Abstract: Objective To determine the coefficient in the formula of the optimal dose of botulinum toxin A(BTX-A) to treat spastic cerebral palsy(CP).Methods58 CP children(male 38,female 20,mean age 59.3±24.6 months,range 27 to 144 months) were divided into A,B,C,D and E five groups according to used coefficient and treated by BTX-A with different doses to release the spasticity.ResultsAccording to the improvement of motor function,the BTX-A dose of the group D was optimal.According to the effective endurance,the BTX-A dose of the group C was optimal.The optimal coefficient was 1.8.ConclusionThe formula of the optimal BTX-A dose injected in triceps surae is dose =(1+1.8×MAS score)×body weight.

Key words: cerebral palsy, spasm, botulinum toxin A(BTX-A), nerve block, dose