Muscle tone and pain in children with spastic cerebral palsy

Children with spastic cerebral palsy (CP) often experience pain, but the relationship between pain and increased muscle tone is not well understood. This study used data from the Norwegian Quality and Surveillance Registry for Cerebral Palsy (NorCP) to examine whether clinically measured muscle tone is associated with pain, pain intensity, and the impact of pain on sleep and activities of daily living (ADLs). Muscle tone refers to how much resistance there is when a limb is moved passively, and it was assessed using the Modified Ashworth Scale. The study included 1188 children with spastic CP aged 0 to 17 years. Pain during the previous 4 weeks was reported by 41% of the participants. Pain was more common in older children, those with bilateral spastic CP, and those with more severe gross (higher GMFCS level) and fine motor (higher MACS level) impairments. The lower limbs were the most frequently reported pain location. Among children with pain, one in four (25%) were reported to have pain interfering with sleep, and more than half (53%) were reported to have pain interfering with daily activities. Children with the most severe motor impairments were more likely to experience higher pain intensity and greater interference with sleep and ADLs. Nearly half of the children had at least one muscle group with significantly increased muscle tone. However, increased muscle tone showed only a modest association with greater pain intensity and with pain interfering with ADLs.