Development of clinical signs in low risk term born infants with neonatal hyperexcitability

BACKGROUND: Several studies have reported on neonatal tremors or "jitteriness" or, as described by Precthl "hyperexcitability syndrome" including tremors and increased resistance to passive movement. AIM: To describe the evolution of signs and the outcome at one year in low risk term born infants with neonatal tremors persisting beyond 10days. SUBJECTS: 84 low risk term born neonates with tremors at birth and persisting after 10days, underwent a longitudinal neurological assessment paying attention to the evolution of tremors and increased resistance to passive movement. RESULTS: At 1month 74 of the 84 infants had persistent tremors, isolated in 27 or associated with increased resistance to passive movement in the other 47. The remaining 10 had isolated increased resistance to passive movement and none had a normal assessment. The percentage of infants with a normal assessment progressively increased at 6, 9 and 12months (34.5%, 77%, 93% respectively). CONCLUSION: Our data suggest that neonatal tremors can have a variable evolution and rate of resolution, with 70% of recovery by 9months with a normal outcome at 24months in all. The risk of persistence of signs (at 12months) in infants with either isolated tremors or increased resistance to passive movements is lower than in the subgroup with both signs at one month.