On some issues of medical semiotics

Current Problems and Their Relevance

The history of medical semiotics (symptomology), which involves the study of signs of disease, i.e. symptoms, is as long as the history of medicine itself. Over the long epoch, a huge amount of evidence has been gathered about signs of disease. The 20th and 21st centuries have seen an extraordinary increase in knowledge, with the number of nosologies rising from a few hundred to many thousands and continuing to grow. As a science, medical semiotics has always been based on empirical research methods: it describes clinical features of diseases and establishes a causal relationship between the observed symptoms and diseases. However, the symptom itself, its meaning, structure, and classification, i.e. the theory of medical semiotics, have been largely neglected.

This was considered appropriate when the first evidence relevant to medicine began to accumulate. However, the challenges of medical practice and the associated difficulties in making use of the vast amounts of evidence already assembled are driving an increase in diagnostic and treatment errors and are encouraging medical science to move from empirical methodology to a formal logic-based analytical interpretation of prior knowledge. One of the first steps toward this goal was the methodology of "evidence-based medicine" (EBM), and the promotion of this approach is expected to lead to the development of so-called "analytical medicine".

When it comes to medical semiotics, this means not only mining the disease-symptom relationship but also studying the symptom itself, its meaning, nature, pattern of occurrence, classification, etc., including methods of EBM. This type of approach requires the development of a formalized conceptual construct of medical semiotics, since the intuitively understood and defined concepts are not applicable to logic-based methods of analysis.

The advances in the theory of general semiotics exemplified by its applications such as mathematical logic, analytic philosophy, linguistics, etc. are a great help to the development of medical semiotics and a significant driving force. Medical semiotics should benefit from incorporating the results of theoretical semiotics by increasing its viability in practical medicine and consequently improving the quality of diagnosis and treatment.

Current Problems of Medical Semiotics

Medical semiotics is currently defined as the theory of signs that discloses the nature and manifestation of diseases (1).

A distinction is made between general and special semiotics. The Great Medical Encyclopedia (3rd edition, edited by Pokrovsky) defines the subject of general semiotics as signs relating to the patient’s general characteristics (sex, age, profession, family history, past medical history, body habitus, sexual development, past history of intoxications) and general appearance (altered state of consciousness, body position, facies, skin color, etc.). General semiotics also studies how changes in organ functioning and morphology are reflected in symptoms.

S.V. Ivanov gives a somewhat different insight into general semiotics [2]. He defines general semiotics as the description and classification of symptoms, methods of their detection, and patterns in terms of pathological processes.

In the Great Medical Encyclopedia (3rd edition, edited by Pokrovsky), the subject of special semiotics of body organs and systems includes symptoms of specific diseases, mechanisms of their development and progression, diagnostic significance, assessment of severity, special aspects of their concomitance, factors for the absence.

S.V. Ivanov wrote [2] that special semiotics describes signs and symptoms of certain diseases.

It should be noted that in his definition of general and special semiotics, S.V. Ivanov, a semiotics theorist, categorized symptom characteristics, classification, mechanisms of development, etc., as general medical semiotics, whereas E.I. Sokolov who represented the clinical-based scholarly traditions recognized these notions to be the subject of special semiotics, which definitely reflects the established practice of a diagnostic method.

A symptom is a fundamental concept of medical semiotics. It is a sign of disease, a qualitatively new event uncharacteristic of a healthy individual. Symptoms can be detected using clinical examination methods to diagnose and/or make a prognosis of the disease [1].

In general semiotics, symptoms are classified into pathological and compensatory, indicative of organic (structural) and functional changes in a substrate, pathognomonic and general in diagnostic significance, early and late in the time of onset [2].

Actually, the extent of prior research in the theoretical framework of modern medical semiotics revolves around all that has been said.

What are the principles and methodology of symptomology according to current medical guidelines and textbooks? What practical aspects does it concern?

