Effects of Combining Music Therapy, Light Therapy, and Chromotherapy in the Treatment of Chronic Pain Patients: A Pilot Study

Background It is currently considered that around 30% of chronic pain patients are totally refractory to medical treatment. Among patients who remain responsive to medical treatment, it is estimated that between 20% and 50% are likely to discontinue treatment due to severe side effects. Given these therapeutic difficulties, a significant number of patients turn to complementary therapies. Objective The LineQuartz® is a medical device that combines 3 complementary therapies, namely, music therapy, light therapy, and chromotherapy. We propose to evaluate its effectiveness in chronic pain patients. Methods Between October 2021 and October 2022, 44 patients aged between 23 and 85 years (mean: 55.4 years) were included in a prospective study. All patients had background pain intensity greater than 4/10 on the Numerical Pain Scale (NS). Treatment consisted of 4 half-hour sessions, divided into one session per week for 3 weeks (21 days). Patients were assessed by the Brief Pain Inventory (BPI) and the Hospital Anxiety and Depression scale (HAD) the day before starting treatment (Day 0) and the day after the end of treatment (Day 22). Results Apart from the BPI item, “relationship with others,” all items improved significantly (p < 0.050). Background pain intensity (NS) and frequency of painful attacks improved very significantly (p < 0.001). The HAD anxiety subscore was also significantly improved (p < 0.001). Discussion. This open pilot study supports the idea that LineQuartz® has a place among complementary therapies dedicated to the treatment of chronic pain. However, these results need to be confirmed by a controlled study.


Introduction
Chronic pain is common, afecting over 30% of the French population [1].It mainly concerns neuropathic pain, spinal pain, or difuse pain.It is difcult to treat, rapidly afects quality of life, leads to a signifcant number of work stoppages, and is a priority in public health policy [2,3].
Level 1 and 2 analgesics are recommended as 1st and 2 nd line treatments but often prove inefective.Level 3 analgesics, mainly morphine, also often fail, and it is currently considered that around 30% of chronic pain patients are totally refractory to medical treatment [4].Among patients who remain responsive to treatment, it is estimated that between 20% and 50% are likely to discontinue treatment due to severe side efects such as drowsiness, mood disorders, or cognitive impairment [5].Given these therapeutic difculties, a signifcant number of patients turn to alternative therapies [6] represented by complementary therapies [7,8].
Tese diferent therapies contribute to a global approach to pain, in association with the multimodal approach (including psychological, social, and professional care) and therapies aimed at treating the pain itself (analgesic drugs and/or central and peripheral nervous system stimulation techniques).Tey share the following certain common features [9]: (i) Tey work in harmony with the body's self-healing mechanisms.(ii) Tey are "holistic," i.e., they treat the whole person.(iii) Tey encourage patients to take an active part in the process.(iv) Tey focus on well-being and disease prevention.
Te LineQuartz ® is a medical device that combines 3 complementary therapies, namely, music therapy, light therapy, and chromotherapy.
Music therapy, especially in its receptive form, is recognized as being able to modify pain sensation [12][13][14].Light therapy acts on the body clock and circadian rhythm.It has been shown to act on sleep disorders [15] and mood disorders [16,17].Chromotherapy uses colors to modulate or produce physiological efects.Te most studied efect is on anxiety and stress, often encountered in chronic pain patients [18].
Te aim of this article is to evaluate the efcacy of LineQuartz ® in the treatment of chronic pain patients.Tis is a pilot study which will serve to lay the foundations for a controlled trial.

Inclusion Criteria.
Te inclusion criteria included the following: patients aged at least 18 years, chronic pain evolving for at least 3 months, and pain not soothed by level 1 and 2 analgesics and intensity assessed as at least 4/10 on the Numerical Pain Scale (NS).

Exclusion Criteria.
Te exclusion criteria included the following: patient unable to be properly assessed (dementia and psychosis), patient refusing to sign the information and informed consent document, withdrawal of consent, appearance of acute pain during the study period, chronic conditions likely to interfere with the efectiveness of the planned measures (visual or hearing problems), and introduction during the study of other analgesic therapeutic strategies (e.g., acupuncture), which may interfere with the results.

