From the Guidelines
The Babinski reflex is a neurological sign that indicates damage to the nerve pathways that connect the brain and spinal cord, specifically the corticospinal tract, and its presence in adults suggests an abnormality in the central nervous system, as noted in patients with hepatic encephalopathy 1. When present in adults, it suggests an abnormality in the central nervous system, such as those seen in hepatic encephalopathy, where motor system abnormalities, including a positive Babinski sign, can be observed 1.
Key Points to Consider
- The Babinski reflex is normally present in infants up to about 2 years of age as their nervous systems are still developing, but its presence in older children and adults is abnormal.
- To test for this reflex, a healthcare provider strokes the sole of the foot from the heel toward the toes with a blunt object.
- In a normal adult response, the toes curl downward (plantar flexion), but a positive Babinski sign occurs when the big toe moves upward (dorsiflexion) while the other toes fan out.
- The Babinski reflex can indicate various neurological conditions, including those associated with hepatic encephalopathy, such as hypertonia, hyper-reflexia, and extrapyramidal dysfunction 1.
Clinical Implications
- The presence of a positive Babinski sign in patients with hepatic encephalopathy may indicate a more severe form of the disease, with significant motor and cognitive impairments 1.
- A thorough neurological examination, including the assessment of the Babinski reflex, is essential in evaluating patients with suspected hepatic encephalopathy, as it can help guide treatment strategies and predict outcomes 1.
From the Research
Definition and Interpretation of Babinski Reflex
- The Babinski reflex, also known as the Babinski sign, is a reflex that involves the contraction of the extensor hallucis longus muscle in response to stimulation of the plantar surface of the foot 2, 3.
- The reflex is indicative of dysfunction of the pyramidal tract, which is a pathway in the central nervous system that controls voluntary movement 2, 3.
- A true Babinski sign denotes dysfunction of the pyramidal tract and should be clearly distinguished from upgoing toes that do not belong to the flexion synergy of the leg 3.
Clinical Significance of Babinski Reflex
- The Babinski sign is a reliable indicator of central nervous system dysfunction, particularly in the pyramidal tract 2.
- The sign can be used to predict cortical lesions of the pyramidal tract, with different patterns of Babinski sign observed in patients with cortical versus sub-cortical lesions 4.
- The Babinski sign has been used in clinical practice for over a century, and its interpretation depends on the assessment of the response in the entire leg, rather than just the toes 3.
Comparison with Other Clinical Signs
- The Babinski sign has been compared to other clinical signs, such as finger and foot tapping, in the diagnosis of corticospinal tract lesions 5.
- While the Babinski sign has a relatively low sensitivity and specificity, finger and foot tapping have been shown to be more reliable and valid tests for diagnosing corticospinal lesions 5.
- The interobserver agreement for the Babinski sign is also lower compared to finger and foot tapping, which may limit its usefulness in clinical practice 5.
Historical Context and Contributions of Joseph Babinski
- Joseph Babinski first described the clinical significance of the Babinski reflex in 1896, and his work laid the foundation for the understanding of the pyramidal tract and its role in motor control 2, 6.
- Babinski's contributions to neurological symptomatology extend beyond the Babinski reflex, and include the description of other clinical signs such as cerebellar asynergy and anosognosia 6.