Evaluation of the treatment of chronic chemotherapy-induced peripheral neuropathy using long-wave diathermy and interferential currents: a randomized controlled trial

The purpose was to investigate the effects of long-wave diathermy in combination with interferential currents (interferential therapy and long-wave diathermy at high power (ITH)) in comparison with long-wave diathermy at a power below the active treatment dose (long-wave diathermy at low power (LDL), control group) on sensory and motor symptoms in patients with chronic chemotherapy-induced peripheral neuropathy (CIPN) in the lower extremities.

Sixty-seven patients with chronic CIPN were randomized to 12 weeks of either ITH or LDL. Follow-up assessments were performed after the treatment period and at 37 weeks after randomization. The primary outcome was pain (Numeric Rating Scale (NRS)), and the secondary outcomes were discomfort, nerve symptoms, subjective measurement of dizziness (Dizziness Handicap Inventory), and balance. Differences within and between groups were analyzed.

Pain intensity decreased significantly only in the LDL group directly after the treatment period from NRS median 25 to median 12.5 (P = 0.017). At the 37-week follow-up, no changes were detected, irrespective of group (NRS 13 vs. 20, P = 0.885). Discomfort decreased significantly in both groups at both 12 and 37 weeks after the baseline (P < 0.05). Balance disability showed significant declines in both groups at 12 and 37 weeks (P = 0.001/0.025 in the ITH group vs P = 0.001/<0.001 in the LDL group). Balance ability (tightened Romberg test) increased significantly at both 12 and 37 weeks in both groups (P = 0.004/<0.040 in the ITH group) but did not improve in the LDL group at any of the follow-up time points (P = 0.203 vs P = 0.383). The one-legged stance test was unchanged in the ITH group after 12 weeks but improved 37 weeks after baseline (P = 0.03). No significant changes were observed in the LDL group at any of the follow-up time points.

This study provides no support for the use of a combination of long-wave diathermy and ITH as a treatment option for patients with chronic CIPN. However, the chronic CIPN symptoms decreased with time irrespective of the treatment.