A stereotypic "elbowing" movement, a possible new primitive reflex in newborns.

The primitive reflexes are brainstem-mediated and play various roles in the child's psychomotor development. The objective of the current study is to describe a new pattern of primitive reflex, noticed in 52 of 81 randomly chosen newborns and young infants during pressing of the subcostal region. Some of them reacted by three-phase stereotypic movement as follows: phase 1: quick adduction of upper arm with flexion of the forearm, with elbow directed toward the site of stimuli, touching the stimulated area; phase 2: abduction and retroflexion of upper arm with the movement of removing the stimulus with the elbow; phase 3: extension and pronation of the forearm. The prevalence of this newly described reflex was 64.2%. The incidence of all three phases together was highest at Day 16 (63.5%); phase 1 was the most frequent at Day 30 (88.5%) in 52 children with positive reflex. At Day 86, only 18.4% of them retained the first phase of the movement and 2% retained the third phase. All reflexes appeared until Day 30. We believe that we have described a new primitive reflex, with all characteristics essential for primitive reflexes. It is definitely involuntary, complex, stereotypic, with decreased incidence over time. Because of the defensive purpose and peculiar manner of this reflex, we named it the "elbowing reflex."