Excimer Laser treatment to stop scratching ?

• The excimer laser is a 308nm device used in the treatment of localized lesions of psoriasis and vitiligo.

• In this study done on mice (“dry skin model”), atopic dermatitis (AD) was induced with application of “dermatphagoides farina body” ointment in shaved area twice a week for 3 weeks

• ANTIHYPERINNERVATION. Results after one excimer session show:
  • improvement in dermatitis score and reduced scratching bouts
  • in cultured dorsal root ganglion cells:
    • increased bleb formation in nerve fibers (which is a morphological marker of nerve degeneration)
    • decreased expression of nicotinamide mononucleotde adenyltransferase 2 (a neuronal survivor factor)

• ANTI DNA-DAMAGE. Then the authors used a cut off filter (COF):
  • which blocks below 297nm and thus decreases DNA damage (which is thus marked by reduced cyclobutane pyrimidine dimer (CPD) production).
  • Coupled to the previous results It enables measurement of the antihyperinnervative effect and the decreased DNA damage:
    • Result: Excimer laser + COF decreased CPD production in epidermal keratinocytes

Conclusion of the study: The excimer laser (308nm) induced epidermal nerve degeneration with reduced DNA damage (because of COF use)

Comment: medication is sometimes the last resort to treat itch and the drugs all have very limiting side effects. Before that excimer lasers can be tried if phototherapy has failed or if the itch is localized.

Contributors

Dr Christophe Hsu – dermatologist. Geneva, Switzerland

Source of information: p12-02 Kamo A et al. Irradiation by excimer lamp induces intraepidermal nerve degeneration and inhibits itch-related behavior in a dry-skin mouse model. JSID Annual Meeting (Japanese Society of Investigative Dermatology, 日本研究皮膚科学会) 2014 – Osaka, Japan