Study Design.
Te study was an open pilot study, with a case series design, carried out in 44 patients included between October 2021 and October 2022.
All patients signed an informed consent form.Te protocol has been approved by the Nantes Hospital Ethics Committee (GNEDS (Groupe Nantais d' Éthique dans le Domaine de la Santé)), with the reference 23-101-08-280.
(1) Numerical Pain Scale (NS): the patient rated his or her background pain intensity with a number between 0 (no pain) and 10 (maximum imaginable pain).For overall assessment of the procedure (at D0 and D22), we used the average pain level recorded over the last 24 hours (item 5 of the Brief Pain Inventory (BPI) pain assessment) [22].To assess the efectiveness of the 4 therapeutic sessions, we used the NS value recorded just before and just after the session (BPI item 6).
It is accepted that the cutof point between mild and moderate pain (afecting activities of daily living) is 4/10 on the Numerical Pain Scale [23].In many therapeutic trials, patients presenting with pain ≤4/ 10 are excluded from the study, as they do not present pain judged to be sufciently intense [24].For these reasons, we chose to include only patients with pain ≥4/10.(2) Number of painful attacks per day (if any).
(3) Brief Pain Inventory interference items [22]: a numerical scale ranging from 0 to 10 was used to assess several items generally afected by chronic pain.Te total score is the sum of the 2 scores, which can range from 0 to 42. (5) Each patient was asked at D22 whether they had been satisfed with the treatment and whether they would recommend it to someone else sufering from chronic pain.
Prior to treatment, the DN4 questionnaire [26] was analyzed to assess the importance of the neuropathic component of the pain.
Medical analgesic treatment was recorded in the patient's fle at D0 and D22 for an evaluation using the Medication Quantifcation Scale (MQS version 1992) [27,28].Each drug has a score that depends on the potential severity of side efects (detriment) (e.g., score of 2 for nonsteroidal anti-infammatory drugs and score of 6 for strong opioid derivatives) and daily doses (subtherapeutic � 1, minimal therapeutic � 2, maximal � 3 and supratherapeutic � 4).For example, a patient with an MQS score between 2 and 4 is on "weak" treatment and above 6 as on "strong" treatment.
Many potential candidates for inclusion in this protocol lived far from the therapists.It was deemed difcult to get them all to return for an evaluation that would be desirable 15-30 days after the end of treatment.For this pilot study, we only scheduled a fnal assessment the day after the end of treatment (D22).
2.4.Terapeutic Procedure.Te device has 7 telescopic tubes that can be oriented above the person to be treated (Figure 2).Each of the 4 sessions has a specifc objective.During the session, the patient lies supine, covered by a white sheet (Figure 2).Headphones are placed over the ears.1st session: the aim is to provide the body with precise luminous and vibratory information through the diffusion of electromagnetic light waves (less than 90 lumens) combined with the difusion of musical vibrations set at a frequency of 432 Hz.Tis type of session should induce frequency homeostasis (see discussion).Other sessions difer in the choice of themes used in music therapy.2nd session: the aim is to act on 2 components involved in biorhythms (emotional and intellectual) by broadcasting musical works by 2 composers.(1) A romantic work by Schubert, with the aim of stimulating the emotional cortical and subcortical areas known to be activated when listening to music.(2) A work by Bach, with the aim of stimulating the more analytical areas of listening to well-known pieces.Session 3: listening to a well-known work by Mozart, with the aim of stimulating cortical areas linked to memory, proprioception, and spatial perception.Session 4: sacred music by composer Michel Pepe promotes relaxation and pain reduction by distending time and space.

