Effects of Noninvasive Low-Intensity Focus Ultrasound Neuromodulation on Spinal Cord Neurocircuits In Vivo

Evidence-Based Complementary and Alternative Medicine, 2021 · DOI: https://doi.org/10.1155/2021/8534466 · Published: November 27, 2021

Neurology Medical Imaging

Simple Explanation

This study explores whether low-intensity focused ultrasound (LIFU) can stimulate spinal cord neurocircuits in rats. The researchers applied LIFU to the lumbar region of the spinal cord and measured muscle contractions using electromyography (EMG). The study found that LIFU stimulation at certain intensities could activate these neurocircuits, leading to muscle contractions. However, when the intensity was too high, it resulted in spinal cord damage. These findings suggest that LIFU can be a safe and effective method for spinal cord neuromodulation if the intensity is carefully controlled.

Study Duration

Not specified

Participants

48 Sprague Dawley rats

Evidence Level

Level 5, Animal Study

Key Findings

1
LIFU stimulation at intensities greater than 0.5 MPa induced soleus muscle contraction and increased EMG amplitudes, indicating activation of spinal cord neurocircuits.
2
LIFU stimulation at 3.0 MPa led to spinal cord damage, decreased somatosensory evoked potential (SEP) amplitudes, and caused coagulation necrosis and neuronal loss.
3
LIFU stimulation with an irradiation intensity ≤1.5 MPa is a safe neurostimulation method for the spinal cord.

Research Summary

The study investigates the effects of low-intensity focused ultrasound (LIFU) on spinal cord neurocircuits in rats. LIFU stimulation of the L4-L5 spinal cord segments enhanced soleus muscle contraction, as measured by EMG. The researchers assessed neuronal activation, injury, and neuromotor function using a variety of methods, including EMG, western blotting, immunoﬂuorescence, and behavioral assessments. The results indicate that LIFU can activate spinal cord neurocircuits, but high intensities can cause damage, suggesting that LIFU stimulation with an irradiation intensity ≤1.5 MPa is a safe neurostimulation method for the spinal cord.

Practical Implications

Therapeutic Potential

LIFU could be a non-invasive method for spinal cord stimulation to treat chronic spine-related conditions.

Safety Considerations

The intensity of LIFU stimulation must be carefully controlled to avoid causing damage to the spinal cord.

Further Research

Future studies should investigate the detailed mechanisms of LIFU action and the long-term effects of LIFU stimulation on the spinal cord.

Study Limitations

1
The detailed mechanism of how LIFU activates spinal cord neurocircuits is unknown.
2
Further experiments are needed to clarify the mechanisms underlying spinal cord injuries at higher LIFU intensities.
3
The study did not determine how long the effects of LIFU stimulation are maintained.

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