Background :Spasticity is a motor disorder in children with cerebral palsy (CP) Cp is a non progress lesion in unmature brain lead to a group of chronic disorders that affect movement and posture development, may be accompanied by epilepsy, secondary musculoskeletal problems, deformaties and disturbances of sensation, perception, cognition, communication, and behavior Few studies demonstrate effectiveness of laser therapies in spasticity in cp.

Methodology : This study is randomize control trail aimes to evaluate the effect of low-level laser therapy (LLLT) on the spasticity of hamstring and calf muscle in children with CP over 12 session of intermittent laser exposures. Muscle tone , gross motor function, rang of motion (rom ) and poplital angle will evaluate before and after laser irradiation in 30 children with CP both geneder aged between two to six years old diaplegic clidren , exclusion children who take botox or done surgery . Muscles will irradiated with low-intensity diode laser pulses of 808-nm wavelength three times per week over one month follow up for one month.

This is a randomized controlled study, in which the 30 children with diaplegic randomly divide into control and study groups by excel sheat on computer, each group include 15child. Each child will receive laser at a frequency of three sessions per week for 12 session, in addition to conventional physiotherapy program, while the control group have 15 child will receive conventional physiotherapy. Four variables will choose to detect the effect of laser therapy: (1) muscle tone, (2) range of motion (ROM) , (3) gross movement,(4) poplital angle assessment . These values will recorde in both groups before starting treatment and after the treatment period and after one month of stop treatment .

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Inclusion Criteria:

• spastic diaplegic children aged between 2 to 6years have spastic hamstring and calf muscle .

Exclusion Criteria:

• for post-operative children , children who take botox, children with contracture or fixed deformity