patients with malnutrition;
• Patients who present acute clinical conditions with potential for increase spasticity such as acute fractures, skin ulcers, acute infections;
• Patients with severe gastroesophageal reflux disease;
• Patients with another type of movement or tone disorder;
• Patients who have exposed tumors in the area to be irradiated;
• Patients with a history of photosensitivity to photonic or light therapy;
• Patients who have undiagnosed lesions in the treatment region;
• Patients using topical photosensitizing medications or creams;

The data will be share with Mendeley Data database or similar