The Babinski Reflex is a normal response in infants up to the age of 2, in which the big toe extends upwards and backwards, while the other toes fan outwardly; however, in adults a positive Babinski Sign is pathological and often indicative of severe damage to the central nervous system.
In order to test for a Babinski Sign or Babinski Response: firmly rub the lateral aspect of the sole of the foot with a firm (but blunt) instrument, such as the back of a pen. The pen should be rubbed from one end of the sole of the foot over the curve and through to the toes. This will elicit the following three potential responses:
Extension of the big toe, in which the big toe extends upwards, while the other toes curl outwards. In infants up to the age of 2 this is a normal primitive response and is associated with the under-developed or immature central nervous system. With an Adult however, this is a pathological response, indicating severe damage to the Central Nervous System.
No Response: Indicates damage to the peripheral nervous system, muscles, or tendons within the region.
Flexion: the toes all curve inwards. This is the normal response produced in healthy adults with a fully developed and functional central nervous system.
Comparison of the Babinski Sign in Adults and Infants
In adults the Babinski Sign can indicate upper motor neuron diseases, such as lesions, which affect the corticospinal tract. The cause of this damage can be varied, however, a Positive Babinski Sign will often be the only indication of upper motor neuron disease, and will cause a Neurologist to consider other neurological investigations, such as Lumbar Punctures, MRIs and CT scans to determine cause and treatment. In infants, an extension response, or Positive Babinski response is common because the corticospinal pathway is not fully myelinated, which means that messages are not conducted through the neurological pathway as rapidly, and consequently, the primitive reflex is not inhibited by the cerebral cortex. The extensor response changes to a flexion response during the first 1-2 years of life, depending on natural development of the central nervous system.
What is the significance of a positive Babinski’s sign for paramedics assessing a patient?
An adult patient who is exhibiting a positive Babinski’s sign is likely to have severe damage to the central nervous system. However, as a paramedic, this is just one means of highlighting this fact, but should not change a paramedic’s treatment of the patient. However, it is important to document its presense so that it can be reviewed by a neurosurgeon in hospital. A neurogsurgeon may also take a positive Babinski’s sign into account, in conjunction with many other factors and tests, when determining possible end of life decisions in intensive care.