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Quantitative clinical measure of spasticity in children with cerebral palsy
J R Engsberg1, K S Olree, S A Ross
1Department of Neurosurgery, St. Louis Children's Hospital, MO 63110, USA.
Insights
A new objective measure quantifies spasticity using a single variable integrating velocity, range of motion, and resistance. This method effectively differentiates spasticity in children with cerebral palsy from able-bodied children.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Pediatric Rehabilitation
Background:
- Spasticity is a common motor disorder affecting children with cerebral palsy.
- Quantifying spasticity objectively is crucial for diagnosis and treatment monitoring.
- Existing measures may not fully capture the dynamic nature of spasticity.
Purpose of the Study:
- To develop and validate an objective, single-variable measure for quantifying spasticity.
- To integrate key spasticity characteristics: velocity, range of motion, and resistance.
- To differentiate spasticity levels between children with cerebral palsy and able-bodied children.
Main Methods:
- A prospective descriptive study utilizing a dynamometer to measure hamstring resistance during knee extension.
- Data collected at four different speeds across a range of motion.
- Calculated the slope of work-velocity curves from torque-angle data.
Main Results:
- Able-bodied children showed minimal change in passive resistance with increasing speed (slope ≈ 0.003 J/(degrees/sec)).
- Children with spastic diplegic cerebral palsy exhibited significantly greater resistive torques at higher speeds.
- The calculated slope for children with cerebral palsy was approximately 10 times higher (0.031 J/(degrees/sec)) and statistically significant (p < .05).
Conclusions:
- The slope of the work-velocity curve provides a robust, single-number measure of spasticity.
- This objective measure integrates critical spasticity components (velocity, range of motion, resistance).
- The method is clinically interpretable and uses readily available equipment.
Objective:
This investigation developed an objective measure to quantify the degree of spasticity.
Design:
Specifications included a single variable that integrated key elements characterizing spasticity: velocity, range of motion, and resistance to passive motion. A dynamometer at a children's hospital quantified the passive resistance of the hamstrings to knee extension for a range of motion at 4 different speeds for the prospective descriptive investigation.
Patients:
A convenience sample of six children with able bodies and 17 children with spastic diplegic cerebral palsy volunteered. DATA PROCESSING: Torque-angle data were processed to calculate the work done by the machine on the children for each speed and then determine the slope of the work-velocity curves. This slope was considered to be the measure of spasticity and it was hypothesized that children with cerebral palsy would have a greater slope than children with able bodies. An independent test determined whether a significant difference existed between groups (p < .05).
Results:
Torque-angle data for children with able bodies indicated little change in passive resistance as a function of speed. Similar data for children with cerebral palsy indicated larger resistive torques with increasing speed. Slope from the work-velocity data was close to zero for children with able bodies [.003 J/(degrees/sec)], while the corresponding slope for children with cerebral palsy was approximately 10 times greater [.031 J/(degrees/sec)] and significantly different (p < .05).
Conclusion:
The slope of the work-velocity data integrates three major components characterizing spasticity, it is a single number that can easily be evaluated and interpreted in a clinical setting, and it utilizes a machine that is available at many centers.