Twenty-three studies (n=1,321) were included in the review. There was insufficient information to determine the different study types.
Thirteen studies scored between 50% and 75% on the validity scale and two scored between 75% and 85%.
Five of the 6 trials of laser therapies showed a statistically significant difference between treatment and placebo groups following treatment on measures including pain, BDI, cervical range of motion, NHP, and on the neck pain and disability scale (p-values ranged from p<0.05 to p<0.001). In 2 trials there continued to be a statistically significant difference between treatment and placebo groups at the 3-month follow-up.
One low-quality study found transcutaneous electrical nerve stimulation (TENS) was equal to electrical muscle stimulation in reducing pain at follow-up, although superior immediately following treatment (p<0.01). Other trials found TENS to be effective but had final outcome measures immediately following treatment.
Two of the 4 studies assessing ultrasound found no significant effect on pain. One study reported a significant benefit of ultrasound, but the study was of a low quality. One study comparing high-power pain threshold ultrasound (HPPT-US) with conventional ultrasound reported a significant benefit of HPPT-US. However, this study also had a low validity score.
Three studies examined the use of magnet therapies. Two studies used repetitive magnetic stimulation and both found it to be superior to placebo on pain measures (p-values ranged from 0.022 to 0.001). One study reported that magnets placed on MTrPs on the abdomen for chronic pelvic pain were superior to placebo on measures of pain (p<0.05).
Four studies assessed as being of a higher quality examined various forms of physical or manual therapy. All suggested that therapies including Thai massage, Swedish massage, self applied ischaemic compression, massage and exercise, and transverse friction massage may offer benefits, but long-term follow-up was lacking.