A longitudinal analysis of selective motor control during gait in individuals with cerebral palsy and the relation to gait deviations

Abstract

Objective: To investigate longitudinal changes in selective motor control during gait (SMCg) in individuals with cerebral palsy (CP), and to assess if they are related to changes in gait deviations.

Method: Twenty-three children/adolescents with spastic CP (mean ± SD age = 9.0±2.5 years) and two 3D gait assessments (separated by 590±202 days) with no interim surgical intervention, were included. SMCg was assessed using muscle synergy analysis to determine the dynamic motor control index (walk-DMC). Gait deviation was assessed using the Gait profile score (GPS) and Gait variable scores (GVS).

Results: There were no mean changes in walk-DMC score, GPS or GVS between assessments. However, changes in walk-DMC scores in the more involved leg related to changes in hip flexion-extension and hip internal-external GVS (rp = -0.56; p = 0.017 and rp = 0.65; p = 0.004, respectively).

Conclusions: On average, there were no significant longitudinal changes in SMCg. However, there was considerable variability between individuals, which may relate to changes in hip joint kinematics. This suggests that a combination of neural capacity and biomechanical factors influence lower limb muscle co-activation in individuals with CP, with a potential important role for the hip muscles. These findings highlight the importance of taking an individualized approach when evaluating SMCg in individuals with CP.

Fig 1. Overview of change in walk-DMC scores between the two assessments.

In both figures, participant numbers have been ordered from greatest improvement to greatest deterioration in walk-DMC scores, with the order of participant numbers differing between the two figures. Walk-DMC- the walking dynamic motor control index.

Fig 2. Movement analysis profile for the more involved leg (n = 18).

The numbers within the bars represent the mean and the lines are the 95% confidence intervals. Dark colours—first assessment, light colours—second assessment. Ant- anterior, Post- posterior, Flex- flexion, Ext- extension, DF- dorsiflexion, PF- plantarflexion, Add- adduction, Abd- abduction, IR- internet rotation, ER- external rotation.

Fig 3. The relationship between the changes in the walk-DMC to the hip flexion/extension GVS (a), the relationship between the changes in the walk-DMC to the hip internal/external rotation GVS (b).

All relationships were in the more involved leg. Walk-DMC- the walking dynamic motor control index, GVS- gait variable score.

Fig 4. Overview of change in hip flexion/extension and hip internal/external rotation GVS values, between the two assessments.

In both figures, participant numbers have been ordered from greatest improvement to greatest deterioration in the GVS value, with the order of participant numbers differing between the two figures. GVS- gait variable score.