Gross Motor Function Measure Article Summary
Purpose: The purpose of the study was to assess gait changes over time after children diagnosed with cerebral palsy received a botulinum toxin type A (BTX-A) injection.
Study population: The study included nine children between the ages of 4 and 8 years old diagnosed with wither hemiplegic or diplegic cerebral palsy, of which the gross motor functional classification system (GMFCS) was used to assess the severity. Each participant had previously received BTX-A treatment 2-15 times, one of which had been in the last 3-6 months.
Methods and Intervention: BTX-A injections were placed in the following muscles, different per participant: hip adductor muscle, rectus femoris, hamstrings, gastrocs, soleus, tibialis posterior and upper limb muscles. Measurements were taken before the injection, and at 4-weeks, 8-weeks and 12 weeks post-injection.
Outcome measures: The participants were brought in to have measurements performed four times throughout the study: before BTX-A injection, 4 weeks post-injection, 8 weeks post-injection, 12 weeks post injection. The following measures were taken:
- ROM: passive at slow speed (hip abduction, popliteal angle, ankle dorsiflexion with 90 degrees of knee flexion – DKF, ankle dorsiflexion with knee extension – DKE)
- MTS: angle where “catch” happened with fast passive movement (hip abduction, popliteal angle, ankle dorsiflexion with 90 degrees of knee flexion – DKF, ankle dorsiflexion with knee extension – DKE)
- Isometric maximum knee joint extension torque: handheld dynamometer in standardized positions
- Gross Motor Function Measure-66 (GMFM-66): outcome measure to evaluate gross motor function differences, especially in those diagnosed with cerebral palsy; 66 question version instead of GMFM-88 which has 88 questions. Both version address categories including lying and rolling, sitting, crawling and kneeling, standing, and walking/running/jumping using a 4-point Likert scale
- Gait analysis: digital cameras and markers were used to observe gait in the sagittal plane while measuring gait speed, step length, hip/knee/ankle joint angle during gait, Foot Contact Scale (FCS), Physician’s Rating Scale (PRS)
Results:
- ROM: DKE was the only joint angle that showed significant increase after 8 weeks. However, improvements were also shown in the popliteal angle after 8 weeks and after 4 weeks in the hip abduction and DKF.
- MTS: While no changes were significant, after 4 weeks hip abduction, popliteal angle and DKF showed improvement along with DKE after 8 weeks.
- Knee extension torque: Results showed a significant increase during three time periods throughout the study; initial testing to post-injection 12 weeks, 4 weeks post-injection to 12 weeks out, and from 8 weeks post-injection to 12 weeks after (p<0.05)
- GMFM-66: Only from initial testing to post-injection week 8 did the researchers find a significant difference.
- Gait function: Improvements in FCS and PRS were shown from initial testing to post-injection week 4 as well as gait speed and step length after 12 weeks. However, the only significant differences were observed in initial contact angle and maximum angle of dorsiflexion from initial testing to post-injection week 8.
Strengths: The researcher looks at how BTX-A injections affect children with CP at different time periods, showing what changes happen and when. This can be helpful for physical therapy treatment to know when specific therapeutic measures should be expected to improve and how to optimize treatment plans.
Limitations: One of the major limitations to the study includes the inconsistent injection sites per participant. Along with location of injection, each of the participants had previously received different numbers of treatments, which may play a role on how the bodies react to the medication. Another limitation is the length of the study. Previous research shows that patients can continue to demonstrate improved strength after 12 weeks post-injection. Further testing could have been performed to see an optimal strength improvement if it happened after the study was completed. A larger sample size with more diverse array of the severity of the children’s CP would also help build power of the study.
Conclusion: The research showed that after BTX-A injections, the most improvements in gait happen around the 8-week time period for the nine children diagnosed with CP between the ages of 4 and 8. Significant improvements were observed in multiple different measurements including maximum dorsiflexion angle during the gait cycle, ankle dorsiflexion passive ROM, and GMFM-66 8 weeks after the injection as well as lower extremity strength at the 12 week mark.
Reference: Matsuda M, Tomita K, Yozu A, et al. Effect of botulinum toxin type A treatment in children with cerebral palsy: Sequential physical changes for 3 months after the injection. Brain and Development. 2018;40(6):452-457. doi:10.1016/j.braindev.2018.02.003
2 responses to “Gross Motor Function Measure Article Summary”
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Great review, Dani!
I also find it interesting that they did not extend the trial beyond 12 weeks. It would be interesting to see when improvements started to decline, as well as what the rate of decline was. Do you know if they were receiving any type of therapy during this time?
Thanks,
Haley
Thank you for your question Haley. The article did not specify what rehab measures were being taken during the study. However, it did address in the conclusion that therapy after the injection is required for a longer duration over multiple months as short-term therapy post-injection may not yield the same outcomes.