Pain is a sensory perception – just like people feel heat, cold or touch, they also perceive pain. Acute pain is an indication from the body that something is wrong at the moment.
If the pain becomes independent and lasts for a long time, it can lose its warning character and develop into an independent disease, chronic pain.
In the case of acute pain, the cause is usually clearly recognisable and can be treated specifically. The time limit from which pain is referred to as chronic is six months.
Pain does not always have a physical cause. Sometimes, in the course of mental illnesses (such as depression), pain sensations occur which are, however, more attributable to psychological factors. However, persistent pain can also lead to depression.
The International Association for the Study of Pain defines pain as “…an unpleasant sensory and emotional experience associated with, or described in terms of, actual or potential tissue damage”.
Typical forms of pain are:
Acute pain signals to the body that there is an acute danger, such as injury. In the case of acute pain, the cause is therefore usually clearly identifiable and can be treated specifically.
In contrast to acute pain, chronic pain takes on the form of its own clinical picture over time. The cause is usually no longer detectable or no longer present and can therefore no longer be treated. The nerves continuously send pain impulses to the brain, although there is no stimulus left. The nerve cells have developed a kind of pain memory. The time limit at which painful sensations are referred to as chronic pain is six months.
Neuropathic pain (nerve pain) occurs when nerve tissue is damaged, for example by diseases such as diabetes mellitus. Depending on the cause, this damage can affect the peripheral (distant) or the central nervous system (brain and spinal cord). A typical example of neuropathic pain due to peripheral nerve injury is phantom pain. Here, an operative or accidental amputation has severed the peripheral nerves. Nerve pain, the cause of which lies centrally in the CNS, can occur in diseases such as multiple sclerosis (MS) or after a stroke (cerebral infarction).
In the course of mental illnesses, such as depression, some sufferers experience pain. However, the cause of the pain here is not in the body, but rather psychological factors. Conversely, persistent pain can also cause depression itself.
Pain receptors (medical technical term: nociceptors) transmit stimuli to the central nervous system (CNS, i.e. brain and spinal cord). The receptors react to temperature stimuli (heat and cold), chemical stimuli and mechanical stimuli (pressure, injuries). The first processing of the signals takes place in the spinal cord and often triggers a reflex, which makes an initial reaction possible. This serves as protection to remove the body from the dangerous situation. In burns, for example, the hand is automatically retracted from the hot source of danger. The information coming from the pain receptors is also transmitted to the brain, which processes it further – in this way an individual pain sensation is created.
Pain perception (nociception)
The feeling of pain (so-called nociception) is always individually pronounced. Using the body’s own messenger substances – for example so-called endorphins – the body is able in certain situations to dampen the sensation of pain. This is where some painkillers come in.
Many people with pain, especially chronic pain, do not go to the doctor. Therefore, no precise information can be given about the frequency. It is estimated that about 1.2 million people in Switzerland suffer from chronic pain. The most common are headaches, followed by back and joint pain.
There are many possible causes of pain, as many different mechanisms can damage the body tissue and thus trigger the sensation of pain: Too low and too high temperatures (e.g. burns), violence (e.g. stab and cut injuries) or toxic substances (e.g. acid) are examples that can cause pain. The sensation of pain, however, is not only a reaction to tissue damage, but also linked to complex processing by the nervous system. Thus, pain can also have psychological causes – and any kind of pain can develop into chronic pain. Pain is defined as chronic if it persists over a period of several months. It often accompanies a disease but persists beyond it. Pain without clear causes is common.
The term psychosomatic includes the words psyche (soul) and soma (body). Psychosomatic illnesses are thus the manifestation of mental problems or illnesses that manifest themselves in physical complaints. The same applies the other way round: physical complaints can in turn lead to psychological problems.
The vegetative nervous system forms a bridge between the psyche and the body. For example, anxiety or stress situations can lead to an increased heartbeat and increased blood circulation. If the overload lasts too long, psychosomatic (somatoform) disorders can occur. If these manifest themselves in permanent pain, a stress situation is created and the vicious circle closes.
Regardless of the cause, pain leads to reflex tension in the respective muscle area. This in turn causes renewed pain, which leads to further muscle tension. Basically, stress causes an increased muscle tension. It has been shown that pain patients have an increased tendency to react to stress with muscle tension and also need longer time to reduce this tension. They therefore show a particular susceptibility to this vicious circle of muscle tension and pain.