Effect of Pulsed High-Intensity Laser Therapy on Pain,Adhesions,and Quality of Life in Women Having Endometriosis: A Randomized Controlled Trial

Abstract

Objective: The purpose of this study was to assess the effectiveness of pulsed high-intensity laser therapy on pain, adhesions, and quality of life in women with endometriosis. Background data: Endometriosis is among the most common gynecological problems affecting females of childbearing age. The majority of women with endometriosis seek treatment to alleviate pain. Materials and methods: The sample included 40 women with endometriosis to either a mild or a moderate degree aged between 24 and 32 years. They were randomly assigned to two groups, group I of 20 women received pulsed high-intensity laser therapy three times per week for 8 weeks, as well as the usual regimen of hormonal treatment given to endometriosis patients, and group II of 20 women were given sham laser treatment three times per week for 8 weeks and the usual regimen of hormonal treatment. For all patients, pain, the degree of endometriosis, and quality of life were measured using present pain intensity and pain relief scales, laparoscopy, and the Endometriosis Health Profile (EHP-5) before treatment began and at the end of the 8 weeks. Results: In comparison to the sham laser treatment, pulsed high-intensity laser therapy produced a significantly different result (p < 0.0001), in women with endometriosis. Conclusions: Pulsed high-intensity laser therapy is an effective method of pain alleviation, reducing adhesions, and improving the quality of life in women with endometriosis.

Introduction

Endometriosis is among the most common gynecological problems affecting females of childbearing age. It occurs regardless of race or ethnicity and is marked by the growth of ectopic endometrial tissue,¹ which occurs when the endometrium that normally lines the inside of the uterus grows outside it. The tissue responds to the menstrual cycle in the same way as if it had remained in the uterus,² building up, breaking apart, and bleeding at each cycle. Unlike normal menstruation, however, the blood cannot be discharged, resulting in inflammation and swelling of the tissue, possibly producing scar tissue together with pain and adhesions, as well as infertility.^3,4

There is no correlation between the degree of severity of the illness and how severe the symptoms are, as more severe symptoms can occur in relatively mild cases of endometriosis.⁵ Mostly, the pain is localized in the lower abdomen and deep pelvis. It is often described as a dull, aching pain, which patients in severe cases may suffer throughout their cycle.⁶ A relationship between infertility and endometriosis is known to exist. The path of the egg to the uterus may be completely blocked by scarring, but fertility can be impaired even in milder cases.⁷ Approximately, one quarter of women who had a laparoscopy due to pelvic pain were diagnosed with endometriosis, while it present in 20%, of infertile women, and it fell to 4.1% in women who had received tubal legation.^6,8 Currently, laparoscopy is the only effective means of diagnosing endometriosis to determine the degree of adhesions, which are rated as minimal, mild, moderate, and severe^9,10 by the American Society for Reproductive Medicine.

Endometriosis is present in about 10% of women of reproductive age, with the incidence increasing in middle-aged women.¹¹ The spectrum of possible symptoms is wide and may include dysmenorrhea, dyspareunia, chronic pelvic pain, and pain related to ovulation, varying with the form and locus of endometrial foci.^12
–14 It can result in fatigue, infertility, abnormal bleeding from the uterus, and problems with the bladder and bowel. It also has negative effects on quality of life, impacting on social life, and work as well as on reproduction and ability to have a family.^15,16 Additional symptoms which may develop include allergies, fibromyalgia, asthma, eczema, autoimmune inflammatory disease, chronic fatigue syndrome, and hypothyroidism,¹⁷ as well as in women diagnosed with the disease after the age of 40, an increased risk of breast cancer due to prolonged exposure to raised levels of endogenous aestrogen.¹⁸

Treatment goals for endometriosis include pain alleviation, preserving fertility and minimizing adhesions. The most common reason for a woman to seek treatment is pain alleviation.¹⁹ However, the ideal medical treatment remains to be developed. All treatments presently available have side effects, and there is no medical therapy effective in improving fertility.^20,21 Retrospective findings show poor long-term symptom reduction from the medical and surgical treatments commonly available, and each is associated with numerous side effects.²² Medical treatment mimics physiological states; when treatment ends, the symptoms often reoccur; often as early as 6 months after the end of treatment.²³ As medical therapies and surgery require repeated follow-up and have side effects, it is common for patients to resort to low-cost methods that are both nonmedical and nonaggressive.²⁴