As it is commonly believed, medical semiotics as a part of diagnostics refers to its subdivision that deals with disease manifestations. In fact, symptoms themselves and methods of their detection are traditionally presented in general internal medicine, while the symptom-disease relationship is addressed within special pathology. It should be noted that general internal medicine gives symptoms an extremely narrow consideration: only a small subset of more than 2500 currently known symptoms and syndromes is covered. Not surprisingly, the content value of symptoms remains completely unaddressed: with a huge number of symptoms without proper classification, a close scrutiny of the whole range of symptoms and their mechanisms would constitute a competing medicine, which would be inaccessible anyway. The methods of symptom detection, including physical, instrumental, and laboratory, are very superficially discussed, with too little emphasis put on important aspects of symptoms such as their sensitivity and specificity. A prognostic role of symptoms is out of the scope of symptomology presented within general internal medicine. Special symptomology is actually incorporated into one aspect of special pathology and therapy, which completely defies the logic of the cognitive clinical process in diagnosis assuming to result in a specific nosology, not to begin with, so as a physician focuses on a similarity method of diagnosing, other than relies on logical analysis. A number of guidelines and textbooks on the semiology of internal medicine (e.g., Roitberg's Semiology of Internal Medicine, Harrison's Manual of Medicine, semiology handbooks [3–5]) attempted to escape from this paradigm. However, these manuals are not based on the mature theoretical foundation of general medical semiotics and therefore cannot create a consistent physician’s performance in the diagnostic process.

Academician E.I. Sokolov was among those who highlighted current challenges and weak points of the theoretical and practical medical semiotics [1]. He recognized that the development of diagnostic algorithms aimed at automation of these processes revealed indefinite and contradictory patterns of defining such fundamental medical concepts as "health", "illness", "disease", and "symptom". Being elusive, these patterns incorporate sets of synonyms and homonyms. Indefiniteness and inconsistency of the symptom event are also reflected by general semiotics theorists, such as Sebeok [6], Jakobson [7], Roland Barthes [8], and others.

Based on the above, it seems essential and relevant to clarify the theoretical foundations of medical semiotics and its practical aspects.

Medical Semiotics in Relation to Analytical Medicine

Many authors [9][10] have emphasized that the absolutely prevalent empirical methodology is giving way to analytical approaches in medical science and practice. A switch takes place from intuitive paradigms to highly formalized definitions of concepts that reveal their essence. Due to this, they become appropriate for reliable modeling (qualitative or quantitative) of reality, and accordingly, real-world significant results may be obtained. The lack of an analytical approach is specifically responsible for the difficulties that modern medical semiotics are facing.

Subject and Limitations of Medical Semiotics

Discussing the object of medical semiotics, one should proceed from the fact that the subject of medicine is human health and illness [10]. The forms of illness are disease and functional failure [10]. As a substantial event, these two forms appear in various manifestations, by way of which they can be established. Thus, medical semiotics is the study of signs of both a disease and an illness. Since each aspect of the diagnosis of disease and functional failure is quite broad and has unique features, this paper will focus on the medical semiotics of disease. However, when it comes to the semiotics of disease, one should give consideration to the following concept of disease. As the authors have demonstrated earlier, the disease may be defined as a state of imbalance in body functioning. It involves a set of dysfunctional processes resulting from interfering and/or damaging factors (internal or external) as long as the adaptive capabilities and responses of the body aimed at recovering the balance (somatic and/or mental) have been depleted [10]. With that in mind, disease is a conventional name for a typed body state characterized by body imbalance, as well as a range of the above-mentioned features. Thus, there is no substrata such as disease does in the real world. It is a convention, abstraction; however, specific diseases exist as a set of specific processes. Broadly speaking, one should recognize a disease as a diseased condition, medical problem and accordingly as signs of disease specific to the diseased condition. This means that disease per se does not actually exist, but there is a certain general diseased condition that occurs in any disease. When it comes to the signs of a particular disease, it is obvious that it is not a case of nosological classification of disease in its modern sense based on some conditional signs, other than constituent processes. Signs of disease clearly take place and can be indicative of processes that form stable complexes having conditional names given by a physician as coded by ICD 11. In other words, although signs of disease do not naturally exist, there are only signs of disease processes, and the problem consists in defining a nosological unit based on these processes, that is, in transforming them from a natural to the a conditional state.

Let us discuss the concept of "sign of illness", or "sign of disease process".

In mathematics or logic, a sign is a sufficient criterion to classify an object. In less formal sciences, the word "sign" is used to describe facts that make it possible (according to the existing theory) to conclude that the event exists.

