Effectiveness Not Established

Topical Menthol

for Peripheral Neuropathy

Menthol is an organic compound made synthetically or obtained from mint oils. Topical creams containing menthol have been used for relief of minor pain and as a topical analgesic. Menthol appears to activate a channel involved in regulation of sensory neuropathic pain, and has been examined for its effects as a topical agent on painful chemotherapy-induced peripheral neuropathy.

Research Evidence Summaries

Fallon, M.T., Storey, D.J., Krishan, A., Weir, C.J., Mitchell, R., Fleetwood-Walker, S.M., . . . Colvin, L.A. (2015). Cancer treatment-related neuropathic pain: Proof of concept study with menthol—A TRPM8 agonist. Supportive Care in Cancer, 23, 2769–2777. 

Study Purpose

To evaluate whether a topical menthol product has clinical benefit for pain of peripheral neuropathy

Intervention Characteristics/Basic Study Process

Patients were given a 1% menthol in aqueous cream and were instructed how to apply it to the affected area and corresponding dermatome region of the spine twice daily. Patients were followed for four to six weeks.

Sample Characteristics

  • N = 40  
  • MEAN AGE = 61 years
  • AGE RANGE = 20–89 years
  • MALES: 37%, FEMALES: 63%
  • KEY DISEASE CHARACTERISTICS: Patients had chronic neuropathic pain: 80% had chemotherapy-induced peripheral neuropathy diagnosed by a physician, and 20% had scar pain related to treatment for breast cancer. Breast and colon cancers were the most common. 
  • OTHER KEY SAMPLE CHARACTERISTICS: Median of 11 months since chemotherapy treatment

Setting

  • SITE: Single site   
  • SETTING TYPE: Outpatient    
  • LOCATION: United Kingdom

Phase of Care and Clinical Applications

PHASE OF CARE: Late effects and survivorship

Study Design

Open-label

Measurement Instruments/Methods

  • Brief Pain Inventory-Short Form (BPI-SF)
  • Hospital Anxiety and Depression Scale (HADS)
  • Leeds Assessment of Neuropathic Symptoms and Signs (LANSS)
  • Walking ability: GAITRite mat to measure velocity and cadence
  • Hand dexterity
  • Quantitative sensory testing (QST)

Results

Eighty-two percent showed an improvement in pain scores (p < 0.001). Significant improvements were observed in some aspects of quantitative sensory testing for mechanical detection threshold, cool stimulus, and warm stimulus. Both walking velocity and cadence improved. No significant changes in hand dexterity or LANSS scores were reported.

Conclusions

The findings suggest that the topical application of menthol can improve symptoms of chronic chemotherapy-induced peripheral neuropathy.

Limitations

  • Small sample (< 100)
  • Risk of bias (no control group)
  • Risk of bias (no blinding)
  • Risk of bias (no random assignment)
  • Subject withdrawals ≥ 10%

Nursing Implications

This study is limited by its small sample size and study design, but shows promising proof of concept results related to molecular receptors in sensory nerves that appear to respond to topical menthol. Very few interventions have been shown to prevent or effectively treat chemotherapy-induced peripheral neuropathy, so further research on the use of topical menthol is warranted. Further well designed studies are needed.

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