Ultrasound-guided spinal stereotactic system for intraspinal implants

Area of Science:

• Neurosurgery
• Medical Imaging
• Biomedical Engineering

Background:

• Precise placement of intraspinal implants is crucial for therapies like intraspinal microstimulation (ISMS).
• Existing methods may lack the accuracy and intraoperative guidance needed for targeting specific spinal cord gray matter regions.

Purpose of the Study:

• To develop and evaluate an image-guided spinal stereotactic system for accurate intraoperative intraspinal microstimulation (ISMS).
• To achieve sub-millimeter accuracy in placing implants within the spinal cord's gray matter.
• To ensure modularity and compatibility with standard surgical tools.

Main Methods:

• Developed a spine-mounted stereotactic system with a 6-degrees-of-freedom micromanipulator.
• Integrated an intraoperative ultrasound imaging technique for electrode alignment and guidance.
• Tested the system's performance in pig models (live and cadaveric) and on benchtop surrogate spinal cords.
• Quantified electrode alignment, implantation depth accuracy, and spatial targeting error within the gray matter.

Main Results:

• The stereotactic system demonstrated rapid setup (<10 minutes) and reliable target access in pigs.
• Ultrasound imaging provided clear contrast between spinal cord gray and white matter.
• Maximal electrode alignment error was ≤ 3.57° and targeting error was 0.2 ± 0.02 mm in bench tests.
• Proof-of-concept ISMS experiment successfully recorded movements and electromyographic responses.

Conclusions:

• An ultrasound-guided spinal stereotactic system was successfully developed and evaluated for precise intraspinal implant insertion.
• The system is compatible with existing spinal instrumentation and enhances confidence in gray matter targeting.
• Intraoperative ultrasound imaging provides critical feedback for implant alignment and placement, suitable for electrodes, drug, or cell injections.