Predictors for the benefit of selective dorsal rhizotomy.

Selective dorsal rhizotomy (SDR) is a spasticity reducing treatment option for children with spastic cerebral palsy. Selection criteria for this procedure are inconclusive to date. Clinical relevance of the achieved functional improvements and side effects like the negative impact on muscle strength are discussed controversially. In this prospective cohort study one and two year results of 54 children with a mean age of 6.9 (±2.9) years at the time of SDR are analyzed with regard to gross motor function and factors affecting the functional benefit. Only ambulatory children who were able to perform a gross motor function measure test (GMFM-88) were included in this study. Additionally, the modified Ashworth scale (MAS), a manual muscle strength test (MFT), and the body mass index (BMI) were evaluated as possible outcome predictors. MAS of hip adductors and hamstrings decreased significantly (p<0.001) and stayed reduced after two years, while GMFM improved significantly from 79% to 84% 12 months after SDR (p<0.001) and another 2% between 12 and 24 months (p=0.002). Muscle strength did improve significantly concerning knee extension (p=0.008) and ankle dorsiflexion (p=0.006). The improvement of function correlated moderately with age at surgery and preoperative GMFM and weakly with the standard deviation score of the BMI, the dorsiflexor and plantarflexor strength preoperatively as well as with the reduction of spasticity of the hamstrings and the preoperative spasticity of the adductors and hamstrings. Correctly indicated SDR reduces spasticity and increases motor skills sustainably in children with spastic cerebral palsy corresponding to clinically relevant changes of GMFM without compromising muscular strength. Outcome correlates to GMFM and age rather than to MAS and maximal strength testing. The data of this evaluation suggest that children who benefit the most from SDR are between 4 and 7 years old and have a preoperative GMFM between 65% and 85%.

Temporal but not spatial variability during gait is reduced after selective dorsal rhizotomy in children with cerebral palsy.

INTRODUCTION: Variability in task output is a ubiquitous characteristic that results from non-continuous motor neuron firing during muscular force generation. However, variability can also be attributed to errors in control and coordination of the motor neurons themselves in diseases such as cerebral palsy (CP). Selective dorsal rhizotomy (SDR), a neurosurgical approach to sever sensory nerve roots, is thought to decrease redundant or excessive afferent signalling to intramedullary neurons. In addition to its demonstrated ability to reduce muscular spasticity, we hypothesised that SDR is able to decrease variability during gait, the most frequent functional motor activity of daily living. METHODS: Twelve CP children (aged 6.1 ± 1.3 yrs), who underwent SDR and performed gait analysis pre- and 12 months postoperatively, were compared to a control group of eleven typically developing (TD) children. Coefficients of variability as well as mean values were analysed for: temporal variables of gait, spatial parameters and velocity. RESULTS: Gait parameters of cadence (p = 0.006) and foot progression angle at mid-stance (p = 0.041) changed significantly from pre- to post-SDR. The variability of every temporal parameter was significantly reduced after SDR (p = 0.003-0.049), while it remained generally unchanged for the spatial parameters. Only a small change in gait velocity was observed, but variability in cadence was significantly reduced after SDR (p = 0.015). Almost all parameters changed with a tendency towards normal, but differences between TD and CP children remained in all parameters. DISCUSSION: The results confirm that SDR improves functional gait performance in children with CP. However, almost exclusively, parameters of temporal variability were significantly improved, leading to the conjecture that temporal variability and spatial variability may be governed independently by the motor cortex. As a result, temporal parameters of task performance may be more vulnerable to disruption, but also more responsive to treatment success of interventions such as SDR.