The crossed extensor hallucis response in neurological disorders; an electromyographic analysis

Area of Science:

• Neuroscience
• Human Physiology
• Neurology

Background:

• The Babinski sign is a well-established neurological reflex indicating upper motor neuron lesions.
• The crossed up-going toe (CUT) sign is another reflex response observed in neurological assessments.
• Understanding the electromyographic (EMG) activity associated with these signs is crucial for differential diagnosis.

Purpose of the Study:

• To investigate and compare the electromyographic activity of leg muscles during the elicitation of the CUT sign.
• To differentiate the neural pathways responsible for the CUT sign versus the Babinski sign.
• To identify specific differences in muscle activation patterns between normal subjects and patients exhibiting the CUT sign.

Main Methods:

• Electromyographic (EMG) activity was recorded from multiple leg muscles.
• EMG data were collected during the elicitation of the CUT sign in patients.
• Comparisons were made with EMG data from the Babinski sign and in healthy control subjects.

Main Results:

• Distinct patterns of muscle activation and distinct neural pathways were identified for the CUT and Babinski signs.
• Patients with a positive CUT sign showed quantitative differences in the coactivation of distal leg muscles compared to normal subjects.
• The observed differences in CUT-positive patients were quantitative, not qualitative changes in reflex patterns.

Conclusions:

• The CUT sign and Babinski sign are mediated by different neural pathways.
• The elicitation of the CUT sign in patients is characterized by altered, but not fundamentally different, reflex patterns of distal leg muscle coactivation compared to normal individuals.