Focused Ultrasound for Motor Neuron Modulation of the Spinal Cord


Key Points

  • A Johns Hopkins University research team conducted a preclinical study evaluating the ability of low-intensity ultrasound (LIUS) to modulate motor neurons in an exposed spinal cord at T11-T12.
  • The LIUS significantly decreased electrical signals from the spine to the treated hindlimb, but not the untreated forelimb.
  • Researchers hope these data may eventually be useful for treating spinal-generated dyskinesias, spinal segmental myoclonus, or stiff-man syndrome.

Low-Intensity Pulsed Ultrasound Neuromodulation of a Rodent’s Spinal Cord Suppresses Motor Evoked Potentials

The multi-disciplinary HEPIUS Innovation Laboratory at Johns Hopkins University School of Medicine is affiliated with Departments of Neurosurgery, Biomedical Engineering, Mechanical Engineering, Electrical and Computer Engineering, and Anesthesiology and Critical Care Medicine. A HEPIUS-based collaborative research team recently conducted a preclinical study evaluating the ability of low-intensity ultrasound (LIUS) to modulate motor neurons in the exposed spinal cord at T11-T12.

The team measured the amplitude of motor evoked potentials (MEPs, which are electrical signals) from the spinal cord to the limbs each minute for either 5- (group 1) or 10-minutes (group 2) of sonication plus 5 additional minutes after the sonication period. The sonication parameters included a center frequency of 500 kHz, 500 µs tone burst duration, and a 50% duty cycle. In both groups, the ultrasound significantly decreased MEP amplitude during sonication in the treated hindlimb, but not the untreated forelimb. Both treatment groups also had a corresponding gradual return to baseline. Tissue and temperature analyses showed that the treatment did not damage the tissue, and there was minimal change in tissue temperature during the sonications.

“When I started my PhD studies back in 2010, I remember receiving advice about how ultrasound was an old field, with the innovation peak of the field during the 1970s,” said Amir Manbachi, PhD, an assistant professor of neurosurgery, biomedical engineering, mechanical engineering, electrical and computer engineering, anesthesiology and critical care medicine, co-director and founder of the HEPIUS Innovation Laboratory, and the study’s senior author. “When I see the exciting work of colleagues, including studies like this, I am reminded of the untapped innovation that lies ahead in this field. It is moments like this that make me appreciate the promise of ultrasound in medicine and why what we do is important.”

Amir Manbachi, PhD, and Nicholas Theodore, MD, MS

Dr. Manbachi and the team, including several other academic laboratories led by Nicholas Theodore, MD, MS (neurosurgeon), Nitish Thakor, PhD (neuro-engineer), and Joshua Doloff, PhD (biomedical engineer), concluded that the LIUS application to the spinal cord temporarily suppressed the MEP signals that were caudal to the location of the sonication. The group speculated that this treatment may be useful for treating spinal-generated movement disorders, which are driven by excessive excitation of spinal neurons (e.g., dyskinesias, spinal segmental myoclonus, stiff-man syndrome).

Dr. Theodore best summarized this work by saying that, “The prospect of ultrasound for neuromodulation is no longer science fiction!”

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