Pulsed high-intensity laser therapy (HILT) penetrates deeply into the tissue, causing chemical and mechanical changes as well as inducing thermal mechanisms.²⁵ HILT fields have physical properties that may be responsible for observed profibrinolytic effects, including mechanical and thermal effects. HILT is quick to reduce inflammation and painful symptoms.²⁶ It uses a specific waveform, in which regular amplitude peaks and shot time produce photochemical and photothermic effects in the deep tissues, resulting in increases in blood flow, vascular permeability, cell metabolism, and the tissue's photomechanical level, attaining very fast application times.²⁷ Therefore, this study aims to determine the effectiveness of pulsed HILT on pain, adhesions, and quality of life in women with endometriosis.

Materials and Methods

Subjects

Forty women from hospitals in Makkah who suffered severe pelvic pain and had been diagnosed by laparoscopy as suffering from mild or moderate endometriosis, as defined by the revised classification of endometriosis of the American Society of Reproductive Medicine, participated in this study. The patients were between 24 and 32 years of age, with a body mass index not greater than 29 kg/m². They were also free from diabetes, impaired sensation, gynecological hemorrhage, and tubo-ovarian abscesses. All participants signed informed consent forms agreeing to participate and to the publication of the results of the study. All participants received the usual regimen of hormonal treatment for endometriosis (100 mg medroxyprogesterone acetate every 2 weeks for 1 month, then once monthly). No physical therapies were given while the study was in progress. The research committee of the Physical Therapy Department, Faculty of Applied Medical Sciences in Umm Al-Qura University, Makkah, Saudi Arabia approved the study.

Randomization

Patients were randomly assigned into two groups, group I (HILT group) and group II (control group), using a simple random sample technique. Group I patients received pulsed HILT three times per week for 8 weeks, while those in group II received sham laser at the same frequency for the same time period. Before the intervention, one assessor (a physician) blinded to the study outcome evaluated the clinical assessment parameters, while another assessor (a physician) evaluated the outcome measures after the intervention. Both assessors were not aware of the prescription of interventions, the primary investigator was aware of the intervention and implemented it to the patients, so that the patients and the assessors were blinded, while the therapist was not.

Laser protocol

Group I participants HILT via a pulsed Nd:YAG laser from a HIRO 3 device (ASA, Vicenza, Italy). The apparatus used postulates (Nd:YAG), with pulsed emission (1064 nm), a peak power of 3 kW, energy density fluency from 810 to 1780 mJ/cm², a 120–150 μs pulse duration, and a duty cycle of 0.1%, with a frequency of 10–40 Hz. The total average energy of the HILT application was 1300 J administered in three phases, with the patient lying supine in a comfortable and relaxed position supported by small cushions under their knees, back, and neck accommodating body curvature. In the first phase, laser fluency was 510 mJ/cm² for an average total energy of 500 J, including fast scanning for the suprapubic area and the left and right iliac fossa. The intermediate phase was applied using a headpiece to 15 points, of which 5 were in the suprapubic area and 10 were over the iliac fossa region on each side with 20 J, a fluency of 610 mJ/cm², and 14 sec at each point, with a total applied energy applied of 300 J. The last phase was identical to the first phase, except that scanning was slower and the total application time was ∼20 min. Table 1 shows all parameters of HILT that were applied in this study.

Table 1.

Parameters of High-Intensity Laser Therapy

Parameters	Value
Pulsed emission	1064 nm
Peak powers	3 kW
Energy density	810–1780 mJ/cm²
Pulse duration	120–150 μs
Frequency	10–40 Hz
Laser fluency (phase 1)	510 mJ/cm²
Laser fluency (phase 2)	610 mJ/cm²
Laser fluency (phase 3)	510 mJ/cm²
Average total energy	1300 J
Time	20 min
Point of treatment	15 points (contact)

Outcome measures

Participants were quizzed on the severity of pain using present pain intensity (PPi),²⁸ a graphic rating scale in which numerical values are at equal distances along a line where 0 represents no pain, 1 is mild pain, 2 is moderate pain, 3 is severe pain, and 4 describes an unbearable level of pain. For both groups, this was performed before and after the course of treatment. The pain relief (PR) scale²⁸ was also used after the course of treatment to indicate how much PR had been experienced. PR operates in a way similar to PPi, in that, 0 represents no relief, 1 is slight relief, 2 is good relief, 3 is excellent relief, and 4 describes complete relief.

