Effectiveness Not Established

Diathermy and Interferential Therapy

for Peripheral Neuropathy

Diathermy is a therapy using high frequency electric current to stimulate heat generation in tissue. Interferential therapy involves the use of two different frequencies of alternating currents, creating an electric field in a painful area with electrodes placed on the skin. This is aimed at improving blood circulation and relieving pain through the inhibition of pain signals in small diameter nerve fibers according to the gate control theory.

Research Evidence Summaries

Lindblad, K., Bergkvist, L., & Johansson, A.C. (2016). Evaluation of the treatment of chronic chemotherapy-induced peripheral neuropathy using long-wave diathermy and interferential currents: A randomized controlled trial. Supportive Care in Cancer, 24, 2523–2531. 

Study Purpose

To evaluate the effects of interferential therapy and long-wave diathermy at high power (ITH) compared to long-wave diathermy at low power (LDL) on peripheral neuropathy (PN) pain, sensory, and motor symptoms among adults with chronic chemotherapy-induced peripheral neuropathy (CIPN) symptoms in the lower extremities who completed chemotherapy treatment for various cancers

Intervention Characteristics/Basic Study Process

Intervention: Interferential therapy and ITH once per week for 12 weeks. A physical therapist delivered 15 minutes of interferential therapy (Electro Stimulation Device ES 520 and Vacuum Unit) to the lower legs for 15 minutes using four wet sponge–containing vacuum electrodes placed on the medial and lateral sides of the upper and lower portions of the lower leg. The stimulation intensity (0–100 Hz) was adjusted based on when the patient felt a strong but not painful stimulation. Long-wave diathermy (Skanlab 25 Body Wave® apparatus) was delivered at an unspecified high power for six minutes using an electrode and gel lightly applied in circular motions to the sole of the foot. A ground electrode was placed on the middle of the calf.
 
Sham control: LDL once per week for 12 weeks. A physical therapist delivered long-wave diathermy at an unspecified allegedly sub-therapeutic power level in the same manner as for the ITH group (Skanlab 25 Body Wave® apparatus electrode applied to the sole of the foot for six minutes).
 
Timepoints of measurement: Baseline (before randomization and ITH/LDL initiation), 12 weeks (immediately after ITH/LDL treatment completion), and 37 weeks after baseline

Sample Characteristics

  • N = 67   
  • AGE = 64 years (SD = 10.57 years)
  • MALES: 49.3%, FEMALES: 50.7%
  • CURRENT TREATMENT: Other
  • KEY DISEASE CHARACTERISTICS: The medical record charted numbness, tingling, pain, or swelling sensation in the feet/lower legs, and physicians diagnosed chronic CIPN related to platinum-, taxane-, or vinca alkaloid–based chemotherapy completed a mean of 11.49 months (SD = 10.67 months) prior to the study; varied tumor types
  • OTHER KEY SAMPLE CHARACTERISTICS: Participants were excluded if they had type 1 diabetes mellitus, PN related to other nonchemotherapy causes, or ongoing treatment with neurotoxic chemotherapy.

Setting

  • SITE: Single site   
  • SETTING TYPE: Not specified    
  • LOCATION: Sweden

Phase of Care and Clinical Applications

  • PHASE OF CARE: Late effects and survivorship
  • APPLICATIONS: Elder care, palliative care

Study Design

Three-group, sham-controlled, randomized, controlled trial

Measurement Instruments/Methods

Primary outcome: Numeric Rating Scale (NRS) of pain intensity ranging from 0 (no pain) to 100 (worst possible pain)
 
Secondary outcomes: NRS of discomfort (“uncomfortable feeling of not knowing where the feet are in relation to the room” [p. 2,526]) of 0 (no discomfort) to 100 (worst possible discomfort); zones of paresthesia (i.e., the number of zones with sensations of pins and needles, tingling, paresthesia, and numbness sensations [ranging from 0–10] indicated on a lower extremity body map and averaged between the bilateral extremities); Dizziness Handicap Inventory to measure subjective balance (scored 0–60); Tightened Romberg Test with closed eyes in tandem stance (bilateral leg average, best of three attempts, 0–60 seconds); One Leg Stance Test with closed eyes (bilateral leg average, best of three attempts, 0–30 seconds)

Results

There were no significant between-group differences at the 12-week and 37-week follow-ups in all outcomes: self-reported pain, discomfort, paresthesia/numbness, or balance, or in objectively measured balance. At the 12- and 37-week follow-ups, both groups reported significantly improved CIPN discomfort (p < 0.05), zones of paresthesia (p < 0.003), and subjective balance (p ≤ 0.025). Only the LDL group experienced improved pain at 12 weeks (p = 0.017), but neither group had significant improvements in pain at 37 weeks. Only the intervention group demonstrated significantly improved balance at 12 and 37 weeks, based on the objective measures (p ≤ 0.04).

Conclusions

This randomized, controlled trial provides no evidence to support the efficacy of interferential therapy and ITH compared to LDL once per week for 12 weeks for pain, CIPN discomfort, patient-reported balance, and objectively measured balance among participants with physician-diagnosed chronic CIPN.

Limitations

  • Small sample (< 100)
  • Baseline sample/group differences of import
  • Risk of bias (no blinding)
  • Risk of bias (sample characteristics)
  • Unintended interventions or applicable interventions not described that would influence results
  • Measurement validity/reliability questionable
  • Findings not generalizable
  • Questionable protocol fidelity
  • Subject withdrawals ≥ 10%
  • Convenience sampling used in this study increases the risk of sampling bias and decreases the generalizability of the results.
  • The definition of chronic CIPN was not defined, and participants had completed neurotoxic chemotherapy aa mean of 11.49 months (SD = 10.67 months) prior to the study, meaning some participants may have had unstable CIPN that naturally improved over time (i.e., maturation effects were likely responsible for the outcome improvements).
  • The primary outcome was pain, but about one-third of the patients had no pain at baseline. 
  • No measurement or control for key potential influencing factors of CIPN and pain (e.g., concomitant analgesic or psychotropic medication changes during the study; smoking; comorbidities, such as type 2 diabetes, peripheral arterial disease, alcohol dependence, vitamin B deficiency)
  • None of the measurements had sufficient validity and reliability. The NRS has not been validated as a measure of CIPN pain or discomfort, and the authors created the map of paresthesia zones but had not tested it psychometrically. No evidence was provided to support the validity and reliability of the balance measures for patients with CIPN.
  • There was 25.4% attrition by the 37-week follow-up, and no report of how missing values were handled (despite stating that an intent-to-treat analysis was conducted) was provided.

 

Nursing Implications

No evidence supports the efficacy of interferential therapy and long-wave diathermy, and, currently, this intervention should not be recommended to patients with heterogeneous types of painful and nonpainful CIPN. However, evidence shows that CIPN symptoms and balance may recover for some patients by one year after completing treatment with neurotoxic chemotherapy. Additional studies of nursing interventions for CIPN are needed.

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