Based on insights into medical semiotics, the word "sign" is understood as two different concepts: first, it is a material object, an event indicative of a disease, and second, it is a fact that determines the higher probability of a certain disease due to a causative factor or functional failure (risks of disease development). Accordingly, these signs have different meanings: in the first meaning, it is a sign of a particular disease process, and the second meaning refers to a sign showing triggers for pathological processes.

Medical semiotics is the science of signs indicative of risks of occurrence, presence, form, and nature of illness.

Medical Symptom

For the purposes of the subject of medical semiotics, the concept of "sign" has been used so far. However, in current practice, the term "symptom" is accepted. Are the symptom and sign the same thing or not? It is obvious that a sign of illness, detected by a physician, must come a certain way before medical science and practice recognize it as a quite reliable tool for detecting a particular health disorder, i.e. it becomes a medical symptom. In particular, this has been clearly demonstrated by EBM presenting an idea asserting the unequal importance of individual and group experience and truth. Accordingly, not any sign can become a symptom or tool in medical diagnosis, but only one that is understood, recognized by medical science, verified by medical practice, and meets certain criteria, which will be discussed below.

To understand a symptom event and to define the requirements for a symptom, let us consider it in all its most relevant aspects.

Symptom Functions

Diagnosis can be classified into two categories: preventive and clinical. It focuses on identifying the risks of illness and clinically manifested illness. Accordingly, a symptom works to support the following situations:

1. Increased risk of pathological processes (an active causative factor, functional failure, lower adaptive capabilities, etc.).
2. Presence of disease or functional failure.
3. The direction of diagnostic search.
4. The specific set of body processes combined as a disease or functional failure.

A procedure of diagnosis involves analyzing the symptoms identified by a physician using

current medical knowledge to generate the ultimate reality, where any illness does or does not exist. Thus, the symptom should be indicative of illness, as well as of the specific process and nature of illness.

Symptom Substance

To further understand symptom functioning in the medical knowledge system,

it is critical to define its substance.

In the context of theoretical semiotics, a symptom is a sign. Its substance is to represent another object. As a result, the substance of a medical symptom becomes a representation of illness or risks of illness. What does it mean? When it comes to the representation of risks of illness, certain factors are actually meant that contribute to the onset of pathological processes (a current causative factor, functioning defects resulting in or contributing to the development of pathology, reduction of adaptive capabilities leading to the development of irreversible effects, etc.). Thus, speaking of risk symptoms, one actually refers to signs of events that have occurred, however, not of the pathological consequences themselves, but only those that contribute to their onset, i.e. increase their risk.

In terms of representation of the illness itself, first of all, it means the reference of the illness itself, second, of the type of illness (disease or functional failure), and third, of illness components (i.e. pathological or imbalance-associated adaptive-recovery processes). One is concerned with the nature of the object itself, which is assigned the meaning of a symptom-sign, insofar as it is a result, an effect of the cause it represents, otherwise, one is not interested in the nature of the object (a sign carrier). Giving a specific meaning to the sign with regard to its nature (onset) will be characterized below.

Thus, a symptom is a certain event, an object, which always denotes either an illness or the risk of illness; however, it can contain various amounts of information. If an event, an object that is called a symptom, does not always refer to illness, then it is devoid of any substance, i.e. it is not a sign and therefore not a medical symptom. This may mean that an event is only accidentally considered a symptom, or the event is only a part of the symptom, that there is another component of the symptom that has not been understood or has been missed, and that when it appears, the event becomes a symptom, i.e. a complex event can be a symptom. In other words, a symptom is something that appears every time when there is a represented object. On the other hand, it is known that a disease is a number of pathological and adaptive-recovery processes, and if the pathology alongside causative factors unambiguously determines the nosological form of the disease, i.e. it exists at any moment, then adaptive-recovery processes may vary, as is the case with symptoms (signs of processes) and their severity.

