In infants up to 18 months, which reflex finding is considered normal?

In infants up to 18 months, which reflex finding is considered normal?

• A. Positive Babinski sign (toes fan upward)
• B. Negative Babinski sign
• C. Plantar reflex
• D. Moro reflex

Answer: (A)

Infants have several primitive reflexes because the nervous system is still maturing and the corticospinal tract isn’t fully myelinated yet. The Babinski response, where stroking the lateral sole causes the big toe to dorsiflex and the other toes to fan upward, is a normal finding in infants up to about 12–24 months, with 18 months commonly cited. This positive sign reflects immature inhibitory pathways; as myelination progresses, the response shifts to toe curling downward and the Babinski sign disappears. So, this pattern—toes fanning upward when the sole is stroked—is what you’d expect in an infant up to roughly 18 months. By around 18 months and older, the absence of that fanning (toe curling downward) becomes more typical. Other reflexes described, like a Moro reflex persisting beyond the typical 4–6 months, or a lack of Babinski when one would still expect a positive sign for age, would be out of the ordinary for this developmental window.

Infants have several primitive reflexes because the nervous system is still maturing and the corticospinal tract isn’t fully myelinated yet. The Babinski response, where stroking the lateral sole causes the big toe to dorsiflex and the other toes to fan upward, is a normal finding in infants up to about 12–24 months, with 18 months commonly cited. This positive sign reflects immature inhibitory pathways; as myelination progresses, the response shifts to toe curling downward and the Babinski sign disappears.

So, this pattern—toes fanning upward when the sole is stroked—is what you’d expect in an infant up to roughly 18 months. By around 18 months and older, the absence of that fanning (toe curling downward) becomes more typical. Other reflexes described, like a Moro reflex persisting beyond the typical 4–6 months, or a lack of Babinski when one would still expect a positive sign for age, would be out of the ordinary for this developmental window.