Pain management and regulation

Psychogenic regulation of pain sensation

The intensity of perceived pain largely depends on higher nervous activity. Psychogenic regulation includes cortical influence and the dependence of sensitivity thresholds on a person's current emotional state.

Cortical regulation is clearly manifested through the so-called expectation effect. If a patient is warned in advance about an upcoming painful stimulus, they are able to mentally prepare, which objectively improves tolerance to the procedure. The physiological mechanism of this phenomenon lies in descending cortico-fugal influences. Signals originating predominantly from the somatosensory cortex fields activate endogenous antinociceptive (pain-relieving) systems of the brain, primarily the opioid and serotonergic systems.

Emotional regulation is characterized by the heterogeneity of its mechanisms. Any emotional experiences can shift pain sensitivity thresholds, while the nature of pain relief is determined by which specific emotion-generating zones are involved in the process:

• A normal positive emotional state (upon activation of positive emotion-generating points) provides an antinociceptive effect mainly through the activation of the opioid mechanism.
• However, if the positive emotion is coupled with pronounced motivational arousal, pain suppression is achieved predominantly via the adrenergic mechanism.

Basic pain relief measures

Methods of managing 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 easing muscle tension. Diathermy — shortwave radiation — is successfully used to warm deeply situated tissues.

Pharmacological and surgical methods aim at the physiological blockade of pain transmission at various levels of the nervous system:

1. At the periphery: local anesthetics are used, which completely prevent the generation and conduction of nociceptive impulses from receptors.
2. Along ascending pathways: blocking nociceptive excitation at the spinal cord level (e.g., via lumbar anesthesia) is utilized.
3. In the brain: general anesthesia is used, exerting a direct depressant effect on the neurons of structures responsible for perceiving nociceptive stimuli.

Neurosurgical procedures (such as cordotomy) are extremely rare. Because such surgeries are irreversible, they are used exclusively to relieve suffering in patients with agonizing chronic pain.

Non-pharmacological methods have been gaining increasing popularity recently. These include acupuncture, the precise mechanisms of which are still not fully understood, as well as transcutaneous electrical nerve stimulation (TENS). Electrical stimulation of the sensory pathways of the spinal cord is considered separately; it requires the implantation of stimulating electrodes into the dorsal columns of the spinal cord or into the periaqueductal gray matter to externally activate antinociceptive neurons.

Mechanisms facilitating pain perception

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 pain 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 of the afferent nociceptive fiber, leading to a sharp increase in its sensitivity to pain.

In addition, central modulation exists. Final 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 mechanism of facilitating pain perception 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 high-pressure vascular baroreceptors).

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 halting already existing negative emotions.

However, true prevention implies completely preventing the onset of a negative emotion in a given situation. Achieving this goal requires two basic conditions: first, the targeted cultivation of an emotional culture, and second, the formation of a conscious, responsible attitude toward unfolding circumstances.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Anatomic pathways of cortico-fugal influences from the somatosensory cortex on endogenous antinociceptive systems.
• Neurochemical differences in the functioning of opioid and adrenergic pain relief mechanisms under different emotional states.
• Physiological basis and indications for chordotomy in chronic pain.
• The role of afferentation from high-pressure vascular baroreceptors via the glossopharyngeal and vagus nerves in the central modulation of pain.
• Mechanisms of receptor binding of bradykinin, histamine, and serotonin during nociceptive fiber sensitization.

Other topics in the "Pain" section

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