Laparoscopy was performed by a gynecologist to determine the degree of endometriosis in accordance with the American Society for Reproductive Medicine score¹⁰ for all patients in both groups, before the course of treatment began and at its end. Quality of life was evaluated using the Endometriosis Health Profile (EHP-5),²⁹ a valid instrument for that purpose. It contains 11 markers, 5 indicate difficulty in walking, lack of control or being powerless, mood swings, lack of social support, and self-image all from the core questionnaire. The other six are taken from the modular questionnaire and may not be applicable to every woman suffering from endometriosis. They include difficulties with work, difficulties with intercourse, worries about infertility, worries about treatment, relationships with children, and relationships with medical professionals. Each item is ranked using a five-point scale, with never = 0, rarely = 1, sometimes = 2, often = 3, and always = 4. There is also the option to mark an indicator as not relevant.³⁰

Data analysis

Data analysis was performed using IBM SPSS version 19.0 (IBM Corp, Armonk, NY). Frequencies and improvement percentages were also reported. In addition, mean, standard deviation (SD), and mean difference (MD) were also reported. The Wilcoxon test was performed for two related samples and the Mann–Whitney test for two independent samples. The results were considered statistically significant when p < 0.05.

Results

Pain severity

PPi scale

As shown in Table 2, before the course of treatment began, most HILT group members felt severe pain or unbearable pain (90%). This was significantly (p < 0.001) reduced after treatment, with the majority of participants reporting no or mild pain (85%). In the control group, the results before beginning treatment were very close to those in the HILT group. After treatment was completed, many participants complained of moderate or severe pain (75%).

Table 2.

The Present Pain Intensity Score Before and After Treatment in Both Groups

	Group I (HILT)				Group II (control)
	Before Tx		After Tx		Before Tx		After Tx
	N	%	N	%	N	%	N	%
No pain	0	0.00	8	40.00	0	0.00	2	10.00
Mild pain	0	0.00	9	45.00	0	0.00	3	15.00
Moderate pain	2	10.00	3	15.00	2	10.00	6	30.00
Severe pain	10	50.00	0	0.00	9	45.00	9	45.00
Unbearable	8	40.00	0	0.00	9	45.00	0	0.00
Mean	3.30		0.75		3.35		2.10
Standard deviation	0.66		0.72		0.67		1.02
Mean difference	2.55				1.25
Improvement%	77.27%				37.31%
Z	3.818
p	0.0001

Significant p < 0.05.

HILT, high-intensity laser therapy; N, number of patients; Tx, treatment.

Present relief scale

Many participants (85%) in the HILT group experienced complete or excellent relief after the treatment course as shown in Table 3, while in the control group, complete and excellent relief were only reported by four participants (20%). The posttreatment mean values of PR were significantly (p < 0.0001) different between the two groups.

Table 3.

The Degree of Pain Relief in Both Groups After Treatment

	Group I (HILT)		Group II (control)
	N	%	N	%
No relief	0	0.00	0	0.00
Slight relief	0	0.00	10	50.00
Good relief	3	15.00	6	30.00
Excellent relief	9	45.00	2	10.00
Complete relief	8	40.00	2	10.00
Mean	3.25		1.80
Standard deviation	0.72		1.01
Mean difference	2.24
Z	4.024
p	0.0001

Significant p < 0.05.

Degree of endometriosis as assessed by adhesion score

Before treatment, more than half of the HILT group suffered from moderate endometriosis (60%) as shown in Table 4, but all participants were found to have minimal or mild endometriosis, with no cases of moderate endometriosis, after treatment. In the control group, 65% of the cases suffered from moderate endometriosis before treatment, with nearly half of the cases (55%) found to have minimal endometriosis or mild endometriosis after treatment. In addition, the posttreatment mean adhesion scores were significantly (p < 0.0001) different between groups.

Table 4.

Degrees of Endometriosis Before and After Treatment in Both Groups

	Group I (HILT)				Group II (control)
	Before Tx		After Tx		Before Tx		After Tx
Degree of endometriosis	N	%	N	%	N	%	N	%
Minimal endometriosis	0	0.00	11	70.00	0	0.00	2	10.00
Mild endometriosis	8	40.00	9	30.00	7	35.00	9	45.00
Moderate endometriosis	12	60.00	0	0.00	13	65.00	9	45.00
Mean	2.60		1.45		2.65		2.35
Standard deviation	0.50		0.51		0.48		0.67
Mean difference	1.15				0.30
Improvement%	44.23%				11.32%
Z	3.907
p	0.0001

Significant p < 0.05.

