Dynamic Detection of Spinal Cord Position During Postural Changes Using Near-Infrared Reflectometry

Area of Science:

• Biomedical Engineering
• Neuroscience
• Medical Devices

Background:

• Spinal cord stimulator electrode position is critical for effective neuromodulation.
• Motion artifacts can lead to suboptimal, inefficient, or insufficient stimulation.
• Adaptive stimulation aims to adjust parameters based on real-time position data.

Purpose of the Study:

• To demonstrate near-infrared (NIR) reflectometry for real-time spinal cord position measurement.
• To facilitate closed-loop adaptive stimulation during static and dynamic conditions.
• To investigate forces influencing spinal cord position.

Main Methods:

• A miniature NIR sensor array was implanted in the epidural space of a human cadaver.
• Spinal cord position was measured using NIR reflectometry during controlled rotation.
• Reflectometry data was correlated with gantry position and velocity.

Main Results:

• NIR reflectometry identified gravitational force as key in static positions.
• Centripetal force was found to be the primary determinant of spinal cord position during dynamic motion.
• Reflectometry data correlated well with a geometric model of spinal cord precession.

Conclusions:

• Spinal cord position is influenced by forces like centripetal force during dynamic motion.
• Indirect methods for estimating spinal cord position have limitations.
• NIR reflectometry provides a direct, real-time measure of spinal cord position for adaptive stimulation.