Introduction 

Pain is defined as a subjective experience leading to a localised sensation and an unpleasant feeling. It can be caused by physical or psychological factors, which can result from injury, inflammation, or nerve damage. Pain involves specific receptors, known as nociceptors, which respond to damaging stimuli and transmit signals through nerves to the spinal cord and brain. Pain receptors in the body can be triggered by things like pressure, heat, and certain chemicals. Scientists have a good understanding of how these receptors detect and send pain signals, though the exact reasons for all types of pain can be different.¹

Treating pain involves the following drugs:

1. Opioid analgesics: They are pain relievers that contain opioids and are used to treat severe pain.
2. Non-opioid analgesics: They are pain relievers that do not contain opioids and are used to treat mild pain.
3. Adjuvant analgesics: They are drugs that can help with pain management. They include certain antidepressants, anticonvulsants, and muscle relaxants.
4. Corticosteroids: They are anti-inflammatory medications that can help reduce pain and swelling.

However, pain management strategies can have limitations, such as side effects from medications, including dizziness, bleeding, and weight gain. Current research aims to reduce these side effects, and one promising approach is the use of virtual reality (VR), which is the focus of this article.²

How is pain perceived?

Pain signals travel from the body's outer areas to the brain through special nerve cells. These nerve cells have their main parts in clusters near the spine and send out branches to both the body's outer areas and the spinal cord. The nerves that carry pain signals are usually thin and work slowly. These signals then move to the brain, including areas like the cortex, which helps us feel and understand pain. 

Chronic pain, typically defined as pain lasting more than three months, usually involves central sensitisation to varying degrees i.e., the nervous system becomes more sensitive to pain signals, making even mild discomfort feel much worse. 

Chronic pain can result from a combination of nociceptive (actual damage to body tissues), neuropathic (damage to nerves), and central mechanisms (changes in the brain and spinal cord). Hence, chronic pain is a complex sensory and emotional experience influenced by the individual's psychological state like emotions, thoughts, and mental health. Cognitive and emotional factors such as stress or anxiety can critically influence pain perception due to the connection between brain regions that control pain, attention, and emotions.

Role of genetics in pain perception

Genetic factors also play a role in pain sensitivity and chronic pain conditions, with an imperfect overlap between pain-related genes and chronic pain. For example, the adrenergic pathway involving the COMT gene (encodes catechol O-methyltransferase), which affects how our bodies break down certain chemicals, has been linked to chronic musculoskeletal pain. Variations in this gene, such as the Val158Met polymorphism, can change enzyme activity and influence a person’s risk of developing pain. ⁶

Other genetic variations, like those in the β2-adrenergic receptor gene (ADRB2) and serotonin pathway genes (HTR2A and SLC6A4), are associated with chronic pain conditions such as fibromyalgia. These genetic differences can lead to issues like poor regulation of the nervous system, altered pain perception, sleep issues, and anxiety all of which are common in people with chronic pain. ⁶

Understanding AI and VR technologies in healthcare 

There are several common Artificial Intelligence (AI) technologies used in healthcare, including Machine Learning (ML) and Neural Networks (NN), which are often integrated into virtual reality (VR) systems. Machine learning, a type of AI, has the ability to learn from its data through computer systems. ML algorithms are trained to find patterns in data sets. By using historical data, they can generate predictions for future trends. Current popular machine learning models used in our everyday lives include ChatGPT. 

On the other hand, neural networks are another type of AI. NN facilitates machine learning by analysing training examples, often pre-labelled, to identify patterns. Modelled after the human brain, they are made up of connected units, called nodes, arranged in layers, with information moving in one direction. Each node processes the information it receives and decides whether to pass it along based on certain criteria. During training, these criteria are modified until the network can reliably produce consistent outputs i.e., accurate results.³

Within the healthcare sector, neural networks are often used to examine cost reduction for patients with chronic diseases and make informed decisions at microlevels due to overlapping ethical issues. Whereas machine learning is used for diagnostic assistance, as tools for risk evaluation, and in applications for patient monitoring, which improve the physician's decision-making ability.⁴

Virtual reality (VR) is a computer-based 3D simulation or environment that users can interact with in a realistic manner using specialised electronic devices, such as headsets with screens or sensor-equipped gloves. In the healthcare industry, VR has shown great promise. Research shows its effectiveness in areas such as helping orthopaedic residents understand fracture anatomy, improving clinical skills in the Intensive Care Unit (ICU), and supplementing education for medical residents.⁵

AI-powered VR for pain management 

Thankfully, with ongoing research, the use of VR to treat chronic pain is promising. Research shows that VR has demonstrated effectiveness in alleviating pain and distress among patients undergoing various medical procedures such as burn wound care, chemotherapy, dental procedures, venipuncture, and extended hospital stays.⁹

Research also suggests that VR may not only alter the perception of pain stimuli but also impact how the brain physically processes pain. Notably, a study indicated that despite receiving therapeutic doses of opioids, 86% of burn injury patients undergoing wound care reported severe to extreme pain. Moreover, in another pilot study, the long-term effects of VR therapy on fibromyalgia were examined. Six women underwent 10 VR therapy sessions, with evaluations before treatment, after treatment, and six months later. The findings revealed a notable reduction in depression and improved coping strategies.⁷ Furthermore, research using VR for non-invasive mirror visual feedback alongside ketamine for one fibromyalgia patient showed a significant pain reduction over 15 trials, suggesting VR can effectively complement other pain treatments.⁸

Ultimately, putting on a VR headset immerses you in virtual environments, overwhelming your brain with new signals that compete with pain for attention. The brain's limited capacity to process inputs means VR effectively saturates your senses, leaving less capacity to focus on pain.

Benefits and challenges of VR in pain management

Benefits

• Reduced pain: VR creates immersive experiences that shift focus away from pain, thereby diminishing the perception of discomfort during medical procedures or episodes of chronic pain.
• Improved mental health: VR allows controlled exposure to anxiety-inducing situations, helping individuals confront and manage fears like phobias or PTSD in a safe environment.
• No side effects from taking drugs: VR provides a non-pharmacological option for managing pain, potentially decreasing reliance on conventional pain medications and their accompanying side effects.

Limitations

• Technical difficulties: VR systems may require technical expertise, making implementation and maintenance costly and complex. 
• Side effects and discomfort: Prolonged VR use can lead to side effects such as motion sickness and discomfort. 
• Accessibility: VR technology may not be readily available or affordable for all healthcare settings and patients, limiting its widespread adoption as a pain management tool. 

Summary

Pain is a complex experience influenced by both physical and psychological factors. Traditional treatments often involve medications with side effects. VR offers a new approach as it does not rely on drugs. VR, a computer simulation, is increasingly used in medical education and therapy to enhance skills and patient outcomes. 

Chronic pain involves central sensitisation and genetic factors affecting pain sensitivity. VR therapies have proven effective in alleviating pain and distress during medical procedures, suggesting they could be a valuable treatment option.  VR provides non-pharmacological pain relief by diverting attention from pain stimuli. It has shown success in reducing pain during medical procedures and chronic episodes, potentially reducing dependence on traditional pain medications. 

Implementing VR in healthcare faces challenges such as technical complexity, possible side effects like motion sickness, and limited accessibility due to cost. Despite these hurdles, VR offers promising benefits for pain management without the drawbacks of conventional treatments.