Transient tone abnormalities in high risk infants and cognitive outcome at five years.

OBJECTIVE to identify transient tone abnormalities and determine its prevalence in high risk infants and their cognitive outcome at 5 years. DESIGN prospective cohort observational study. SETTING high risk infants discharged from a level II neonatal unit in a 12 month period, and followed upto 5 years. METHODS High risk infants and normal controls were assessed for abnormalities of tone using the method described by Amiel Tison at 3, 6, 9, 12 months. An IQ by Stanford Binet method and a preschool inventory by Ayres, Bobath was done at 5 years. Those infants who had normal tone at 6 and 12 months were called normal high risk (HR) group and those who had abnormalities at 6 months, which disappeared at 12 months, were called the transient tone abnormalities (TTA) group. RESULTS out of 190 high risk infants, 113 were normal HR and 67 (35.2%) were labeled as TTA. Ten infants with cerebral palsy had abnormal tone throughout the first year. Controls had normal tone throughout the follow-up period. Although there was no difference in the IQ of the TTA group (98.5 ± 12.4) and the normal HR (99.1 ± 13.1) group, it was significantly less (P=0.04) than that of controls (106.1 ± 9.1). Preschool inventory in TTA children showed poor language development (P=0.014). CONCLUSION many of the tone abnormalities detected at 6 months resolve by 12 months, hence a hasty diagnosis of cerebral palsy should not be made. High risk infants with transient tone abnormalities have a normal cognitive outcome at 5 years, except for poor language skills.