Vibration-induced motor responses of infants with and without myelomeningocele.
BACKGROUND
The severity of myelomeningocele (MMC) stems both from a loss of neurons due to neural tube defect and a loss of function in viable neurons due to reduced movement experience during the first year after birth. In young infants with MMC, the challenge is to reinforce excitability and voluntary control of all available neurons. Muscle vibration paired with voluntary movement may increase motoneuron excitability and contribute to improvements in neural organization, responsiveness, and control.


OBJECTIVE
This study examined whether infants with or without MMC respond to vibration by altering their step or stance behavior when supported upright on a treadmill.


METHODS
This was a cross-sectional study.


METHODS
Twenty-four 2- to 10-month-old infants, 12 with typical development (TD) and 12 with MMC (lumbar and sacral lesions), were tested. Infants were supported upright with their feet in contact with a stationary or moving treadmill during 30-second trials. Rhythmic alternating vibrations were applied to the right and left rectus femoris muscles, the lateral gastrocnemius muscle, or the sole of the foot. Two cameras and behavior coding were used to determine step count, step type, and motor response to vibration onset.


RESULTS
Step count decreased and swing duration increased in infants with TD during vibration of the sole of the foot on a moving treadmill (FT-M trials). Across all groups the percentage of single steps increased during vibration of the lateral gastrocnemius muscle on a moving treadmill. Infants with MMC and younger infants with TD responded to onset of vibration with leg straightening during rectus femoris muscle stimulation and by stepping during FT-M trials more often than older infants with TD.


CONCLUSIONS
Vibration seems a viable option for increasing motor responsiveness in infants with MMC. Follow-up studies are needed to identify optimal methods of administering vibration to maximize step and stance behavior in infants.
Department of Movement Science, School of Kinesiology, University of Michigan, 401 Washtenaw Ave, Ann Arbor, MI 48109-2214, USA. ssaavedr@umich.edu
Sandra L
SL
Saavedra
Caroline
C
Teulier
Beth A
BA
Smith
Byungji
B
Kim
Benjamin D
BD
Beutler
Bernard J
BJ
Martin
Beverly D
BD
Ulrich
D000704:Analysis of Variance; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008591:Meningomyelocele / Q000503:physiopathology* / Q000534:rehabilitation*; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014732:Vibration