Pediatric Amplified Musculoskeletal Pain Syndrome (AMPS): Treatment with Photobiomodulation

Low level laser therapy, or photobiomodulation, of the star ganglion may be an effective non-pharmacological, non-invasive treatment for enhanced musculoskeletal pain syndrome.

This article is part of a series on the use of light therapy for pain relief. See related pieces on Fibromyalgia, Migraine and Trigeminal Neuralgia.

Most first and second line painkillers aim to reduce the formation of PGE2 or reduce the transmission of pain in the hind horn via presynaptic or postsynaptic inhibition. However, there is growing evidence that other factors can lead to chronic pain syndromes, including an autonomic nervous system (ANS) imbalance.

The ANS balances the sympathetic and parasympathetic nervous systems. The sympathetic nervous system (SNS) is designed to prepare the body for “fight or flight,” while the parasympathetic nervous system (PNS) has the opposite effect, essentially maintaining homeostasis. ANS controls three physiological processes associated with chronic musculoskeletal (MSK) disease or chronic pain syndromes: 1-3

muscle blood flow muscle contractility sensory motor control

The working theory suggests that central sensitization resulting in over-activation of the SNS causes whole-body vasoconstriction, decreased blood flow to the muscles, muscle activation (spasms), and hyperalgesia and allodynia. There is also a decrease in parasympathetic activity, which would normally return the body to homeostasis. In addition, the imbalance in SNS and PNS activity can affect other systems, including cardiac, respiratory and gastrointestinal. This change in ANS has been associated with several chronic pain syndromes, including: 4

Amplified Musculoskeletal Pain Syndrome (AMPS)

AMPS is a term used to describe a continuum of diffuse or limited chronic non-inflammatory pain syndromes in children. Subsets of AMPS include CRPS, FMS, and widespread pain that does not fit diagnostic criteria for a specific syndrome.

Sherry et al. Reported that 80% of patients aged 12 to 16 years (509 women, 127 men) with AMPS between 2015 and 2019 are female, 79% white, 91% non-Hispanic.5,6 In addition, only 35 % of study Participants met the American College of Rheumatology (ACR) diagnostic criteria for fibromyalgia .5,7 There is a psychological component associated with AMPS in many patients, including anxiety (45%) and depression (27%) . The presence of psychological co-factors may be related to the type of pain (limited or diffuse) and the duration of the symptoms.5,6,8 External factors that can influence pain levels include high socioeconomic status, controlling parents and academically high-achieving children .6,9

The etiology of AMPS is unknown, but it is theorized that there is central sensitization leading to overactivation of the SNS, similar to chronic pain syndromes in adults.

Treating AMPS

Treatment for AMPS became more medicalized between 2008 and 2014, including an increase in the average number of drugs used, therapies tested, and caregivers observed. Without a significant change in pain score or duration. Pharmacological approaches alone have been found to be unsuccessful in the treatment of AMPS

Current treatments are thus aimed at restoring functional movement through intensive training or “resetting” the nerves by means of electrical stimulation at the sensory level. Sherry et al. Also reported a 90% success rate using high-intensity therapy, consisting of a combination of physical, occupational, and aquatic therapies, along with desensitization of the affected areas, as needed.9

The treatment program includes 6 to 8 hours of exercise per day for 2 to 3 weeks. This regimen is followed by high-intensity home exercise programs. Treatment is often accompanied by psychological interventions, if necessary. However, patients may not be able to complete the program due to the intense pain triggering. More recently, Calmare electrotherapy treatment has shown some success in the treatment of AMPS.11 However, this therapy is currently only available in specialist clinics.

Another possible approach to treatment is to reduce the activity of the sympathetic nervous system. The SNS uses chain ganglions, all of which are connected and run parallel to the spine. The three cervical chain ganglions are connected to the cardiac and pulmonary plexus, affecting the heart, lungs and blood vessel circumference.

The star ganglion (SG) is the center of the three cervical ganglions and is a common site for nerve blocks. SG blocks have been used to treat CRPS, FMS pain, herpes zoster infection affecting the head, neck, arm, or chest, 12 and PTSD. 13 An SG block consists mainly of analgesic medications, but photobiomodulation whether light therapy has proven successful. used to block the SG to relieve pain and cause a sympatholytic response

We propose to treat SG with PBM to inhibit the overactive sympathetic nervous system that is said to cause AMPS. PBM is biphasic and either stimulant (low dose) or inhibitory (high dose) .15 A high dose of PBM to the SG should produce a sympatholytic response, reducing the symptoms caused by the overactive SNS.

Case Report: Using SG Block to Reduce AMPS Symptoms

Case presentation

Patient is a 13 year old male. The patient has a history of knee fracture that has fully recovered to within normal limits and ADLs. The patient played in a trampoline park and developed the following symptoms: tachycardia, shortness of breath, dizziness, migraine, nausea, general weakness, dark vision, low blood pressure, profuse sweating, syncope, inability to stand or walk, severe global pain and report a have ‘out-of-body experience’. The patient was treated in an emergency room twice. However, the following diagnostic tests could not determine the cause of the symptoms: MRI, CT scan, X-rays, EKG and EEGs. The patient was told to rest, stay hydrated, exercise tolerance, and eat well. However, the patient continued to have symptoms.

Case Treatment

Based on the wide range of symptoms associated with the ANS, it was determined that the patient may be suffering from AMPS. PBM treatment was given using a 25 W emitter with super pulses laser (905 nm), infrared (875 nm) and red (660 nm) diodes. The SG is a deep structure, so to ensure that there were enough photons on the target for inhibition, PBM was applied bi-laterally for 10 minutes (see Figure 1 example) at a dose of 60 J per side. The prescribed course consisted of 12 treatments over 4 weeks.

Figure 1. Photobiomodulation treatment of stellate ganglion. The topic depicted is not the case presented.

The patient reported a positive response to treatment after the first session and the symptoms were completely resolved after the fourth session. PBM treatments were slowly discontinued to monitor the patient’s response and prevent a possible relapse. PBM was reduced to 1 treatment per week for 6 weeks without relapse of symptoms. Treatments were then reduced to 1 treatment every 2 weeks for 2 months, again with no recurrence of symptoms.

The patient is currently receiving 1 PBMT per month due to parental concerns about recurring symptoms. The patient’s mother reported that the patient has been symptom-free for 14 months and can fully participate in all activities of daily living, including football and playing in the trampoline park.

Case Discussion

Based on the case presented, low-level laser therapy or photobiomodulation of the stellate ganglion may be an effective non-pharmacological and non-invasive treatment for pediatric patients with AMPS. It is possible that PPE treatments for the SG may also be effective for the treatment of adult chronic pain syndromes associated with an overactive SNS. More research needs to be done to determine the appropriate treatment frequency for specific cases.

Conclusion

In the case presented, it is unclear whether the patient’s symptoms would have returned if we had discontinued low laser light therapy after the fourth treatment when all symptoms had resolved, or how often the patient may need maintenance treatment. Therefore, a double-blind RCT should be performed to determine the efficacy of this treatment and the best treatment protocol. Ideally, the study will include a comparison of the high-intensity exercise protocol, PBMT to the star ganglion, and a combination of PBMT and exercise. There is evidence supporting a synergistic effect of PBMT and exercise for the treatment of fibromyalgia syndrome in adults

Last updated: May 5, 2021

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