Neuromodulation and Implantable Devices
Core concepts
Spinal cord stimulation (tonic, high-frequency, burst, closed-loop), dorsal root ganglion stimulation, and peripheral nerve stimulation. Understand indications (persistent radicular or neuropathic pain after failed conservative care), trial-to-implant pathway, and programming concepts. Intrathecal drug delivery is the other major implantable modality, with its own drug and dosing considerations.
Device selection and trials
Selection depends on pain distribution and mechanism: DRG stimulation for focal, dermatomal pain; SCS for broader limb pain; PNS for well-localized mononeuropathy. A successful trial requires predefined criteria (for example, substantial coverage and functional improvement).
Traps
- Implanting without an adequate trial or clear coverage of the painful area.
- Ignoring MRI compatibility and diathermy restrictions.
- Missing infection and erosion signs; device infection can be deep and requires prompt evaluation.
- Overlooking programming troubleshooting before revising hardware.
Worked rule of thumb
Define trial success in advance (coverage of the pain region plus functional gain) and only implant when coverage is reproducible. For suspected malfunction, check programming and impedance before surgical revision.
Safety
Counsel on MRI conditions, magnet interactions, and the need to report device-related symptoms.