It is estimated that US$100 billion per year are lost to pain related healthcare expenditures and lack of productivity due to pain. Clearly, this is a problem which must be addressed through finding more effective and cheaper solutions to pain control. One of the most common approaches to pain in a clinical setting, is the multimodal analgesic approach, a strategy with the primary goals of: enhanced pain relief, reduced side effects and minimised opioid use. It combines multiple techniques / medications to provide pain relief. The rough outline of the analgesic ladder goes as follows:
slight pain → paracetamol
mild pain → paracetamol + NSAID
moderate pain → paracetamol + NSAID + codeine
severe pain → paracetamol + NSAID + morphine
As can be seen, through combining different pharmaceuticals, the approach aims to alleviate pain in the most effective way, whilst minimising risk of development of addictions, or other unwanted side effects. The multimodal analgesic approach also combines other methods, such as massage and music to achieve this aim, which carry much fewer side effects than many pharmaceuticals; for instance, non-steroidal anti-inflammatory drugs (NSAIDs) often cause gastric irritation, whilst opioids, as well as being addictive, can cause nausea and respiratory depression.
In a study carried out on veterans between 21 and 88 years, a group of 23 participants were played music whilst undergoing radiofrequency lesioning (RFL), whilst a group of 21 participants underwent the procedure without music. RFL is a painful procedure which lasts between 30 and 60 minutes, where electrical pulses are administered through a needle in the facet joint, to block nerves for pain relief. It is useful in controlling the pain from nerve conditions such as degenerative disc disease and stellate ganglions. Pain and anxiety are common throughout the procedure, and a visual analog scale (VAS) was used to measure the pain and anxiety levels of the participants before and after the procedure. 87% of participants in the music group claimed that listening to music was helpful, and this was also seen in a 2 point reduction in self reported pain or anxiety in this group compared to the no music group. Although this study reveals the potential for music in pain treatment, it does not reveal the underlying mechanism by which music achieves this effect. The study also brings to light the need for clarification on a certain point: in the study, anxiety and pain are measured simultaneously, and treated in much the same way. Although they may seem to be separate concepts, one psychological and one physiological, linking the two is extremely common, especially following Melzack and Wall’s proposal. Ronald Melzack and Patrick Wall put forward the gate control theory of pain in 1965, where they suggested that the perception of pain is determined not only by the activation of nociceptors (pain receptors) but also by other neural mechanisms in the spinal cord and brain. This would include pain catastrophizing and anxiety. Pain catastrophizing can be defined as a collection of amplified and pessimistic cognitive and emotional patterns in response to real or expected painful experiences. The Pain Catastrophizing Scale (PCS) considers three factors: magnification, rumination and helplessness. The effect of music on this specific aspect of pain was addressed in a randomised controlled trial carried out in Singapore, on two groups of 55 women undergoing cesarean delivery. One group listened to music in the preoperative and intraoperative period, whilst the other group acted as a control. The utility of music for this particular procedure, in the place of pharmaceuticals is due to the fact that concerns have been raised over fetal / breastmilk transfer of drugs. Although there was no significant difference in the scores for acute pain between the two groups, music listening was significantly associated with lower visual analog scale-anxiety (VAS-A) scores, PCS scores, rumination, magnification and helplessness scores separately. Given placebo effects account for up to 50% of the effectiveness of pain treatments, there is certainly a place for music in reducing the psychological aspect of experiencing pain.
One mechanism by which it has been proposed that music affects the physiological pain response is through the autonomic nervous system (ANS). The ANS is a neural network responsible for maintaining homeostasis within the body. It is composed of the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The SNS sources energy from the metabolic output for ‘fight or flight’ actions, whilst the PNS works to restore, or ‘rest and digest’, through promoting anabolic activities. SNS activation is linked to a higher heart rate and blood pressure, whilst the opposite occurs with PNS activation. The SNS becoming predominant over the PNS is thus associated with higher rates of depression, heart failure and hypertension. When pain is perceived, the SNS is activated, leading to physiological responses associated with a ‘fight or flight’ response, characterised by an increased heart rate, dilation of pupils, release of adrenaline and cortisol (hormones associated with stress and which enhance alertness), and sweating. If the patient feels anxiety or fear as part of the pain response, these emotions will also activate the SNS, magnifying the pain perception. Music is considered to be a stimulus which promotes PNS dominance, with sedative music leading to greater PNS activity than excitative music. Along this line, crescendos and increases in tempo are linked to higher SNS activity. Interestingly, tempo appears to be the overriding stimuli, overcoming other parameters such as pitch and rhythm - so music which has high pitches and a lively rhythm, if played at a slow tempo, will still promote PNS dominance, dulling pain perception and relaxing the body. In particular, it has been found that people tend to show a preference for tempi that are 1, 1.5 and 2 times their resting heart rate, highlighting the fact that this is not solely a psychological, but a physiological mechanism.
Music certainly has a role in clinical settings, serving as a cheap, effective, non-addictive option to other pain medication. Its efficacy can be improved with more research to enable greater specificity in the variables which can be altered, such as rhythm, pitch, dynamics and tempo. Although the extent to which music can serve to alleviate pain is still unclear, the $17.8 billion spent annually in the United States on prescription medications for pain is most likely an unnecessarily large figure, and one which can be reduced through a more multimodal approach.
Bibliography:
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https://www.annualreviews.org/doi/10.1146/annurev-pharmtox-010818-021542