The motor repertoire in 3- to 5-month old infants with Down syndrome.

BACKGROUND: Even though Down syndrome is the most common chromosomal cause of intellectual disability, studies on early development are scarce.

AIM: To describe movements and postures in 3- to 5-month-old infants with Down syndrome and assess the relation between pre- and perinatal risk factors and the eventual motor performance.

METHODS AND PROCEDURES: Exploratory study; 47 infants with Down syndrome (26 males, 27 infants born preterm, 22 infants with congenital heart disease) were videoed at 10-19 weeks post-term (median=14 weeks). We assessed their Motor Optimality Score (MOS) based on postures and movements (including fidgety movements) and compared it to that of 47 infants later diagnosed with cerebral palsy and 47 infants with a normal neurological outcome, matched for gestational and recording ages.

OUTCOMES AND RESULTS: The MOS (median=13, range 10-28) was significantly lower than in infants with a normal neurological outcome (median=26), but higher than in infants later diagnosed with cerebral palsy (median=6). Fourteen infants with Down syndrome showed normal fidgety movements, 13 no fidgety movements, and 20 exaggerated, too fast or too slow fidgety movements. A lack of movements to the midline and several atypical postures were observed. Neither preterm birth nor congenital heart disease was related to aberrant fidgety movements or reduced MOS.

CONCLUSIONS AND IMPLICATIONS: The heterogeneity in fidgety movements and MOS add to an understanding of the large variability of the early phenotype of Down syndrome. Studies on the predictive values of the early spontaneous motor repertoire, especially for the cognitive outcome, are warranted.

WHAT THIS PAPER ADDS: The significance of this exploratory study lies in its minute description of the motor repertoire of infants with Down syndrome aged 3-5 months. Thirty percent of infants with Down syndrome showed age-specific normal fidgety movements. The rate of abnormal fidgety movements (large amplitude, high/slow speed) or a lack of fidgety movements was exceedingly high. The motor optimality score of infants with Down syndrome was lower than in infants with normal neurological outcome but higher than in infants who were later diagnosed with cerebral palsy. Neither preterm birth nor congenital heart disease were related to the motor performance at 3-5 months.