Functional Ultrasound Imaging Reveals Activation Properties of Clinical Spinal Cord Stimulation Therapy Programming

Area of Science:

• Neuroscience
• Biomedical Engineering
• Pain Management

Background:

• Spinal cord stimulation (SCS) is a key treatment for chronic neuropathic pain.
• Investigating SCS-induced neural activation patterns in the spinal cord (SC) has been methodologically challenging.
• Functional ultrasound imaging (fUS) offers high-resolution monitoring of hemodynamic changes linked to neural activity.

Purpose of the Study:

• To utilize fUS for detailed investigation of SCS neuromodulation patterns.
• To assess SCS-induced activation in the superficial dorsal horn (SDH) using fUS.
• To compare hemodynamic responses across various clinical SCS paradigms in a large animal model.

Main Methods:

• Functional ultrasound imaging (fUS) was employed to detect spinal blood volume (∆SBV) changes.
• Clinical SCS leads were implanted in an ovine model (T12-L1) for stimulation and recording.
• Hemodynamic activation patterns were mapped across two vertebral segments for different SCS modes at varying amplitudes.

Main Results:

• SCS stimulation induced significant, pattern-specific activation in the SDH across vertebral segments.
• Increased amplitude led to greater magnitude and volume of ∆SBV, maximal beneath active electrodes.
• Multiphase SCS therapy resulted in the largest area and greatest depth of ∆SBV, followed by multi-frequency and burst modes.

Conclusions:

• fUS effectively measures SCS neural response patterns in pain-processing laminae of a large animal model.
• Hemodynamic responses varied significantly with SCS therapy mode.
• Multiphase stimulation provided superior area coverage and depth of response compared to other SCS types.