EV002 NEUROPHYSIOLOGICAL IMPACT OF HIGH-FREQUENCY SPINAL CORD STIMULATION ON CORTICAL SENSORY PROCESSING IN A LARGE OVINE MODEL

Vishal Bharmauria; Hiroyuki Oya; Yarema Bezchlibnyk; Nour Shaheen; Karim Johari; Can Sarica; Arun Singh; Brian Dalm; Hiroto Kawasaki; Matthew Howard; Andres Lozano; Oliver Flouty

doi:10.1016/j.neurom.2025.09.003

Introduction Spinal cord stimulation (SCS) has evolved from traditional paresthesia-based approaches (P-SCS) to more advanced forms like Dorsal Root Ganglion stimulation (DRG-S), Burst SCS (B-SCS), and High-Frequency SCS (h-SCS), all aimed at optimizing pain relief. While h-SCS is effective in alleviating chronic pain without inducing paresthesia, the mechanisms, particularly at the level of brain oscillations, remain poorly understood. Pain perception involves both spinal and brain-based processes, with oscillations such as gamma (70-150 Hz) linked to sensory processing and theta/beta (4-30 Hz) associated with neural coordination. The interplay between these frequencies could be key in understanding pain modulation. Materials / Methods The study was conducted in four adult sheep under general anesthesia. A 96-contact subdural electrocorticography (ECoG) grid was implanted to monitor cortical oscillations, while a custom neurostimulation probe was placed on the spinal cord. Stimuli were administered through tibial nerve stimulation (TNS) and combined with h-SCS, followed by recording and analyzing ECoG signals to examine low- and high-frequency oscillations. Statistical analyses included mixed-effects models and regression to assess the relationship between low- and high-frequency activity. Results hSCS significantly suppressed high-frequency oscillations in both somatosensory and association cortices (p < 0.05). Low-frequency responses showed variability: most sheep exhibited reductions, but one animal displayed an increase. Regression analysis indicated that low-frequency modulation had a stronger impact on high-frequency suppression in the association cortex, suggesting distinct cortical dynamics in pain modulation. Discussion hSCS led to consistent suppression of high-frequency activity, possibly through mechanisms such as reduced local inhibition or desynchronization of neuronal populations, which may contribute to pain relief. Low-frequency oscillations, crucial for attentional control, showed more significant modulation in the association cortex, suggesting its key role in integrating sensory and cognitive aspects of pain. The study highlights how hSCS may normalize cortical activity, reducing the salience of pain. Conclusions hSCS suppresses high-frequency cortical oscillations and modulates low-frequency activity, likely contributing to its analgesic effects. The association cortex plays a significant role in regulating this oscillatory interplay, suggesting its involvement in sensory integration and pain perception. These findings offer insights into how hSCS alters brain activity to manage pain, pointing to potential therapeutic strategies for chronic pain management.

EV002 NEUROPHYSIOLOGICAL IMPACT OF HIGH-FREQUENCY SPINAL CORD STIMULATION ON CORTICAL SENSORY PROCESSING IN A LARGE OVINE MODEL

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