Correlation between current intensity and effective duration in the treatment of botulinus toxin for cerebral palsy by myoelectricity locating

摘要

BACKGROUND: Researches prove that the treatment of cerebral palsy by botulinus toxin (BTX-A) can improve effect and prolong effective duration. Current intensity is the important factor during injection.OBJECTIVE: To observe the changes of motor function and muscular intensity of children with spastic cerebral palsy after injecting BTX-A and analyze correlation between current intensity and effective duration. DESIGN: Cases control trial before and after nerves block.SETTING: Capital University of Medical Sciences, China Rehabilitation Research Center.PARTICIPANTS: From June 2002 to November 2004, 14 children with spastic cerebral palsy were treated by BTX-A block. All children were hospitalized in the Children Rehabilitation Department of China Rehabilitation Research Center. The children included 9 male and 5 female, and ranged from 4 to 13 years old, and average age was (6±2) years. Muscular tension ranged from grade 1 to grade 3. The diagnosis and the tape of cerebral palsy based on standard of the Fist Nationwide Cerebral Palsy Symposium, and all children were diagnosed with electroencephalogram (EEG), CT and MRI, and permitted by their guardians.METHODS: ① Locating and calculation: To locate block points by G6805-2A electro-therapeutic apparatus (Shanghai Huayi Electronic Instrument Plant) at the least stimulating current (continuous wave; impulse frequency; 2.667-83.333 Hz; current intensity: 0-6 mA; voltage: 6 V) to touch off muscles contraction. The current intensity of each point was recorded, and the average current intensity of each patient was calculated at the same time. ② Dose of BTX-A: Basing upon the spastic degree and weight of patients, the dose was made certain: dose (IU)=(scores of Modified Ashworth Scale +2.5) ×weight (kg). The number of the block points was in all 4. The dose of injection ranged from 50 IU to 160 IU with the average of (73.6±25.8) IU. The BTX-A was made by Lanzhou Institute of Biological Products, and each bottle contains 100 IU BTX-A. Muscular tension was evaluated by Modified Ashworth Scale. The scale ranged from grade 0 to grade 4, and the scores were from 0 to 4. The higher the scores were, the higher the muscular tension was. ③ Effect: Changes of muscular tension were evaluated by modified Ashworth Scale before and after block. Motor function was evaluated by Physician Rating Scale (PRS) before and after treatment. It contained Gait pattern, Hindfoot (ankle) position (stance-floor contact), Hindfoot position (foot strike), Knee position (degree of recurvation), Crouch and Speed of gait. The scores ranged from 0 to 14. The higher the points were, the better the motor function was. ④ Effective duration: The duration was definited by the recovering of the Modified Ashworth Scale. ⑤ Statistic analysis: Firstly, the current intensity and the effect duration were analyzed by One-Sample Kolmogorov-Smirnov Test, the current intensity: Z = 0.456, P = 0.985, the effective duration: Z = 0.557, P = 0.915. Both data were normal distribution. Secondly, both data were analyzed by Linear Regression. The efficiency of the BTX-A block was analyzed by paired-samples t test.MAIN OUTCOME MEASURES: ① Changes of motor function of muscular tension; ② correlation between current intensity and effective duration. RESULTS: Fourteen children with spastic cerebral palsy were all involved in the final analysis. ① Therapeutic effect: The average score of Ashworth scale after block was lower than that before block [(1.02±0.34) points vs. (2.12±0.48) points, t = 3.644, P < 0.01]. The average score of RPS after block was higher than that before block [(9.75±2.78) points vs. (6.16±0.58) points, t =13.222, P < 0.01]. ② Relation between the current intensity and the effective duration: The current intensity was (0.1857±0.0506) mA, and the effective duration was (26.36±4.48) weeks. The current intensity was negative correlation with effective duration (r = -0.775, P = 0.01).CONCLUSION: ① BTX-A occlusion can decrease muscular tension and improve motor function of lower limbs of children with spastic cerebral palsy. ② The lower the current intensity is, the longer the effective duration is.