Pain and semiologic subjectivity
Can we certainty establish what is measurable and what is not?
First of all, we need to clearly define what the measurement is: this is the assignment of a range of values to a particular physical property, also called measuring. This simple concept can be applied very intuitively to surfaces, lengths, weights, temperatures or a simple count, such as red blood cells, but everything changes when to measure or quantify something subjective as pain.
Incidentally, the measurement is practical and everyday necessity, fundamental both in the clinical setting and in the medical and scientific studies. In addition, it is clear that the painful symptoms is an important parameter and is part of several clinical trials. Thus, it becomes necessary to establish a method to have reliable data, less random and with a slight sensitivity in pain symptoms´ evaluation. Such data is actually essential in a disease diagnosis, to establish the validity of a surgical procedure ( e.g. , are compared two types of surgery, evaluating the postoperative discomfort ) , and also are statistically evaluated to reach appropriate conclusions procedure.
In this case, the question to ask is: how can you measure something immeasurable?
The fact that the painful symptoms be a subjective personal experience and closely involves quantifying the symptom with values more or less filled with individual objectivity in general not easily quantifiable and standard able by doctors and researchers . In short, it is very difficult to measure and evaluate pain at all, unless:
- is based on the patient's pain sensation description and thus a self-description deriving from the dialogue with him. In this case a verbal symptom is evaluated;
- are observed the patient reactions against the pain, which can be many: the person cannot move the jaw because of the pain in mandibular joint, facial activity may be altered because of pain symptomatology, the position of a member may be unnatural due to distortion of a shoulder joint or arm, a sleep -wake rhythm can be changed due to a central or peripheral chronic pain. In such cases, the doctor observes the physical attitudes and living conditions changed because of the pain. These symptoms correspond to non- verbal symptom;
- are used in special appliances, such as functional magnetic resonance imaging to visualize the brain areas involved in the transduction of pain signal activation. Obviously do not apply in everyday practice for economic and practical reasons.
Within a patient with pain clinics reviews may be an instrumental support, which, while not directly evaluating the measuring (hence pain), can facilitate their understanding. Instruments such as the pressure on the trigger point’s examination really allow further pain analysis.
Anamnesis ratings represent the essential steps for a correct painful symptoms interpretation and a more examined patient's personality measured knowledge, but it is by applying tests that get a precise measurement of pain.
First of all, we observe what pain is. According to the definition of the International Association for the Study of Pain (IASP - International Association for the Study of Pain) from 1986 and according to the World Health Organization (WHO), "Pain is an unpleasant sensory and emotional experience, associated with tissue damage in the act or potential, or described in terms of injury". It cannot be described as an exclusively sensory phenomena of endogenous and / or exogenous nature but must be seen as the composition:
- a perceptual portion (nociception) which is the sensory modality "pure", which allows reception and transport to the central nervous system potentially injurious stimuli to the body;
- in an experiential part, therefore fully staffed , the true pain experience, which is the psychic state connected to the perception and the development of an unpleasant sensation.
The pain perceptual component or neurological component consists by three-circuit neurons that send the painful stimulation from the periphery to the cerebral cortex.
By the spinothalamic tracts, from the thalamus algógenos signals reach the limbic system, which are designed as emotional and conscious elements. The emotional experiential and parts of pain or psychic component responsible for the subjective assessment and critical algógeno pulse, refer to the limbic system, which is a set of complex structures surrounding the brain stem. The projection of algógenos signals in the limbic system is always the basis for the effect it has on the state of pain of mind, letting them restless and unhappy individuals. In contrast, the limbic system also determines the level of conscious perception of pain. Who is euphoric or shock feels no pain and, instead, who is anxious or hypochondriac feels sharply even minimum harmful stimuli. In fact, some studies show as listening to music, influencing the mood, you can vary the intensity of postoperative pain and anxiety pre-operative.1
Pain is not only physiologically controlled by the nervous system, but also by hormonal, immune and endocrinometabólicos systems. This could explain the large difference in pain of reading between the sexes, as evidenced by average values of the various reading ranges of algógenos stimuli that would result significantly higher in female patients.2
Therefore, the experience of pain is determined by cognitive and affective dimension, by past experience, the mental and emotional structure and sociocultural factors.
The neurophysiological standpoint, the pain symptoms it is vital for functional and homeostatic harmony of living beings. It is primarily an essential defense system to avoid and prevent organic and biological damage, but becomes pathological when it self remains.
Source: Dentista Hoje, written by Doctors: Dario Costantino, Lorenzo Azzi, Gianpaolo Bombeccari, Francesco Spadari e Giovanni Zucchelli
Image takes from: http://www.dentistahoje.com.br/dor-e-subjetividade-semiologica/