Is the Babinski sign present at birth?

Is the Babinski sign present at birth?

• A. Yes, and it remains positive through early childhood
• B. Yes, but it disappears by 1 year
• C. No, it is never present
• D. It is only present in preterm infants

Answer: (B)

The undoing concept here is that some infant reflexes are normal while the nervous system is still maturing. The Babinski response is one of those. In newborns, stroking the sole causes the big toe to extend upward with the other toes fanning out—this is called a positive Babinski sign. It happens because the corticospinal pathways are not fully myelinated yet. As the nervous system matures over the first year, this reflex transitions to the adult pattern of toe flexion, and the Babinski sign disappears usually by about one year of age. So saying it’s present at birth but disappears by one year fits the typical developmental trajectory. If the sign persisted beyond infancy, or appeared later in life, that would point to an upper motor neuron issue. The other options aren’t correct because the reflex is indeed present in newborns, it does not stay positive through early childhood, and it’s not exclusive to preterm infants.

The undoing concept here is that some infant reflexes are normal while the nervous system is still maturing. The Babinski response is one of those. In newborns, stroking the sole causes the big toe to extend upward with the other toes fanning out—this is called a positive Babinski sign. It happens because the corticospinal pathways are not fully myelinated yet. As the nervous system matures over the first year, this reflex transitions to the adult pattern of toe flexion, and the Babinski sign disappears usually by about one year of age. So saying it’s present at birth but disappears by one year fits the typical developmental trajectory.

If the sign persisted beyond infancy, or appeared later in life, that would point to an upper motor neuron issue. The other options aren’t correct because the reflex is indeed present in newborns, it does not stay positive through early childhood, and it’s not exclusive to preterm infants.