Pilot use of the early motor repertoire in infants with inborn errors of metabolism: outcomes in early and middle childhood.

BACKGROUND: Predicting later outcome in neonates presenting with severe inborn errors of metabolism (IEM) is difficult. The assessment of the early motor repertoire is a reliable method of evaluating the integrity of the central nervous system in young infants. This method is based on an age-specific qualitative assessment of general movements (GMs, 0-8 weeks of age), fidgety movements (FMs) and the concurrent motor repertoire (9-20 weeks of age).

AIM: To determine the quality of the early motor repertoire (at 0-20 weeks post term age) in relation to later neurological outcome in infants with severe IEM.

STUDY DESIGN: Prospective cohort study. The quality of the motor repertoire was assessed from serial videotape recordings.

SUBJECTS: Five infants with IEM. Four presented with a severe IEM in the neonatal period: an undefined gluconeogenesis defect, propionic acidemia, arginosuccinate synthetase and arginosuccinate lyase deficiency. One neonate was antenatally diagnosed with arginosuccinate synthetase deficiency.

OUTCOME MEASURES: Outcome at the age of at least 18 m was determined by neurological examination and developmental tests.

RESULTS: All infants initially had abnormal GMs: hypokinesia, followed by GMs of a poor repertoire. The quality of the early motor repertoire normalised in 3 infants, and remained abnormal in 2. The more severe and persistent abnormalities of the motor repertoire were considered with the more abnormal neurological and developmental scores, later on.

CONCLUSIONS: The quality of the early motor repertoire might be related to later neurological outcome in infants with inborn errors of metabolism.