Symptom as a Communicative Phenomenon

Since a medical symptom is a sign (a means of communication, i.e. information transmission), hence, the sign has a message source and a message recipient responsible for the meaning. Viewed in this way, messages may be classified as follows:

1. A message from the body to the body itself, including the consciousness, as the following signs:
   • pain, by which the body informs the consciousness of a traumatic impact or damage;
   • a general feeling of being unwell (diseased condition). Obviously, it is a body signal indicative of an illness and the need to recruit body defense to fight the disease;
   • a message from the body to the consciousness informing on any organ dysfunction (e.g., dizziness, nausea, etc.).
2. A message from the body to the consciousness informing of organ or system overexertion.
3. A message from the body to the body itself (organ-to-organ) can be also transmitted as signs, such as changes in body concentrations (hormones, electrolytes, etc.), regulation, structure, etc. Such messages are not directed to consciousness, and therefore they are insensible. They can be detected and recorded by various methods of investigation (physical and instrumental examination, clinical pathology) and properly interpreted. It is quite clear that body messages informing on injuries, pathological processes, and adaptive-recovery processes are transmitted to various organs and systems, as well as to the consciousness to ensure the termination of the damaging factor action, to save energy to adapt to the injury by changing behavior, to adjust body systems to the injured systems, i.e. to ensure a reasonable response to other body systems. In those cases, when body organs and systems are not supposed to respond to the injury, no signs-symptoms occur. For example, in cancer patients who experience defects in cell reproduction mechanisms resistant to the immune system due to its functional failure, either congenital or acquired, the body does not form any internal signals informing on the pathological situation because there are no mechanisms for the immune system recovery.
4. An echo message (echo symptoms) is a message transmitted by a physician to him/herself in such a way that it is reflected from the object investigated and the nature of the reflection (change of the message) could give a basis to pass judgment on the object. In this case, the meaning and significance of the symptom are given by the physician and may be interpreted only in this context. The message (symptom) may be generated, transmitted, and received in the sign system which ensures the interaction between the body and this system. For example, when it comes to organ structure, this is the language of ultrasound or X-ray, and referring to body fluids, this is magnetic resonance imaging (MRI), etc. Of course, when a physician generates a message to the body, he/she uses the language and concepts of medical science, which must be transformed into the language and concepts of special medical diagnostic systems (ultrasound, X-ray, MRI, computed tomography, positron emission tomography (PET), clinical pathology, etc.). This is usually done by a medical specialist. However, the scope of his/her responsibilities includes the translation of body messages generated by the treating physician using the concepts of appropriate methods, transmitting the body message, receiving the echo message, and translating it into the language of medical concepts. That is to say, the specialist is expected to receive the echo symptom as directed by the treating physician.

Symptom Characteristics

As previously stated, a symptom (a material object or event) is a sign of some event or object as agreed by the message source and recipient. Accordingly, all symptom characteristics, other than those of the material object itself (a sign function carrier) occur and can be regarded only in the context of source and recipient. Hence, the following symptom characteristics can be distinguished: meaning conveying, representativeness, and definiteness. They are discussed below.

Symptom Characteristic to Convey Meaning

Based on this characteristic, signs (symptoms) are divided into iconic, indexical, and symbolic.

Iconic symptoms are duplicate symptoms, such as skin diseases or open wounds. What one sees is not the entire lesion, pathologic process, or other processes that constitute the disease, but only their manifestation on the skin or body surface. An iconic symptom is a copy, with its details neglected; it is unscaled. However, it is a print, which shows the original unequivocally.

An indexical symptom results from the interaction with a root cause (extensional), and a process that underlies the disease (like snow footprints or fire smoke). For example, diarrhea in intestinal infection, throat hyperemia in infection, etc. Owing to the mechanism of iconic and indexical symptoms, they are always present if the extensional is available. Indexical symptoms imply the presence of a disease process or nature (substrate) and characterize this substrate, i.e. they contain information describing the fact and its characteristics. Indexical symptoms, similar to iconic symptoms, are pitchy.

Symbolic symptoms are generated solely to put people’s agreement into practice. Significance and meaning are assigned to a sign artificially. The scope of significance and meaning is also allocated as a result of the agreement. A sign (symbol) is an abstraction, poor in content. Apart from the meaning assigned, it has no other content. Unlike indexical and iconic symptoms, the association between the symbolic symptom and extensional has not become recognized, but experienced empirically. For example, phantom pains, tension headaches, etc. This opens the door for association errors and unrecognized patterns, whereas symptoms do or do not exist, or accompany another disease. It should be noted that in medicine, historically all symptoms refer to either iconic or symbolic groups. As mechanisms of body structure and functioning have become known, some symptoms switched to indexical, and some symptoms terminated to be so.

