Myotatic reflex responses of non-disabled children and children with spastic cerebral palsy.

Surface electromyography (EMG) was used to examine lower-extremity myotatic reflex responses following patellar or Achilles tendon taps to normally developing, non-disabled infants and to individuals with cerebral palsy (CP). Reflex irradiation was present in non-disabled infants and infants with CP under two years of age. The only significant differences in myotatic reflex responses between the two groups at this age was the higher amplitude of the directly stimulated muscle of children with CP. After two years the amplitude did not differ between groups. Reflex irradiation, however, was greatly reduced in the non-disabled children but not in the children with cerebral palsy. These findings and those of non-human animal studies indicate the possible neural mechanisms that underlie reflex irradiation of individuals with CP. The potential clinical relevance of these findings is discussed.