Medical Student University of Southern California, Keck School of Medicine Los Angeles, California, United States
Disclosure(s):
Wooseong Choi, BS: No financial relationships to disclose
Introduction: Despite the spinal cord's role in integrating sensory, motor, and autonomic functions, its functional architecture remains poorly understood. While restorative attempts, such as spinal cord stimulation, have been expanding in use, the underlying mechanisms are mostly unknown. Research on the functional anatomy of the human spinal cord has been limited due to susceptibility to artifacts and technical challenges of neuroimaging modalities. Recently, functional ultrasound imaging (fUSI) was introduced as a breakthrough modality for large-scale recordings of neural activity. This study reports the first in-human assessment of the spinal cord’s functional response to epidural spinal cord stimulation (ESCS) using fUSI.
Methods: In a single-trial intraoperative experimental setup, four patients underwent T10 partial laminectomy and implantation of SCS paddle lead for the treatment of chronic back pain. A functional ultrasound acquisition system (Iconeus One) was used to acquire fUSI of the spinal cord via a transducer probe inserted through the laminar openings. A stimulation protocol of 10 ON-OFF cycles (30s ON, 30s OFF), was applied during the recording.
Results: Our findings demonstrate a spatiotemporal modulation of the human spinal cord circuitry after ESCS that has not been previously identified, with stimulation-induced spinal cord states that can be decoded from fUSI images after a single trial (accuracy: 84.0±11.4%; 98.3% optimized accuracy across patients). We identify spatial regions affected by the stimulation protocol and show that the most informative content for decoding ESCS induced states is in the small arterioles and capillaries.
Conclusion : This first in-human study is significant as it provides analytical capabilities to assess neural activity modulations indirectly coupled to blood-flow changes with a new level of precision in-vivo. Our ability to decode spinal cord states in a single trial is novel and opens avenues to understand the functional anatomy, dysfunction, and effects of neuromodulation – ultimately vital for developing real-time closed-loop neurorehabilitation systems.