Statistical Analysis.
Te diference between the main variables recorded before and after treatment was assessed by analysis of variance (ANOVA) and the nonparametric Mann-Whitney test.
Efect size was assessed using Jacob Cohen's d-index [29].A value of 0.2 corresponds to a weak efect, 0.5 to a medium efect, 0.8 to a strong efect, and 1.3 to a very strong efect.
Nineteen patients were not taking any medication for pain relief.Tirteen had treatment considered "weak," with an MQS score between 2 and 4 (mean: 3 ± 0.5 (standard deviation)).We combined these 2 groups into a single group (group 1) with a mean MQS score of 1.2 ± 1.5.Twelve patients had treatment considered as "strong" (group 2), with an MQS score between 6 and 18 (mean: 10.6 ± 3.8).Tere was a signifcant diference in the MQS score between group 1 and group 2 (p < 0.001).
Patients in group 1 had a mean pretreatment NS score of 5.7 ± 1.4 and those in group 2 a score of 6.5 ± 0.9.Te diference was marginally signifcant (p � 0.042).
Te NS score of patients in group 1 improved on average by 52.6% (±27.4) and that of patients in group 2 by 39.8% (±29.9).Te diference was not signifcant (p � 0.396).
Tere was no change in analgesic treatment between D0 and D22 (see discussion).
Te results (Table 1), assessed at D22 (end of treatment), show a signifcant improvement (p < 0.050) in the following variables (in order of signifcance (p) and efect size (d)): Most patients (38/44 (86.4%)) were satisfed with the treatment, and 88.6% of them (39/44) would recommend the same treatment to someone with the same chronic pain.
No side efects have been reported.Each therapy session brought an improvement in the NS (on average, 1.8 point/10), which was signifcant for the frst 3 sessions (Table 2).In the days following the session, the NS worsened by an average of 1.2 point per week.Looking ahead, it could be estimated that after a treatment of just 4 therapeutic sessions, patients can lose an average of 3.6 points (1.2 × 3) 3 weeks after stopping treatment, bringing patients' pain levels back to their initial level (2.8 + 3.6 � 6.4).
If we consider the number of signifcantly improved items, spinal pain (n � 10) comes top with the following 5 improved items: background pain, number of painful attacks, general activity, normal work, and anxiety.In 2 nd position comes widespread pain (n � 12) with the following 4 improved items: background pain, number of painful attacks, sleep, and anxiety.Rheumatic pain (n � 11) comes in 3 rd with only the following 3 items improved: background pain, number of painful attacks, and general activity (Table 3).
Te length of time the pain had been present before treatment seems to infuence the outcome.When pain duration was relatively short (between 6 months and 2 years), there was a signifcant improvement in the following 7 items: background pain, number of painful attacks, general activity, mood, normal work, sleep, and anxiety.When pain lasted between 2 and 8 years, the improvement concerned the following 6 items: background pain, number of painful attacks, general activity, enjoyment of life, anxiety, and depression.When the pain lasted for many years (between 8 and 50 years), the improvement concerned only the following 4 items: background pain, number of painful attacks, general activity, and walking ability (Table 4).
Analysis of the DN4 questionnaire enabled us to identify 27 patients with a score ≥4 and therefore presenting a predominant or exclusively neuropathic component or pain.Tese were widespread pain (n � 10), joint pain (rheumatic  Evidence-Based Complementary and Alternative Medicine  .IS: change recorded between the end of one session and just before the next.After one week, the sessions lose their efectiveness, with an average loss of 1.2 point on the NS.