Quality of life

Table 5 shows a comparison of the level of quality of life between the groups. After treatment, the HILT group had a better quality of life in comparison with the control group as evidenced by higher scores in all five domains of EHP-5 and a significant difference in the mean value of quality-of-life scores.

Table 5.

Mean Values of Health-Related Quality of Life in Both Groups After Treatment

	Group I (HILT)										Group II (control)
	Never		Rarely		Sometimes		Often		Always		Rarely		Never		Sometimes		Often		Always
	N	%	N	%	N	%	N	%	N	%	N	%	N	%	N	%	N	%	N	%
Difficult to walk because pain	8	40	10	50	2	10	0	0	0	0	2	10	1	5	2	10	15	75	0	0
Lack of control and powerlessness	7	35	10	50	3	15	0	0	0	0	0	0	1	5	1	5	18	90	0	0
Mood swing	8	40	8	40	4	20	0	0	0	0	0	0	1	5	1	5	18	90	0	0
Lack of social support	9	45	9	45	2	10	0	0	0	0	1	5	1	5	2	10	16	80	0	0
Lack of self-image	8	40	8	40	4	20	0	0	0	0	0	0	1	5	1	5	18	90	0	0
Mean	15.75										16.25
Standard deviation	3.73										3.60
Mean difference	0.50
Improvement%	73.00%
Z	5.427
p	0.0001

Significant p < 0.05.

Discussion

The purpose of this study was to determine the effectiveness of pulsed HILT in alleviating pain and reducing adhesions in women suffering from endometriosis. The study results showed that the HILT group experienced a statistically significant decrease in severity of pain and adhesions, with a highly statistically significant improvement in their quality of life (p < 0.0001). Numerous studies have found HILT to be more effective than low-level laser therapy (LLLT), which has been attributed to HILT's higher intensity and the greater depth reached by the laser.²⁶ It should also be noted that the laser's effectiveness relies on specific factors, including wavelength, locus, duration, dose, and target tissue depth. Earlier research suggests that the ability to penetrate human skin is dependent on wavelength,^31,32 but there have been no studies that investigated how HILT affected the treatment of women suffering from endometriosis.

HILT's sedative action may result from a number of mechanisms that involve its capacity to decrease conduction of pain impulses and to raise the rate of production of substances in human tissue that mimic the action of morphine.²⁶ It may also be able to block the transmission of pain through Aδ- and C-fiber, increasing blood flow, vascular permeability, and cell metabolism.³³ There is a paucity of literature on the use of HILT as an intervention compared with LILT, and a few studies have discussed HILT use in the management of several musculoskeletal disorders such as knee osteoarthritis,^34,35 low-back pain,^36,37 cervical spondylosis,³⁸ neck pain,³⁹ subacromial impingement syndrome (SAIS),⁴⁰ and osteoporosis.⁴¹ Although there is limited evidence about the effectiveness of HILT in diseases affecting, very few studies have been conducted. A recent randomized clinical trial investigated the efficacy of HILT versus pulsed electromagnetic field (PEMF) in the management of primary dysmenorrhea, finding that both interventions were effective, but HILT induced a more significant decrease in pain and prostaglandin levels than PEMF.⁴² In the current study, HILT also showed a significant improvement (p < 0.0001) compared with sham laser treatment in women with endometriosis in terms of PR, decreasing the adhesions and improving the quality of life. However, the current study provided a different comparison group from the above study and used a different laser protocol based on the type of patients, which may influence the generalization of the results.

This study's results are consistent with those of Kheshie et al.,³⁴ who found that HILT was more effective than LILT in the management of people with knee osteoarthritis. The authors concluded that HILT combined with exercise was more effective than LLLT with exercise on pain reduction and functional improvement. Furthermore, other studies have reported that HILT was more effective than some forms of physiotherapy modalities. According to Santamato et al.,⁴⁰ HILT was more effective than therapeutic ultrasound in treating patients with SAIS after 10 treatment sessions in the following outcomes: pain, shoulder movement, function, and muscle strength. However, this study did not include a control or a placebo group, had no follow-up period, and the intervention period was only 2 consecutive weeks which may limit the generalization of study results. Another study compared HILT and traction therapy with the Saunders device in the treatment of cervical spondylosis.³⁸ The results showed that both interventions demonstrated analgesic efficacy and had similar effect immediately after the treatment and after 4 weeks in pain and disability improvement, but after 12 weeks, HILT significantly maintained the beneficial therapeutic effects in comparison to traction.

