Short Term Follow-up of a Botulinum Toxin Intervention in Children With Spastic Cerebral Palsy

Aim:

This study investigates the effect of integrated Botulinum Neurotoxin A (BoNT) treatment on morphologic muscle and tendon properties (muscle length and muscle volume, assessed with a 3D ultrasound measurement), spasticity and joint stiffness (measured with an instrumented spasticity assessment), joint range of motion (measured through goniometry), muscle strength (measured using dynamometry), gait (assessed through 3D gait analysis) and gross motor function (assessed using clinical test batteries). The aim is twofold: (1) determine whether integrated BoNT treatment of the medial gastrocnemius and the semitendinosus muscle(s) leads to changes in the morphologic muscle and tendon properties of the medial gastrocnemius and the semitendinosus muscle(s), the ankle and knee range of motion, spasticity, stiffness, muscle strength and gait, and (2) determine the correlation between baseline morphologic muscle and tendon properties and the changes in the primary outcome parameters (spasticity and stiffness) following the BoNT-treatment.

Design:

The current study has a non-randomized controlled design. Because BoNT is proven an effective treatment to reduce spasticity and improve gross motor function, it cannot be clinically justified to allocate children to a non-treatment group, if a new BoNT treatment is required. Delayed BoNT treatment could rapidly increase musculoskeletal impairments. It is therefore considered unethical to temporarily withdraw BoNT treatment from patients. To compensate the lack of randomization accurate matching of groups is required. Children will be matched on diagnosis (uni/bilateral CP), GMFCS level, age and spasticity level.

BoNT-treatment:

All children in the intervention group will receive BoNT injections in the medial gastrocnemius and/or the semitendinosus muscle(s) (other muscles may also be treated as part of multilevel treatment). As part of the standard integrated treatment approach of the CP Reference Centre of the University Hospitals Leuven, the injections are followed by a period of bilateral stretching casts if indicated (below the knee walking casts and removable knee extension casts when necessary) and all children will receive intensive physical therapy and application of orthotic management following BoNT injections. The follow-up period for the current study is 8-10 weeks. During this intensive physical therapy post-BoNT, the children in the intervention group will work on individualized treatment goals. These goals will be defined based on the baseline measurements during a multidisciplinary discussion with the treating physician, which is scheduled prior to the BoNT treatment. The fulfillment of these patient-specific goals will be evaluated by the Goal Attainment Score (GAS). During the follow-up period, the treating physical therapist will be interviewed on a two-weekly basis to verify whether and to what extend the therapy is focused on the personal treatment goals. Assessments of morphologic muscle and tendon properties, spasticity, stiffness, joint range of motion, muscle strength, and gait of the participants will be performed before the BoNT injections, and 8-10 weeks after the injection. This period of 8-10 weeks follow-up post BoNT injections was found to be appropriate, since the potential effect of BoNT on gross motor function is expected to be optimal after 6-10 weeks.

Study groups:

The study will include patients who are diagnosed with spastic CP, aged between 4 and 11 years and with Gross Motor Function Classification System (GMFCS) level I-III. The intervention and control group will be group-matched based on diagnosis (uni/lateral CP), GMFCS level, age and spasticity level.

Overall exclusion criteria were: BoNT injections less than 6 months before inclusion, a treatment history that includes previous selective dorsal rhizotomy treatment or a bony surgery less than 2 years before inclusion, and limited cooperation that would prevent a proper assessment. For all enrolled children, intensive rehabilitation post BoNT injections had to be foreseen as the standard care. For the intervention group, 30 children with a clinical indication for BoNT injections in the medial gastrocnemius and/or semitendinosus muscle(s) will be recruited, while for the control group, 30 children without an indication for a specific intervention in the next 3 months will be recruited.

For the intervention group, the baseline measures will be followed by the BoNT injections combined with casting and goal-oriented physical therapy (as described above), and the follow-up assessments will be planned 8-10 weeks post BoNT injections. Baseline and follow-up assessments for the intervention groups include 3D ultrasound, the instrumented spasticity measurement, functional strength tests, and 3D gait analysis.

The children in the control group will also be assessed twice with an interval of 8-10 weeks. During the 8-10 weeks, they will continue their usual care or normal routine treatment, i.e. regular physiotherapy and orthotic devices. Baseline and follow-up assessments for the control group include 3D ultrasound, the instrumented spasticity measurement and functional strength tests.

Inclusion criteria

• Confirmed diagnosis of spastic cerebral palsy
• Aged 4-11 years
• GMFCS levels I-III (GMFCS = Gross Motor Function Classification Score, expressing the overall functional level of impairment)
• Sufficient cooperation to comprehend and complete the test procedure
• Additional exclusion criterion for the intervention group specifically: Indication for BoNT injections

Exclusion criteria

• Non-ambulatory
• Botulinum toxin A injections six months prior to enrollment
• Lower limb surgery two years prior to enrollment
• Previous selective dorsal rhizotomy
• Presence of ataxia or dystonia
• Cognitive problems that impede measurements
• Severe co-morbidities (severe epilepsy, non-correctable visual impairment, autism spectrum disorders, mental problems that prevent comprehensiveness of the tasks)
• Hospitalization after the BoNT treatment for intensive physical therapy
• Intrathecal baclofen pump
• For the control group: new intervention planned within 3 months
• Additional exclusion criterion for the control group specifically: new intervention planned within 3 months