The Babinski reflex: a neurological plantar sign, normal in infants but abnormal in adults. What it reveals and how it's tested.
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The same gesture, a stroke under the foot, means something completely different in a baby than in an adult. That contrast is exactly what makes neurology's most famous sign so useful.
Hello to you, movement professional,
The Babinski reflex holds a place of its own among these reflexes, and this needs saying right away: it is a clinical sign, a tool the physician uses to assess one specific nerve pathway, rather than an archaic reflex you would integrate through exercises. So this page is a factual reference, not a method. Here we will tell apart what is normal from what is not, and explain what this sign really says.
It all starts with the same gesture: you stimulate the skin of the sole, along the outer edge, from the heel toward the toes. In an infant, the response is an upward extension of the big toe, often with the other toes fanning out. This is perfectly normal at that age, while the nerve pathway carrying motor commands finishes maturing.
In an older child and in a healthy adult, this pathway is mature, and the normal response reverses: the toes curl down toward the sole. When, in an adult, the big toe rises instead of going down, we speak of a positive Babinski sign. The same movement is unremarkable in a baby and meaningful in an adult. This reversal is what makes the test so valuable.
A positive Babinski sign in an adult is a marker of damage to the pyramidal tract, the pathways that connect the motor cortex to the motor neurons of the spinal cord and command voluntary movement. When these pathways are injured, the mature plantar response, flexion, no longer happens, and the primitive extension reflex returns. That is why this sign is one of the most sought after in neurology: it is simple, quick, and it points toward what is called a pyramidal syndrome.
Historically, this sign has helped distinguish truly neurological conditions from other clinical pictures. It shows up in widely varied situations that share one thing: they affect these command pathways. After a stroke, it appears on the side opposite the lesion; it occurs in multiple sclerosis, and in certain degenerative diseases of the nervous system. Its presence is never a diagnosis on its own; it is one sign among others that the physician interprets as part of a whole.
The exam is simple. The person lies down, leg slightly bent, foot relaxed. The examiner runs a blunt-tipped object, without pricking, along the outer edge of the sole, from the heel toward the toes, then watches the big toe's response: flexion is the negative sign, and therefore reassuring; a slow upward extension is the positive sign.
There are, in fact, several ways to look for the same information when the response is unclear, and they bear the names of those who described them. The Chaddock maneuver stimulates the outer edge of the foot below the ankle bone, the Oppenheim slides along the inner surface of the shin, and the Gordon squeezes the calf. All of them aim to provoke the same extension of the big toe when the pyramidal pathway is affected. These are clinician's tools, not exercises to repeat at home.
Let's come back for a moment to the infant, because that is where this sign meets the story of the other reflexes. The plantar reflex in extension is normal during the early period of life, and it gradually integrates as the pyramidal pathway matures, usually within the first two years. Its disappearance is therefore, as with the other archaic reflexes, a sign that the nervous system is developing well.
That is the only thing the infant's plantar reflex shares with the adult's Babinski sign: one and the same nerve pathway, read at two moments in life. In a baby, its extension says everything is on track. In an adult, it says you should look for why a mature pathway no longer responds normally. Confusing the two would be a mistake, and that is precisely why this page exists.
The answer fits in one sentence: this is a physician's job. A positive Babinski sign in an adult warrants an opinion and, most often, further tests, first and foremost imaging of the brain or spinal cord to look for the cause. There is no such thing as "Babinski sign rehabilitation": you treat what produces the sign, never the sign on its own. That is exactly why this reflex does not belong to a movement-based reprogramming approach, unlike the archaic reflexes we cover elsewhere.
If you are a movement professional and you notice such a sign in an adult, the right move, the only one, is to refer to a physician. That too is rigor: knowing where our field ends.
It is the big toe's response to stimulation of the sole. In an adult, an extension of the big toe, the positive Babinski sign, reflects damage to the pyramidal tract, the pathway of voluntary motor command.
In an infant, the pyramidal pathway is not yet mature, and extension of the big toe is expected. In an adult, this pathway is mature and the normal response is flexion of the toes; extension then becomes a sign of damage.
Any damage to the pyramidal tract: stroke, multiple sclerosis, certain degenerative diseases, or spinal cord lesions. The sign points the way; it is not enough to make a diagnosis.
It integrates gradually as the pyramidal pathway matures, most often within the first two years. Its disappearance is a marker of normal neurological development.
See a physician. A positive sign in an adult leads to a specialist opinion and to tests, in particular imaging. There is no "integration" exercise for this sign: the cause is what gets addressed, not the sign.
To place the infant's normal plantar reflex among the other reflexes of the very young child, read our pillar guide on archaic reflexes.
By the LabO RNP team
To place the infant's normal plantar reflex among the other reflexes of the very young child, see the guide to archaic reflexes.
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