Theories of Pain
Gate Theory of Pain: The gate theory of pain attempts to account for the specificity of pain, different types of pain, and the important role of physiological factors. The central assumption of this theory is that different parts of the central nervous system are involved in the pain experience. They affect the operation of a gate-like mechanism in the dorsal horns of the spinal column that controls the flow of pain stimulation to the brain. According to the theory pain is not a sensation that is transmitted directly from peripheral nerve endings to the brain. Sensations are modified as they are conducted to the brain by way of the spinal chord, and they are influenced by downward pathways from the brain that interpret the experience.
In the absence of pain peripheral nerve endings pick up sensations from our physical actions such as touching or walking. The sensations are transmitted via multiple neural pathways to the spinal column, then carried up the column to the brain. The spinal gating mechanism that controls pain is closed. When the peripheral nerve endings are exposed to injurous stimuli, multiple pathways are activated and sensations transmitted to the spinal column. If the patterns of stimulation are sufficiently intense to make the sensations reach a certain threshold and if the brain interprets the event as painful, then the gate will open and the sensation of pain will be transmitted up the spinal chord to the brain.
The theory acknowledges some degree of specificity in the pain transmission system (pain differs in their qualities). It allows for the role of psychological processes in the pain experience.
It helps explain the different kinds of pain that individuals experience
Neurochemical Bases of Pain and its Inhibition
Melzack and Wall (1965,1982) maintained that the brain can control the amount of pain an individual exexperiences by transmitting messages down the spinal chord to block the transmission of pain signals. If the brain is electrically stimulating a portion of the brain, then pain may not be felt. This is called stimulation produced algesia.
Endogenous opioids are neurochemicals important in the natural pain suppressing system of the body. It is not always in operation. Particular factors trigger its arousal.
The release of endogenous opioids may be one of the mechanisms underlying various techniques of pain control.
Opioid drugs do not appear to be particularly successful in relieving noncancer pain, but they may be successful in relieving cancer pain.
Measuring Pain
One barrier to the treatment of pain is the difficulty people have describing it objectively. People experience pain differently. In measuring pain the large informal vocabulary needs to be drawn on. This can be used by medical practitioners to try and understand patients complaints.
Interviews are used to measure pain, but because of subjective experiences this can be problematic, lacking a set standard for what is pain.
Pain questionnaires are used. They provide information on the nature of pain example throbbing or shooting as well as its intensity.
Pain scales have also been used to measure pain. It takes into account behavioural data and psychological data that are helpful for diagnosis and treatment. For e.g the children’s headache scale. This significance of this approach is that it properly recognizes pain as complex experience that is not just a reaction to physical damage but also a result of the physiological and behavioural fallout that pain often creates.
Managing Pain
Surgical control of Pain: This involves cutting lesions in the so-called pain fibres at various points in the body so that pain sensations can no longer be conducted. Some surgical techniques attempt to disrupt the conduct of pain from the periphery to the spinal chord, whereas others are designed to interrupt the flow of pain sensations from the spinal chord upward to the brain. The effects of these surgical techniques are normally short lived.
Surgery is expensive and can possibly worsen the problem, because of damage to the nervous system. This damage can cause chronic pain.
Pharmacological control of pain: The administration of drugs. Any drug that can influence neural transmission is a candidate for pain relief. Some drugs can influence transmission of pain impulses from peripheral nerve receptors to the spinal chord. The application of an analgesic to a wound is an example of this.
Antidepressants are also used to control pain.
Problems, persons can develop addictions to prescription drugs.
Relaxation Techniques: Relaxation training has been employed with pain patients extensively, either alone or in concert with other pain control techniques. Relaxation aids in coping with stress and anxiety which can cause pain to worsen. Controlled breathing, from short shallow breaths to deeper longer breaths. For example childbirth techniques.
Hypnosis: Hypnosis produces a relaxation engendered trance. Patients are told (power of suggestion) that hypnosis will reduce pain. Hypnosis is itself a distraction from the pain experience of pain.
Hypnosis has been successful in control acute pain due to surgery, childbirth, dental procedures and headaches.
Guided imagery: A patient is instructed to conjure up a picture that he or she holds in mind during the painful experience. The patient is encouraged to visualize a peaceful, relatively unchanging scene, to hold it in mind, and to focus on it fully. Guided imagery can control slow-rising pains that can be anticipated and prepared for, or it can be used to control the discomfort of a painful medical procedure. For e.g advocates of prepared childbirth encourage the woman in labour to develop a focal point a real or imagined picture that she can focus on fully when labour pains begin.
