Spasticity Reduction Does Not Lower CP Children’s Energy Consumption While Walking, Study Finds

Selective dorsal rhizotomy, a surgery that lessens spasticity (muscle stiffness) in children with cerebral palsy, does not reduce their energy consumption during walking, a retrospective study has found.

The study, “Spasticity reduction in children with cerebral palsy is not associated with reduced energy consumption during walking,” was published in the preprint server BioRxiv.

Children with cerebral palsy (CP) expend, on average, over two times the energy to walk than typically developing children. As a result, fatigue is a top complaint of these children and reported by their families.

Spasticity, or muscle stiffness, has been proposed as the root cause for this extra energy consumption, but this link remains to be established.

Spasticity can cause an increase in overall muscle activity and is observed in up to 80% of children with cerebral palsy.

To better understand whether spasticity can be a significant contributor to the observed increase in energy consumption during walking, researchers at the University of Washington and University of Minnesota, Twin Cities, investigated if reducing spasticity could lower energy consumption in children with cerebral palsy.

The team retrospectively compared the energy spent in walking by 242 children with diplegic CP — a form of the disease marked by spasticity — before and after they had selective dorsal rhizotomy (SDR). SDR is a neurosurgical procedure involving the sectioning of some sensory nerve fibers that come from the muscles and enter the spinal cord. The surgery has been shown to reduce spasticity significantly.

The study used retrospective data from clinical gait analysis of children seen at Gillette Children’s Specialty Healthcare between 1994 and 2018. All participants underwent a bilateral SDR before the age of 12.

A control group, matched by age, spasticity, and energy consumption, was used consisting of 156 patients who did not undergo SDR.

Limb spasticity scores and energy consumption during walking were compared at baseline (study start) and follow-up visits for both groups.

As expected, the SDR group had a greater reduction in spasticity (of 44%) during follow-up compared with control subjects who did not undergo surgery (16%).

“While both groups had a reduction in energy consumption between visits (12% SDR and 14% no-SDR), there was no difference in the change in energy consumption between groups,” the researchers wrote.

Therefore, SDR did not result in a greater reduction in energy consumption. This suggests that “spasticity is not a primary factor contributing to the increased walking energy in children with CP” and that alleviating this problem with surgery “does not contribute to greater reductions in energy consumption,” the researchers said.

These findings also agree with the idea that energy consumption decreases with age among children with CP, regardless of treatment.

“To our knowledge, no studies have included a control group of peers with CP when looking at the impact of SDR on energy consumption,” the researchers wrote.

“Selecting appropriate control groups is critical for research involving children with CP to account for changes in function due to age, development, and other factors. While SDR is often suggested to reduce spasticity and improve energy, clinicians and families should understand that this procedure does not improve energy consumption during walking,” they concluded.