A comparative study of the dose-dependent effects of low level and high intensity photobiomodulation (laser) therapy on pain and electrophysiological parameters in patients with carpal tunnel syndrome

Eur J Phys Rehabil Med. 2020 Dec;56(6):733-740. doi: 10.23736/S1973-9087.19.05835-0. Epub 2019 Nov 18.


Background: Carpal tunnel syndrome (CTS) is a common peripheral nerve disorder of the wrist. Nonsurgical treatments e.g. laser therapy may cause potential beneficial effects.

Aim: To compare the dose dependent effects of low level laser therapy (LLLT) and high intensity laser therapy (HILT) on pain and electrophysiology studies in patients with CTS.

Design: Double-blind randomized controlled trial.

Setting: Outpatient physiotherapy clinic.

Population: Ninety-eight participants with CTS, aged between 20 to 60 years, were randomly assigned to five groups.

Methods: All participants undertook four standard exercises, with one group serving as exercise-only controls. Patients were randomly allocated to either high or low fluence LLLT or high or low fluence HILT received over 5 sessions. All patients were assessed by visual analogue scale, median compound muscle action potential (CMAP) and sensory nerve conduction studies before and 3 weeks after the interventions.

Results: VAS was significantly lower in all groups after 3 weeks (P<0.05). CMAP latency decreased in all groups. The interaction of group and time (5×2) was significant for pain (P<0.001), the latency of CMAP (P=0.001) and CMAP amplitude (P=0.02). The interaction of group and time was not significant for the CMAP conduction velocity, sensory nerve latency and amplitude (P>0.05).

Conclusions: HILT with a power of 1.6 W and low fluence of 8 J/cm2 was superior in reduction of pain and improvement of the median motor nerve electrophysiological studies compared to LLLT and exercise-only control groups.

Clinical rehabilitation impact: LLLT and HILT in conjunction with exercise program are effective in reducing pain and improving median motor nerve conduction studies of the patients with CTS. It seems that high power and low fluence laser therapy is better than LLLT and exercise interventions to treat these patients.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Carpal Tunnel Syndrome / physiopathology*
  • Carpal Tunnel Syndrome / therapy*
  • Combined Modality Therapy
  • Double-Blind Method
  • Exercise Therapy*
  • Female
  • Humans
  • Laser Therapy / methods*
  • Male
  • Middle Aged
  • Neural Conduction / physiology*
  • Pain Measurement
  • Young Adult