Separate physical and psychosocial causes of pain
Not all pain is the same. Depending on the cause, it requires different therapies. A team led by ETH Zurich has now developed a method that enables doctors to better differentiate between physical and psychosocial pain.
Severe pain often has physical causes. However, emotional, psychological and social factors can influence how we perceive and react to pain. "Pain is usually made up of a physical and a psychosocial component," explains Noemi Gozzi, a doctoral student at ETH Zurich.
Doctors try to take this into account as much as possible in their treatment recommendations. Until now, however, it has been difficult to clearly separate the two components. Doctors determine pain and its intensity using relatively simple approaches based on patients' subjective descriptions. This often leads to them prescribing non-specific therapies. Painkillers containing opioids are still frequently used, despite all the disadvantages: the undesirable side effects, the long-term diminishing effect and the risk of becoming addicted to the medication - or even dying due to an overdose.
Individual treatment
In recent years, Stanisa Raspopovic's group, of which Gozzi is a member, together with researchers from Balgrist University Hospital in Zurich, has developed an approach to clearly distinguish and quantify the physical and psychosocial components of pain. They publish their new method in the current issue of the journal Med. Raspopovic was until recently Professor of Neuroengineering at ETH Zurich.
"Our new approach should help to assess patients' pain on a more individual basis and thus enable more personalized treatment in the future," says Raspopovic. If the pain is primarily physical, doctors are likely to focus their treatment on the physical level, for example with medication or physiotherapy. If, on the other hand, psychosocial factors play a major role in the experience of pain, it may be advisable to positively change the perception of pain with psychological or psychotherapeutic support.
Large data set
To develop the new method, the researchers analyzed data from 118 volunteers - including people with chronic pain and healthy controls. The scientists asked the study participants detailed questions about their perception of pain and any psychosocial symptoms such as depression, anxiety and exhaustion, as well as how often they were in so much pain that they were unable to go to work. The researchers also recorded how well the participants were able to distract themselves from pain and how much pain made them brood, feel helpless and exaggerate the pain.
The researchers used standardized measurements of the sensations of spontaneous pain in order to compare the participants' perception of pain. The researchers treated the participants with small, harmless but painful heat pulses on the skin. In order to record the physical reaction to the pain, the researchers measured the brain activity of the study participants using an electroencephalogram (EEG) and the electrical conductivity of the skin. The latter is an indication of sweating and is used to measure stress, pain and emotional arousal. Finally, the study participants' diagnoses, which were compiled by researchers at Balgrist University Hospital, were incorporated into the extensive data set.
Machine learning for precision medicine
Machine learning helped the researchers to evaluate the large amount of data, clearly distinguish between the two pain components and develop a new index for each. The index for the physical component of pain indicates the extent to which the pain is caused by physical processes. The index for the psychosocial component indicates the extent to which emotional and psychological factors intensify the pain. Finally, the scientists validated these two factors using the extensive measurement data from the study participants.
The new method, with its combination of measuring body signals and self-reporting, its computer-assisted evaluation and the two indices as a result, is intended to support the doctors treating patients. "The method makes it possible to precisely characterize the pain condition of a particular person in order to better decide what kind of targeted treatment is needed," says Gozzi.
The researchers at ETH Zurich and Balgrist University Hospital are continuing this project together with the Suva-run Clinique romande de réadaptation in Sion and the spinal cord injury department of a hospital in Pietra Ligure, Italy: they are investigating the clinical relevance of the new method in a long-term study.
Source: ETH
