In this pilot study the investigators will use Global Positioning Systems (GPS) to measure walking speed, distances, number of walking events and destinations in ambulatory children with CP following BTX injection to the lower limbs; age and gender matched sibling will be studied as a control group. Outdoor activity will be measured at 1, 3 and 6 months following BTX treatment will be compared to baseline and to those of siblings. Outdoor activity will be correlated with leisure activity preferences and quality of life questionnaires.