Characterization of spasticity in cerebral palsy: dependence of catch angle on velocity.
OBJECTIVE
To evaluate spasticity under controlled velocities and torques in children with cerebral palsy (CP) using a manual spasticity evaluator.


METHODS
The study involved 10 children with spastic CP (six males, four females; mean age 10 y 1 mo, SD 2 y 9 mo, range 7-16 y; one with quadriplegia, six with right hemiplegia, three with left hemiplegia; Gross Motor Function Classification System levels I [n=2], II [n=3], III [n=2], IV [n=2], and V [n=1]; Manual Ability Classification System levels II [n=5], III [n=4], and V [n=1]) and 10 typically developing participants (four males, six females; mean age 10 y 3 mo, SD 2 y 7 mo, range 7-15 y). Spasticity and catch angle were evaluated using joint position, resistance torque, and torque rate at velocities of 90 degrees, 180 degrees, and 270 degrees per second, controlled using real-time audio-visual feedback. Biomechanically, elbow range of motion (ROM), stiffness, and energy loss were determined during slow movement (30 degrees/s) and under controlled terminal torque.


RESULTS
Compared with typically developing children, children with CP showed higher reflex-mediated torque (p<0.001) and the torque increased more rapidly with increasing velocity (p<0.001). Catch angle was dependent on velocity and occurred later with increasing velocity (p=0.005). Children with CP showed smaller ROM (p<0.05), greater stiffness (p<0.001), and more energy loss (p=0.003).


CONCLUSIONS
Spasticity with velocity dependence may also be position-dependent. The delayed catch angle at higher velocities indicates that the greater resistance felt by the examiner at higher velocities was also due to position change, because the joint was moved further to a stiffer position at higher velocities.
Wu
Yi-Ning
YN
Rehabilitation Institute of Chicago, IL 60611, USA.
Ren
Yupeng
Y
Goldsmith
Ashlee
A
Gaebler
Deborah
D
Liu
Shu Q
SQ
Zhang
Li-Qun
LQ
D000293:Adolescent; D001132:Arm / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D002547:Cerebral Palsy / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D002648:Child; D004185:Disability Evaluation; D004576:Electromyography; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D009048:Motor Skills / Q000502:physiology; D009128:Muscle Spasticity / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D011597:Psychomotor Performance / Q000502:physiology; D011782:Quadriplegia / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D012018:Reflex / Q000502:physiology; D015203:Reproducibility of Results; D013647:Task Performance and Analysis