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Updated: Mar 6, 2026
Electrophysiological Methods to Assess Peripheral Pain Block in an Anesthetized Rat
Published on: November 21, 2025
An Observational Electrophysiologic Study for Optimizing Targeting of Monopolar Lumbar Spinal Foraminal Neural
Philippe Rigoard1, Thomas Yearwood2, Matteo Costanzi3
1PRISMATICS Lab - CIC-IT, INSERM 1402 (Predictive Research and Innovative Strategies for Medical & AdvancedTechnology Integration in Care Systems), CHU de Poitiers, Poitiers, France; Service de neurochirurgie du rachis, chirurgie de la douleur et du handicap, CHU de Poitiers, Poitiers, France; Pprime Institute UPR 3346, CNRS, ISAE-ENSMA, Université de Poitiers, Poitiers, France.
Optimal pain relief from dorsal root ganglion (DRG) stimulation often occurs outside the traditional target zone. This study shows that stimulating surrounding neural structures, not just the DRG, is key for effective pain management.
Area of Science:
- Neurology
- Pain Management
- Neurosurgery
Background:
- The dorsal root ganglion (DRG) is a key target for treating chronic refractory pain.
- Optimal electrode placement for DRG stimulation remains a challenge.
- Current methods target the infrapedicular zone, but clinical data suggest periganglionic structures are also important.
Purpose of the Study:
- To investigate optimal electrode locations for DRG stimulation.
- To determine if periganglionic stimulation improves pain-paresthesia coverage (PPC).
- To compare PPC with anatomical DRG location.
Main Methods:
- Electro-stimulation mapping (ESM) was performed on seven subjects with spinal cord stimulation (SCS) leads.
- 288 paresthesia mappings were analyzed relative to spinal anatomy.
- Electrodes were categorized by location: intraspinal, foraminal, and extraforaminal.
Main Results:
- Optimal PPC occurred within the conventional DRG region for only 25% of electrodes.
- 75% of electrodes with optimal PPC were located outside the defined foraminal zone.
- ESM identified physiological boundaries of the neuro-foramen not visible on standard imaging.
Conclusions:
- Optimal PPC is not consistently achieved by stimulating the DRG directly.
- Stimulation may engage DRG and adjacent neural structures.
- Precise electrode localization is crucial; broader terms like spinal transforaminal stimulation may be more appropriate.