Discussion
Tis study suggests that LineQuartz ® can improve chronic pain patients in almost all BPI-assessed symptoms.Te most improved symptoms were background pain and the number of painful attacks.Continuous background pain is more common in widespread pain.Painful attacks are often "mechanical," triggered by movement or posture, and are more often found in spinal pain.Perhaps, this is why these 2 pathologies seemed to respond best to treatment.
It should be noted that the treatment proved highly efective, above all, in the areas where we might expect it to be, given the supposed mechanisms of action of the therapies implemented, i.e., pain (music therapy), sleep (light therapy), mood (light therapy), and stress (chromotherapy).However, the treatment also proved efective in areas that suggest an improvement in "motor and/or motivational" abilities, such as improving general activity and work capacity.
It is likely that the follow-up was too short (22 days) to allow proper assessment of depression, enjoyment of life,  Only scores that improved signifcantly (p < 0.050) are shown.When pain lasted less than 2 years, the improvement concerned 7 items.Te improvement was highly signifcant for background pain, number of painful attacks, general activity, and sleep. 6 Evidence-Based Complementary and Alternative Medicine and relationships with other items and observing a change in medical analgesic treatment.Given the potential duration of the treatment efect (around 3 weeks), assessment should also be carried out at D37, D43, and D52.Te relatively modest efect size for these 3 items (between 0.41 and 0.54) suggests that a study involving a larger number of cases might have yielded a more signifcant result.Te efect of music therapy on pain is widely appreciated.In a study of cancer patients, it was shown that a receptive music therapy session lasting 20-25 minutes provided an average improvement of 58% on the visual analog pain scale and that this efect lasted about 30 minutes after the end of the session [31].However, patients questioned on the contribution of music therapy highlighted the following 4 items that did not directly concern pain relief: (1) forgetting one's illness, total disconnection, (2) relaxation, comfort in relation to care, (3) fnding oneself again, opening to the psyche, directing one's fear or emotions, and transforming them, and (4) good mood, positive thinking, dynamism, and morale.Te authors have thus considered music therapy to be a form of supportive care.In an analysis of the value of music therapy in oncology, music therapy was considered most useful for improving patients' moods [32], while complementary therapies likely to improve pain were represented more by massage therapy, relaxation techniques, and acupuncture [7].However, the direct efect of music therapy on pain intensity has been demonstrated.In a controlled study of cancer patients, after a 30-minute session of receptive music therapy, patients in the treatment group (n � 62) improved signifcantly in pain intensity (p < 0.001) compared with a control group (n � 64) [33].Te mechanism of action of music therapy was investigated by analyzing the changes induced in functional imaging by listening to diferent types of musical pieces.In functional MRI, signifcant activation of the nucleus accumbens (NAc) and ventral tegmental area (VTA) was found [34].Tese structures are part of the limbic system and contain dopaminergic neuronal circuits involved in pain modulation and reward phenomena [35].Pain modulation would involve connections between the NAc, the prefrontal cortex, and noradrenergic neural circuits involving neurons in the locus coeruleus (LC) [36].Activity in the prefrontal cortex is thought to depend in part on interactions between dopaminergic and noradrenergic neurons [36,37].Te prefrontal cortex is itself connected to the anterior cingulate cortex, insula, amygdala, and hippocampus, which are structures involved in modulating the afective component of pain [38].Te role of NAc in modulating neuropathic pain and its ability to prevent a transition to chronicity has been demonstrated experimentally [39].Perhaps, this is why Line-Quartz ® has proved particularly efective on neuropathic pain and pain that has been evolving for less than 2 years.Te action of music therapy on dopaminergic circuits that modulate prefrontal cortex activity could be enhanced by also acting on noradrenergic circuits that also modulate prefrontal cortex activity, as can-do occipital nerve stimulation (ON) by tDCS (transcranial direct current electrical stimulation) [40].Another mechanism for the action of music therapy involves the characteristics of sound, in particular its diferent vibratory frequencies [41].Normally, in a state of homeostasis, the electromagnetic felds emanating from the body and its various organs and tissues have a certain vibratory frequency.If this frequency changes in a certain area of the body, that area will no longer be in resonance with the frequencies of the other parts of the body and may malfunction.Certain frequencies, such as 432 Hz, are supposed to re-establish an adequate resonance frequency.Tis can be called frequency homeostasis.
Light therapy essentially acts on circadian rhythms via melatonin secretion by the epiphysis, infuenced by the light/ dark cycle [42,43].It is easy to see how light therapy could improve sleep disorders and seasonal depression, a priori linked to a relative lack of light in winter [44].Improving sleep disorders and mood are the main actions of light Evidence-Based Complementary and Alternative Medicine therapy [45].It can thus indirectly improve the quality of life of chronic pain patients.However, the visual or light signal picked up by the retina is transmitted to the epiphysis via a noradrenergic pathway that passes through the brainstem before reaching the superior cervical ganglion and then the epiphysis [42].Light stimulation of noradrenergic pathways passing through the brainstem [45] could potentiate the efect of music therapy, which also indirectly depends on noradrenergic pathways linking the LC to the prefrontal cortex [32].Tis potentiating efect could possibly explain why LineQuartz ® could have a greater efect than music therapy alone.In LineQuartz ® , chromotherapy is not specifcally aimed at treating pain, but is placed in a more global context of repairing an energetic imbalance that may be caused by stress.Tis imbalance may have consequences for the functioning of neural circuits involved in pain [46].Chromotherapy generates diferent types of waves, notably electromagnetic, which are supposed to act on the hormonal system but also at cellular level, helping to maintain an energetic balance that promotes harmonious functioning of the organism.Tis principle is like that of REAC (Radio Electric Asymmetric Conveyer) technology [47,48], which uses a burst stimulation current (250 ms and 5.8 GHz) applied to the auricle or to a specifc area to be treated.Te objective efcacy of this technique is refected in an improvement in maladaptive motor behavior, which is thought to be the result of repeated stress episodes encountered throughout life.Tis behavior is assessed by the "functional dysmetria assessment."Very interesting results, concerning physical activity and motor behavior have been obtained in patients with neurodegenerative diseases [49,50].It is perhaps this same mechanism that explains the improvement in general activity and work capacity found in our patients.
Te main limitations of this study are the absence of a control group.Te results of this study should, therefore, be considered as preliminary and should be confrmed by a controlled study including an arm without LineQuartz treatment.Te lack of follow-up is also a limitation of this study.A future study should include a follow-up of at least 1 month after the end of treatment.Te recruitment of patients by therapists rather than primary care providers may introduce bias into the sample.In the next study, patients will be recruited from two pain centers in Nantes.

