Paired associative stimulation with a high-intensity cortical component and a high-frequency peripheral component in treatment of neuropathic pain after incomplete spinal cord injury - a pilot trial.

STUDY

DESIGN

Prospective interventional sham-controlled pilot study.

OBJECTIVES

To investigate the effect of motor-tract paired-associative stimulation consisting of high-intensity transcranial magnetic stimulation and high-frequency electric stimulation of peripheral nerves (high-PAS) on moderate-to-severe upper limb neuropathic pain in patients with incomplete spinal cord injury compared with sham treatment in the same patients.

SETTING

BioMag Laboratory, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

METHODS

High-PAS was applied for 4 weeks to 5 patients with incomplete, non-traumatic SCI and chronic neuropathic pain in upper limb(s). Median, ulnar, and radial nerves of the more painful hand were stimulated. The same patients also received sham stimulation for 4 weeks. Pain was measured with Verbal Rating Scale weekly and with Brief Pain Inventory before and after both stimulation periods and after follow-up of 8 weeks.

RESULTS

Clinically significant relief in pain was not achieved with high-PAS or sham treatment.

CONCLUSIONS

In this pilot study, clinically significant pain relief was not observed with high-PAS compared with sham treatment. Larger studies are needed to confirm these findings. Nevertheless, pain is not a contraindication for high-PAS in rehabilitation. The previously reported positive effect on milder neuropathic pain may be due to improved muscle activity, different pain types, or placebo effect. High-PAS targeting sensory tracts instead of motor tracts merits further investigation for pain treatment.

TRIAL REGISTRATION: clinicaltrials.gov, ID NCT05362422.