The current study also supports the findings of Alayat et al.,³⁶ who investigated the effect of HILT in the management of chronic low-back pain. The authors concluded that HILT combined with exercise demonstrated a greater benefit to patients with chronic low back pain (CLBP) than HLLT alone or placebo laser with exercise with regard to the lumbar range of motion (ROM), pain, and disability. Moreover, HILT was significantly superior compared to placebo laser in the treatment of chronic neck pain in terms of cervical ROM, pain, and functional activity after 6 weeks of treatment.³⁹ However, both these studies included only male participants, which may limit their results only to a male population.

The present findings agree with Bjordal et al.,⁴³ who described laser treatment as effective for acute pain and bringing about short-term pain reduction by reducing inflammation. They also support the findings of Soliman et al.⁴⁴ that LLLT and reflexology could significantly improve ROM and reduce the severity of pain in diabetic patients with adhesive capsulitis. Therefore both therapies may be recommended to treat a frozen shoulder until more data have been obtained on their individual effectiveness. Furthermore, Teixeira et al.⁴⁵ reported that LLLT treatment prevents intra-abdominal adhesions with no compromise to the abdominal wall's strength or healing.

This study's results are also consistent with those of Hwang et al.,⁴⁶ who found that LLLT has the ability to significantly suppress an inflammatory (macrophage-conditioned medium induced) response in annulus fibrosus cells in a manner dependent on both time and wavelength. They concluded that LLLT has potential in anti-inflammatory therapy for patients suffering from painful disc degeneration. In addition, Jin et al.⁴⁷ reported that laser therapy was effective and safe in managing hypertrophic scars.

A meta-analysis reported that laser therapy has a positive effect on wound tensile strength, reducing the size, healing time, and total collagen content of wounds, resulting in an overall treatment effect size ≥2.22; this meta-analysis showed the largest average effect size to be derived from energy densities between 19 and 24 J/cm².⁴⁸ Another meta-analysis on the effect of laser therapy on tissue repair in clinical cases showed a positive effect described as small to moderate, with an overall mean effect size being +0.34 [95% confidence interval (CI) = −0.25 to 0.94].⁴⁹ All these findings support the hypothesis that suitable laser therapy is effective for both pain and function, and that a broad range of parameters are effective in laser therapy.

Conclusions

In conclusion, HILT is effective in treating and reducing endometriosis symptoms and in improving patients' quality of life. It is suitable for use as an alternative conservative therapy to current medications, which are associated with numerous side effects.

Footnotes

Acknowledgments

Many thanks to Dr. Sameh Baz who performed the laparoscopy diagnosis and referred the patients from gynecology departments of Makkah hospitals. We also take the opportunity to thank all patients who participated in this study.

Author Disclosure Statement

No competing financial interests exist.

References

Taylor

. Endometriosis—a missed malady. AORN J, 2003; 77:301–313.

Drews

, Barlik

, Łukaszewski

. Conservative treatment of endometriosis. Ginekol Pol, 2012; 83:209–213.

Mavrelos

, Saridogan

. Treatment of endometriosis in women desiring fertility. J Obstet Gynaecol India, 2015; 65:11–16.

Spremovic

, Jovan

, Snezana

, Nebojša

. Diagnostic and treatment of endometriosis—recommendations for clinical practice. Srp Arh Celok Lek, 2017; 145:89–94.

Hassa

, Tanir

, Urag

. Symptoms distribution among infertile and fertile endometriosis cases with different stages and localizations. Eur J Obstet Gynecol Reprod Biol, 2005; 119:82–86.

Slap

. Menstrual disorders in adolescence. Best Pract Res Clin Obstet Gynaecol, 2003; 17:75–92.

Prentice

. Endometriosis. BMJ, 2001; 323:93–95.

Spaczynski

, Duleba

. Diagnosis of endometriosis. Semin Reprod Med, 2003; 21:193–208.