Conclusion
Tis study supports the idea that LineQuartz ® has a place among complementary therapies dedicated to the treatment of chronic pain.Te data from this study encourage further clinical investigation into the use of LineQuartz in the treatment of chronic pain patients.Music therapy's mechanism of action at the level of dopaminergic circuits that modulate prefrontal cortex activity could be enhanced by tDCS stimulation of occipital nerves (tDCS-ON) [36].A controlled study including a control arm, an arm treated only with LineQuartz ® , and an arm including a tDCS-ON session performed at the same time as LineQuartz ® treatment would be very interesting.Tis protocol should include an evaluation performed at least 1 month after the end of treatment and include an assessment of functional dysmetria.Te best candidates for inclusion in this protocol should be patients sufering from neuropathic pain for less than 2 years.
work (e) Relationships with others (f ) Sleep (g) Enjoyment of life (4) Hospital Anxiety and Depression scale (HAD) [25]: anxiety and depression were assessed separately by 7 questions, resulting in a score ranging from 0 to 21. 2 Evidence-Based Complementary and Alternative Medicine

( 3 )Figure 1 :
Figure 1: Protocol schedule.Te BPI (Brief Pain Inventory) and the HAD (Hospital Anxiety and Depression scale) were assessed before the start (D0) and after the end (D22) of the therapeutic protocol.Te protocol consisted of 4 therapeutic sessions (S1-S4), each lasting 30 minutes and spaced 7 days apart (D1-D7, D7-D14, and D14-D21).Te Numeric Pain Rating Scale (NS) was collected just before and just after each session.

Figure 2 :
Figure2: Te LineQuartz ® light and color therapy system.CE-certifed lamps comply with European standards for medical devices that emit neither ultraviolet nor infrared light.

4
Te ends of the 7 telescopic tubes are ftted with height and side adjustable tubes.Each tube is ftted with a specifc quartz crystal oriented on the patient's vertical axis, approximately 30 centimeters from his or her body.Each tube has a specifc color flter, in line with the principle of chromotherapy.Te device was patented in December 2013 by engineer Mr Yannick Delgado and built by Societé DYCOM SAS (Saint Herblain 44800 France).It was recognized as a medical device (under European Directive 93/ 42/EEC according to Annex IX relating to medical devices.Article II Classifcation: Class I DM noninvasive device) on January 15, 2016.

Table 1 :
Evolution of BPI and HAD scores collected before (D0) and after treatment (D22) (see BPI item details in text).Apart from the "relationships with others" item, all other BPI items and the 2 HAD items improved signifcantly (p < 0.050).Te efect size was very large on background pain (d � 1.7) and number of painful attacks per day (d � 1.7) items.* : Numerical scale corresponding to average pain over the last 24 hours (BPI item 5).SD: standard deviation.n/day: number of painful attacks per day.

Table 2 :
Evolution of pain intensity (numerical pain scale ranging from 0 to 10) before and after each therapeutic session.
* * Numerical Pain Scale (NS) recorded just before and just after each session (S)

Table 3 :
Evolution of BPI and HAD scores between D0 and D22 on according to the type of pathology responsible for the pain.

Table 3 :
Continued.In patients with chronic spinal pain, 5 items improved, with 4 of them showing a signifcant efect size (between 1.0 and 2.2).

Table 4 :
Evolution of BPI and HAD scores between D0 and D22 according to duration of pain evolution.

Table 5 :
Evolution of BPI and HAD scores between D0 and D22 according to the presence or absence of neuropathic pain.Only scores that improved signifcantly (p < 0.050) are shown.Tese results suggest that treatment is more efective in the neuropathic pain group, with 8 items statistically signifcantly improved (p < 0.050), including the following 5 highly signifcantly (p < 0.003): background pain, number of painful attacks, general activity, sleep, and anxiety.