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Spasticity and strength changes as a function of selective dorsal rhizotomy
J R Engsberg1, K S Olree, S A Ross
1Human Performance Laboratory, Barnes-Jewish and St. Louis Children's Hospitals, St. Louis, Missouri; and Department of Neurosurgery, Washington University School of Medicine, St. Louis, Missouri.
Insights
Selective dorsal rhizotomy reduced hamstring spasticity in children with cerebral palsy (CP). Post-surgery, hamstring strength increased significantly in the CP group compared to pre-surgery levels.
Area of Science:
- Orthopedics
- Neurology
- Pediatrics
Background:
- Cerebral palsy (CP) often involves hamstring spasticity and weakness.
- Selective dorsal rhizotomy (SDR) is a surgical intervention for managing spasticity in CP.
Purpose of the Study:
- To quantify changes in hamstring muscle spasticity and strength in children with CP after SDR.
- To compare post-SDR outcomes with pre-SDR measurements and a control group.
Main Methods:
- Nineteen children with CP and six able-bodied children were assessed using a dynamometer.
- Spasticity was measured by hamstring muscle resistive torque during passive knee extension at varying speeds.
- Strength was assessed by measuring the work done during maximal hamstring muscle contraction.
Main Results:
- Pre-surgery, children with CP exhibited significantly greater hamstring spasticity than the able-bodied group.
- Post-surgery, hamstring spasticity in the CP group was no longer significantly different from the able-bodied group.
- Hamstring strength in the CP group remained lower than the able-bodied group but showed a significant increase from pre-surgery levels.
Conclusions:
- Selective dorsal rhizotomy effectively reduces hamstring spasticity in children with CP.
- SDR leads to significant improvements in hamstring strength in children with CP, contrary to some previous findings.
Abstract:
This investigation quantified pre- and postsurgery (8 months) hamstring muscle spasticity and strength in children with cerebral palsy (CP) undergoing a selective dorsal rhizotomy. Nineteen children with CP (CP group) and six children with able bodies (AB group) underwent testing with a dynamometer. For the spasticity measure, the dynamometer measured the resistive torque of the hamstring muscles during passive knee extension at four different speeds. Torque angle data were processed to calculate the work done by the machine to extend the knee for each speed. Linear regression was used to calculate the slope of the line of best fit for the work velocity data. The slope simultaneously encompassed three key elements associated with spasticity (velocity, resistance, and stretch) and was considered the measure of spasticity. For the strength test, the dynamometer moved the leg from full knee extension to flexion while a maximum concentric contraction of the hamstring muscles was performed. Torque angle data were processed to calculate the work done on the machine by the child. Hamstring spasticity values for the CP group were significantly greater than similar values for AB group prior to surgery; however they were not significantly different after surgery. Hamstring strength values for the CP group remained significantly less than those for the AB group after surgery, but were significantly increased relative to their presurgery values. The results of spasticity testing in the present investigation agreed with previous studies indicating a reduction in spasticity for the CP group. The results of strength testing did not agree with those in the previous literature; a significant increase in strength was observed for the CP group.
