Psychogenic Regulation of Pain Sensation
The intensity of perceived pain largely depends on higher nervous activity. Psychogenic regulation includes cortical influences and the dependence of sensory thresholds on a person's current emotional state.
Cortical regulation is clearly manifested through the so-called expectancy effect. If a patient is warned in advance about an upcoming painful procedure, they are able to psychologically prepare, which objectively facilitates tolerance of the procedure. The physiological mechanism of this phenomenon relies on descending corticofugal influences. Signals originating predominantly from the somatosensory cortex activate the endogenous antinociceptive (pain-relieving) systems of the brain, primarily the opioid and serotonergic systems.
Emotional regulation features heterogeneous mechanisms. Any emotional experience can shift pain sensitivity thresholds, and the nature of analgesia is determined by which specific emotion-generating areas are involved in the process:
- A normal positive emotional state (upon activation of positive emotion-generating sites) provides an antinociceptive effect primarily through the activation of the opioid mechanism.
- If a positive emotion is coupled with pronounced motivational arousal, pain suppression is realized predominantly through the adrenergic mechanism.
Main Methods of Pain Relief
Methods of combating pain syndromes are classified according to the nature of the intervention and the level at which the nociceptive signal is interrupted.
Physical methods include basic non-invasive procedures: strict immobilization of the injured area, temperature therapies (both warming and cooling), massage, and special exercises aimed at reducing muscle tension. Diathermy—shortwave radiation—is successfully used to warm deeply located tissues.
Pharmacological and surgical methods aim at the physiological blockade of pain transmission at various levels of the nervous system:
- At the periphery: local anesthetics are used, which completely prevent the generation and conduction of nociceptive impulses from receptors.
- Along ascending pathways: nociceptive excitation is blocked at the spinal cord level (e.g., via lumbar anesthesia).
- In the brain: general anesthesia is used, exerting a direct inhibitory effect on the neurons of structures responsible for perceiving nociceptive stimuli.
Neurosurgical measures (such as cordotomy) are resorted to extremely rarely. Because such operations are irreversible, they are used exclusively to relieve suffering in patients with intractable chronic pain.
Non-pharmacological methods have recently been gaining popularity. These include acupuncture, the exact mechanisms of which are still not fully understood, as well as transcutaneous electrical nerve stimulation (TENS). Electrical stimulation of sensory pathways of the spinal cord is also distinguished, requiring the implantation of stimulating electrodes into the dorsal columns of the spinal cord or into the periaqueductal gray matter of the brainstem to externally activate antinociceptive neurons.
Mechanisms of Pain Perception Facilitation
In addition to pain-suppressing systems, the body possesses mechanisms that enhance pain sensitivity. One of the key processes is sensitization.
Sensitization typically occurs in response to repeated exposure to a damaging painful stimulus. This phenomenon is based on the massive release of specific mediators from destroyed tissue cells. Potassium ions, serotonin, bradykinin, histamine, and other active substances enter the intercellular space. They bind to membrane receptors on afferent nociceptive fibers, leading to a sharp increase in their sensitivity to pain.
Furthermore, central modulation exists. Ultimate pain perception, as well as the severity of somatic and autonomic protective responses, depends on the dynamic balance between central mechanisms that inhibit and facilitate pain. The activation mechanism of pain facilitation is often triggered by sustained afferentation, predominantly of low intensity. Such signals can enter the central nervous system via the vagus and glossopharyngeal nerves (including impulses from baroreceptors located in high-pressure blood vessels).
Prevention of Negative Emotions
Since the emotional background is critical for pain modulation, attention must be paid to addressing negative experiences. Most popular recommendations focus on managing already established negative emotions.
However, true prevention implies completely preventing the emergence of a negative emotion in a given situation. Achieving this goal requires two basic prerequisites: first, the purposeful cultivation of an emotional culture, and second, the development of a conscious, responsible attitude by an individual toward unfolding circumstances.