Scrambler therapy for treatment of poststroke pain.

Objective: Strokes involving sensory pathways can result in contralesional pain syndromes often refractory to pharmacologic interventions. Scrambler therapy (ST) is a noninvasive electroanalgesia device used to treat pain caused by peripheral neuropathy; however, data are scarce regarding its use in conditions secondary to central nervous system pathology. We evaluate the efficacy of ST to treat poststroke pain.

Methods: Twenty patients with a history of prior stroke resulting in contralesional pain were randomized to receive ST or Sham as an adjunct to their stable medication regimen. Participants underwent 5 consecutive daily 40-min sessions. The study was blinded to patient and assessor. Pain scores (0-10) were recorded at baseline, pre- and postsession, and 4 weeks after final treatment. Student's t-tests compared differences in the mean change in pain score between groups immediately post-treatment #5, and at 4-weeks. The chi-squared analysis compared the proportion of patients in each group with >50% pain reduction.

Results: Participants randomized to ST had a mean change in pain score of -3.73 (SD 2.85) postintervention and -2.57 (SD 2.07) at 4 weeks, while the Sham group had a mean change in score of -0.94 (SD 1.36) and -0.25 (SD 0.84) (p between groups = 0.012, 0.004, respectively). Significantly more participants treated with ST reported a >50% reduction in pain immediately postintervention compared to Sham (70% vs. 10%, p = 0.006), but not at follow-up (30% vs. 10%, p = ns).

Interpretation: ST may effectively decrease poststroke pain compared to Sham. Larger studies are needed to evaluate confounders such as stroke location, time from stroke, and concomitant treatment with medications.