Comparison of Two Botox Injection Techniques to Improve Gait

Universidad de los Andes, Chile18 enrolled

Overview

According to our hypothesis, the use of HD-EMG shall allow an accurate localization of the innervations zones of the muscles, offering a better complement to the methodology applied so far to define the botulinum neurotoxin (BoNT) injection site. To achieve that goal, a randomized clinical trial comparing the effectiveness of two guiding methods to define the BoNT injection site in the gastrocnemius muscles will be conducted. One arm will be guided with ultrasonography + localized IZ using anatomical references; while the second arm with ultrasonography + in vivo location of the IZ through HD-EMG. The effectiveness will be evaluated by changes in functional tests and in biomechanical parameters of the gait assessed with a three-dimensional motion analysis system. These outcomes will be measured at baseline (T0), at three (T3w) and six weeks (T6w), post BoNT injection. The differences between sessions will be evaluated as measurements of effectiveness. We expect that greater effectiveness will be found in the group that receives the injection of BoNT, guided by the in vivo location of the IZ.

This research proposal seeks to improve the current procedures to determinate the botulinum neurotoxin (BoNT) injection site. More precisely, we propose to complement the ultrasonography with an in vivo location of the IZ, using a non-invasive technique based on surface multielectrode electromyography grid, which is called high density-surface EMG (HD-EMG). According to our hypothesis, the use of HD-EMG shall allow an accurate localization of the IZs of the muscles, offering a better complement to the methodology applied so far to define the BoNT injection site. To achieve that goal, a randomized clinical trial comparing the effectiveness of two guiding methods to define the BoNT injection site in the gastrocnemius muscles (main ankle extensors or plantar flexors) will be conducted. One arm will be treated with the best available option, which includes ultrasonography + localized IZ using anatomical references. The second arm will be managed using ultrasonography + in vivo location of the IZ through. The last will be measured using HD-EMG by recording the motor unit action potentials along the muscle fibers. This technique can identify the location of the IZ by the change of phase of those potentials. The effectiveness will be evaluated by changes in biomechanical parameters of the gait, assessed using a three-dimensional motion analysis system. The outcomes will be biomechanical gait variables associated with the ankle joint (ankle joint moment, dorsiflexion range, among others) and functional tests (spasticity using Ashworth scale, 6-minute walk test and the Timed Up and Go Test). These outcomes will be evaluated at baseline (T0), at three (T3w) and six weeks (T6w), post BoNT injection. The differences between sessions will be evaluated as measurements of effectiveness (Delta1 = T3w-T0; Delta2 = T6w - T0). To compare the effectiveness between groups, these delta values will be compared using a student's t-test or a Mann-Whitney U test, as appropriate. Also, a Cohen's d will be calculated to determine the magnitude of these differences. In addition, the post-hoc power (1-β) will be measured. All statistical analyses will be performed in the STATA software (version 14.0 Stata-Corp LP, USA), considering a one tailed analysis, and a confidence level of 95%. Statistically significant differences will be considered those associated with a p-value lower than 0.05. We expect to find greater effectiveness in the group that receives the injection of BoNT, guided by the in vivo location of the IZ using HD-EMG.

Interventions

Botulinum toxin guided by ultrasonography and anatomical referencesCOMBINATION_PRODUCT

The botulinum neurotoxin (BoNT) will be calculated according to the weight of each patient. It will be injected in four places: two of them into the medial gastrocnemius and the other two into the lateral gastrocnemius. For medial gastrocnemius muscle, ¼ of the dose will be injected into the muscle belly at the 25% of the distance between the popliteal fossa and the intermalleolar line. Another ¼ will be injected into the muscle belly at the 35% of the previously mentioned distance. For lateral gastrocnemius, ¼ of the dose will be injected into the muscle belly at the 20% of the distance between the popliteal fossa and the intermalleolar line. The remaining ¼ of the dose will be injected into the muscle belly at the 30% of the previously described distance. All patients will conduct the same physical therapy program and under the direction of the same team of physical therapists. This program will begin two weeks after receiving the BoNT injection.

Botulinum neurotoxin guided by ultrasonography and in vivo location of innervation zones guided by high-density electromyographyCOMBINATION_PRODUCT

The botulinum neurotoxin (BoNT) will be calculated according to the weight of each patient. It will be injected in eight places: four will be located in vivo for gastrocnemius medialis and four for gastrocnemius lateralis. These places will correspond to innervation zones located by high-density electromyography in different zones of each muscle. Thus, each of the eight located innervation zones will receive 1/8 of the calculated dose for the gastrocnemius muscle. All patients will conduct the same physical therapy program and under the direction of the same team of physical therapists. This program will begin two weeks after receiving the BoNT injection.

Outcomes

Primary Outcomes

Maximum ankle dorsiflexion during the stance phase in the paretic limb.

Peak dorsiflexion angle during the stance phase in the paretic limb. This value will be calculated from Vicon Nexus 2.12 software, using the conventional gait model + functional calibration, and will be considered as the average value within 8 to 10 gait cycles.

Time frame: Before intervention (T0), three weeks (T3w) and six weeks (T6w) post botulinum neurotoxin injection

Maximum ankle plantarflexion moment during the stance phase in the paretic limb

Peak internal ankle dorsiflexion moment during the stance phase in the paretic limb. This value will be calculated from Vicon Nexus 2.12 software, using the conventional gait model + functional calibration, and will be considered as the average value within 8 to 10 gait cycles.