Terri

, Roger

. Endometriosis and chronic pelvic pain. Nurs Womens Health, 2008; 12:382–395.

10.

American Society for Reproductive Medicine (ASRM). Revised classification of endometriosis. Fertil Steril, 1997; 67:819–821.

11.

Memarzadeh

, Muse

, Fox

. Differential diagnosis and treatment of endometriosis. Available at: http://www.health.am/gyneco/endometriosis (Last accessed July 23, 2017 ).

12.

DeCherney

, Nathan

. Current Obstetric and Gynecologic Diagnosis and Treatment, 9th ed. Philadelphia: Lange Medical Books/McGraw-Hill, 2003.

13.

Spirof

. In: Spirof Women Infertility of Clinical Endocrinology, 1st ed. Ghazi

Jahani B

(translator). Tehran: Golban Ghazi Jahani, 2005.

14.

Berk

, Novak

. In: Berk and Novak Gynecology, 1st ed. Ghazi

Jahani B

(translator). Tehran: Golban Ghazi Jahani, 2009.

15.

Farquhar

, Sutton

. The evidence for the management of endometriosis. Curr Opin Obstet Genecol, 1998; 10:321–332.

16.

Harkki-Siren

, Sjoberg

, Kurkit

. Major complication laparoscopy: a follow up Finnish study. Obstet Gynecol, 1999; 94:94–98.

17.

Sinaii

, Cleary

, Ballweg

, Nieman

, Stratton

. High rates of autoimmune and endocrine disorders, fibromyalgia, chronic fatigue syndrome and atopic diseases among women with endometriosis: a survey analysis. Hum Reprod, 2002; 17:2715–2724.

18.

Bertelsen

, Mellemkjaer

, Frederiksen

, et al. Risk for breast cancer among women with endometriosis. Int J Cancer, 2007; 120:1372–1375.

19.

Proctor

, Roberts

, Farquhar

. Combined oral contraceptive pill (OCP) as treatment of primary dysmenorrhoea. Cochrane Database Syst Rev, 2001; 4:CD002120.

20.

Hornstein

, Surrey

, Weisberg

, Casinol

. Leuprolide acetate depot and hormonal add-back in endometriosis: a 12 month study. Lupron add-back study group. Obstet Gynecol, 1998; 91:16–24.

21.

Moghissi

, Boyce

. Management of endometriosis with oral medroxy progesterone acetate. Obstet Gynecol, 2000; 47:265–267.

22.

Lemaire

. More than just menstrual cramps: symptoms and uncertainty among women with endometriosis. J Obstet Gynecol Neonatal Nurs, 2004; 33:71–79.

23.

Oliver

, Overton

. What the physiotherapist needs to know about endometriosis. J Assoc Chartered Physiotherapists Womens Health, 2014; 114:44–49.

24.

Mahboubeh

, Niloofar

, Parvin

, Reza

. The effects of massage therapy on dysmenorrhea caused by endometriosis. Iran J Nurs Midwifery Res, 2010; 15:167–171.

25.

Starkey

, Rebane

, Drobizhev

, et al. New two-photon activated photodynamic therapy sensitizers induce xenograft tumor regressions after near-IR laser treatment through the body of the host mouse. Clin Cancer Res, 2008; 14:6564–6573.

26.

Zati

, Valent

. Physical therapy: new technologies in rehabilitation medicine (translated to English). Edizioni Minerva Medica, 2006:162–185.

27.

Kujawa

, Zavodnik

, Buko

, Lapshyna

, Bryszewska

. Effect of low-intensity (3.75–25 J/cm2) near-infrared (810 nm) laser radiation on red blood cell ATPase activities andmembrane structure. J Clin Laser Med Surg, 2004; 22:111–117.

28.

Hartrick

, Kovan

, Shapiro

. The numeric rating scale for clinical pain measurement: a ratio measure?. Pain Pract, 2003; 3:310–316.

29.

Jones

, Jenkinson

, Kennedy

. Development of the short form endometriosis health profile questionnaire: the EHP-5. Qual Life Res, 2004; 13:695–704.

30.

Azita

, Maryam

, Fatemeh

, Ali

. The short form endometriosis health profile (EHP-5): translation and validation study of the Iranian version. J Ovarian Res, 2011; 4:11.

31.

Enwemeka

. Attenuation and penetration of visible 632.8 nm and invisible infrared 904 nm light in soft tissues. Laser Ther, 2001; 13:95–101.

