From the Guidelines
A positive Babinski sign indicates upper motor neuron dysfunction, suggesting damage to the corticospinal tract in the brain or spinal cord. This abnormal reflex can result from various neurological conditions, including those mentioned in the study by 1, such as TANGO2-related disorders, which can present with positive Babinski sign, spastic Achilles tendons, and multiple joint contractures. The Babinski sign is normally present in infants up to about 12-24 months of age due to incomplete myelination of the corticospinal tracts, but its presence in older children and adults is always pathological.
When testing this reflex, stroking the sole of the foot causes an upward movement of the big toe with fanning of the other toes, rather than the normal downward flexion response. The test is valuable in neurological examinations because it helps localize lesions to the central nervous system rather than peripheral nerves, and can provide important diagnostic information when evaluated alongside other neurological findings.
Some key points to consider when interpreting a positive Babinski sign include:
- The presence of other neurological signs, such as hypertonia, hyper-reflexia, or extrapyramidal dysfunction, as mentioned in the study by 1
- The patient's age and medical history, as the Babinski sign can be a normal finding in infants but is always pathological in older children and adults
- The need for further neurological investigation to determine the underlying cause of the upper motor neuron pathology, as the Babinski sign can result from a variety of conditions affecting the central nervous system.
In terms of morbidity, mortality, and quality of life, a positive Babinski sign can be an indicator of underlying neurological dysfunction that may impact the patient's functional abilities and overall well-being. Therefore, prompt evaluation and management of the underlying condition are essential to improve outcomes and quality of life.
From the Research
Implications of a Positive Babinski Test
A positive Babinski test implies an abnormality in the corticospinal tract, which is a pathway in the central nervous system that controls motor function. The test is used to assess the integrity of this tract and can indicate damage or dysfunction in the brain or spinal cord.
Clinical Significance
- A positive Babinski sign is indicative of pyramidal tract dysfunction, which can be caused by a variety of conditions, including stroke, spinal cord injury, and amyotrophic lateral sclerosis (ALS) 2.
- The sign is characterized by an extensor plantar response, where the big toe extends upwards and the other toes fan out, and is mediated by the extensor hallucis longus muscle 2.
- The presence of a positive Babinski sign can be used to localize central nervous system dysfunction and can be an important diagnostic tool in clinical practice 2.
Relationship to Corticospinal Tract Lesions
- Studies have shown that the Babinski sign is a reliable indicator of corticospinal tract lesions, particularly those affecting the pyramidal tract 3, 4.
- The sign can be used to distinguish between cortical and non-cortical lesions, with patients with cortical lesions showing a different pattern of Babinski sign than those with sub-cortical lesions 5.
- The presence of a positive Babinski sign can also be used to predict the presence of upper motor neuron lesions in conditions such as ALS 4.
Factors Influencing the Occurrence of the Babinski Sign
- The occurrence of the Babinski sign can be influenced by factors such as the level of lesion, spastic muscle tone, and peripheral nerve damage 6.
- In complete spinal cord injury patients, the presence of a positive Babinski sign is connected with spastic muscle tone, while the absence of the sign is frequently due to associated peripheral nerve damage 6.