The Babinski reflex is believed to have evolutionary significance, possibly aiding in the development of the infant’s nervous system. It serves as an important marker for neurological function and development in infants. To test the Babinski reflex, a healthcare provider will use a blunt object, often a reflex hammer, to stroke the sole of the baby’s foot from the heel to the toes. The expected response in infants is the upward movement of the big toe and fanning of the other toes.
In infants, the presence of the Babinski reflex is normal and indicates healthy development of the nervous system. This reflex typically disappears by the age of 2 years as the brain and spinal cord mature. However, in adults and older children, the presence of a Babinski sign—an upward movement of the big toe and fanning of the other toes—is abnormal and suggests possible damage to the corticospinal tract, which is a part of the central nervous system that conducts motor control. It can indicate neurological conditions such as multiple sclerosis, stroke, or a brain or spinal cord injury.
The Babinski reflex is named after the French neurologist Joseph Babinski, who first described it in 1896. Like other primitive reflexes, the Babinski reflex offers a glimpse into early human development and the evolutionary mechanisms that help infants respond to their environment. As the infant’s nervous system matures, the Babinski reflex gradually disappears. By the age of 2 years, the normal response to stroking the sole of the foot is a downward movement of the toes, known as the plantar response.