Transcranial magnetic stimulation (TMS) has opened new potential avenues for the treatment of neuropsychiatric diseases via the effects of modulation on neuroplasticity. Repetitive TMS (rTMS) is a non-invasive method of stimulation neural pathways in the brain of conscious subjects through the intact scalp. The investigators hypothesize that excitatory rTMS applied over the motor cortex would increase motor cortex activity and result in an increase in the inhibitory input through the corticospinal tract to the spinal cord, thus reducing alpha neuron hyperactivity and consequently clinical spasticity. In this study, the investigators will apply the stimulation on the legs motor cortex area, which can cover supplemental motor area (SMA). Therefore, not only the spasticity, but also the motor control of legs both can be modulated by stimulation. Theta burst stimulation is a condition of rTMS which was designed by the co-investigator. It has controllable, consistent, long-lasting, and powerful effects on motor cortex physiology and behavior. The investigators therefore design this protocol using theta burst stimulation on the motor cortex of the patients of cerebral palsy. The investigators expect that there would be an effect on the reduction of spasticity after rTMS on the brain of children with CP, thus improving the motor control of legs.

In this study, the investigators design 3 steps to find out the optimal condition of rTMS for the treatment and managing of motor disability of CP. The first is to find out the optimal intensity of rTMS. The second is to find out the optimal duration of rTMS and long term effects. The third is to compare the effectiveness of botulinum toxin injection, rTMS, and combined therapy (botulinum toxin injection and rTMS) for children with CP.

Inclusion Criteria:

• diagnosis of mild to moderate CP with spastic diplegia or hemiplegia according to clinical criteria
• age 7-20 years
• no use of botulinum toxin in the past 4 months
• no significant perceptual or communication disturbances
• no other peripheral or central nervous system dysfunction
• no active inflammatory or pathologic changes in lower limb joints during the previous 6 months
• no active medical problems, such as pneumonia, upper gastrointestinal bleeding, or urinary tract infection
• no active problems of epilepsy and EEG without epileptiform discharge
• ability to walk 20m without walking aids, such as a cane, quadricane or walker

Exclusion Criteria:

• Metabolic disorders, such as inborn error of metabolism, electrolyte, and endocrine disorders.
• Active infectious disease, such as meningitis and encephalitis.
• Patients with active medical problems, such as pneumonia, upper gastrointestinal bleeding, or urinary tract infection.
• Poor compliance or intolerance for the TMS therapy
• Subjects with metallic implants or pregnancy.
• EEG show epileptiform discharge