32.

Nussbaum

, Van Zuylen

. Transmission of light through human skinfolds: effects of physical characteristics, irradiation wavelength, and skin-diode coupling relevant to phototherapy. Physiother Can, 2007; 59:194–207.

33.

Chow

, Armati

, Laakso

, Bjordal

, Baxter

. Inhibitory effects of laser irradiation on peripheral mammalian nerves and relevance to analgesic effects: a systematic review. Photomed Laser Surg, 2011; 29:365–381.

34.

Kheshie

, Alayat

, Ali

. High-intensity versus low-level laser therapy in the treatment of patients with knee osteoarthritis: a randomized controlled trial. Lasers Med Sci, 2014; 29:1371–1376.

35.

Angelova

, Ilieva

. Effectiveness of high intensity laser therapy for reduction of pain in knee osteoarthritis. Pain Res Manag, 2016; 2016:9163618.

36.

Alayat

, Atya

, Ali

, Shosha

. Long-term effect of high-intensity laser therapy in the treatment of patients with chronic low back pain: a randomized blinded placebo-controlled trial. Lasers Med Sci, 2014; 29:1065–1073.

37.

Fiore

, Panza

, Cassatella

, et al. Short-term effects of high-intensity laser therapy versus ultrasound therapy in the treatment of low back pain: a randomized controlled trial. Eur J Phys Rehabil Med, 2011; 47:367–373.

38.

Haładaj

, Pingot

, Topol

. The effectiveness of cervical spondylosis therapy with Saunders traction device and high-intensity laser therapy: a randomized controlled trial. Med Sci Monit, 2017; 23:335–342.

39.

Alayat

, Mohamed

, Helal

, Khaled

. Efficacy of high-intensity laser therapy in the treatment of chronic neck pain: a randomized double-blind placebo-control trial. Lasers Med Sci, 2016; 31:687–694.

40.

Santamato

, Solfrizzi

, Panza

, et al. Short-term effects of high-intensity laser therapy versus ultrasound therapy in the treatment of people with subacromial impingement syndrome: a randomized clinical trial. Phys Ther, 2009; 89:643–652.

41.

Alayat

MSM

, Abdel-Kafy

, Elsoudany

, Helal

, Alshehri

. Efficacy of high intensity laser therapy in the treatment of male with osteopenia or osteoporosis: a randomized placebo-controlled trial. J Phys Ther Sci, 2017; 29:1675–1679.

42.

Thabet

AAE

, Elsodany

, Battecha

, Alshehri

, Refaat

. High-intensity laser therapy versus pulsed electromagnetic field in the treatment of primary dysmenorrhea. J Phys Ther Sci, 2017; 29:1742–1748.

43.

Bjordal

, Johnson

, Iversen

, Aimbire

, Lopes-Martins

. Low-level laser therapy in acute pain: a systematic review of possible mechanisms of action and clinical effects in randomized placebo-controlled trials. Photomed Laser Surg, 2006; 24:158–168.

44.

Soliman

, Mahmoud

, Serry

, Dawood

. Therapeutic effects of low-level laser and reflexology on adhesive capsulitis in elderly type 2 diabetes patients. Asian J Pharm Clin Res, 2014; 7:317–321.

45.

Teixeira

, Vasconcellos

, Oliveira

, Petroianu

, Alberti

. Prevention of abdominal adhesions and healing skin after peritoniectomy using low level laser. Lasers Surg Med, 2015; 47:817–823.

46.

Hwang

, Shin

, Kim

, Yoo

, Jo

, Kim

. Low level light therapy modulates inflammatory mediators secreted by human annulus fibrosus cells during intervertebral disc degeneration in vitro. Photochem Photobiol, 2015; 91:403–410.

47.

Jin

, Huang

, Li

, et al. Laser therapy for prevention and treatment of pathologic excessive scars. Plast Reconstr Surg, 2013; 132:1747–1758.

48.

Woodruff

, Bounkeo

, Brannon

, et al. The efficacy of laser therapy in wound repair: a meta-analysis of the literature. Photomed Laser Surg, 2004; 22:241–247.

49.

Fulop

, Dhimmer

, Deluca

, et al. A meta-analysis of the efficacy of phototherapy in tissue repair. Photomed Laser Surg, 2009; 27:695–702.