Symbols may have the following meanings: injurious exposure, body injury, body dysfunction signals, pathological process location, adaptive-recovery process location, functional failure and its type, and the type of pathological or adaptive-recovery processes. The meaning of a symptom is different from its significance. A symptom denotes a particular material substrate (process or its content), whereas meaning is an ideal interpretation of these events.

The following levels of the meaning of a medical symptom can be distinguished. The first level of meaning is a message of body injury, dysfunction, and illness (pain, dizziness, etc.). The second level of meaning of a symptom is a message of the anatomical and functional injury location. The third level of meaning is a message of a specific substrate signified by a symptom. It may have a symptom-related meaning or all meanings at a time.

Representativeness

Concerning that a symptom is able to represent an object, it should be noted that due to the mechanism of iconic and indexical signs, they always represent the things they signify, i.e. the symptom may not exist while the object to be represented does not. In medicine, a patient often presents with symptoms described in guidelines, however, is finally diagnosed with the other disease. This scenario can be explained by misidentification of the symptom, otherwise, the symptom is taken as a sign of a processes-disease complex, which is actually a sign of only one process characteristic of many diseases.

The representativeness of sign-symbols should be considered differently, where their representativeness is agreed upon, so the relations between the symptom and the represented object have not been objectively defined. In this case, it is essential to verify symbolic symptoms by methods of EBM.

It should be noted that in contrast to the scenario, in which "here is a symptom, so there is also an object it represents", the opposite is not equivalent: a process that constitutes a disease is present, however, no symptoms are observed. This situation is possible if the mechanisms of symptom formation have been disturbed.

Definiteness

Since a symptom is a material object or event, it can be characterized by definiteness, by which it can be distinguished from other objects or events. This means, e.g., that pain itself cannot be a symptom, but only specific (of a definite kind) pain can be a symptom.

Direct and Indirect Symptoms

Iconic and indexical symptoms are formed by duplicating or reflecting the extensional, i.e. signs bear the imprint of the represented object. Understanding the mechanisms of symptom formation should be associated with knowing all aspects of the events or non-occurrence of the sign and the meaning contained. Such symptoms are referred to as direct symptoms. In contrast, symbolic signs (iconic signs, indexical signs), with their mechanisms not completely clear, are indirect. It is not as if their patterns and meaning are definitely understood. They are referred to as indirect because the sign relative to the extensional is mediated by unknown processes. Based on the above, the pattern of direct symptoms is always definite, while that of indirect symptoms is unknown. However, in practice, it is true for direct symptoms to be absent in those scenarios where they are highly expected. This may be due to signaling system dysfunction, a combination of additional pathological processes, medication effects, etc.

Symptom Definition

A symptom may be defined as follows. It is a message from a patient's body element to the consciousness and/or other body elements, or a physician’s echo message as a certain sign informing on disease-associated processes, their characteristics, and nature, which have been verified in scientific and practical medicine and properly recognized as such.

Semiotics in Medicine

It is evident that semiotics is attributable to the needs of diagnostics, however, it does not confine to diagnostics alone: semiotics is one of the sources to generate the language of medicine — both vocabulary and meaning. These aspects of semiotics are described below.

Semiotics and Diagnosis

In analytic methodology, the physician's way from the patient’s complaint to diagnosis differs from that of the "similarity"-based methodology. In the latter case, the physician interviews his/her patient to record complaints and medical history, reports physical examination data, and eventually, makes attempts to remember what the set of symptoms that have been detected resembles and matches this set with diseases that have come to his/her mind. In the analytical approach, the sequence and logic of the diagnostic process are quite different. First of all, the physician objectifies and formalizes the patient's complaints into symptoms, identifies their meaning and significance, and in this stage, he/she makes attempts to understand whether the presented complaints can be referred to as symptoms or not. In other words, the physician elucidates if the patient does or does not have a disease. In the next stage, the physician combines the patient’s complaints with medical history and physical examination findings, looks for additional symptoms, and analyzes their meaning to identify the anatomical and physiological location of the processes that constitute the disease. Finally, he/she seeks for clinical pathology and instrumental examinations to obtain echo symptoms, and finally verifies the disease.

Obviously, this different approach to the diagnosis methodology makes one understand the symptom phenomenon in a completely different way. Although in the first case, the symptom itself means nothing for the most part (it is the set of symptoms that matters), in the second case, the symptom becomes significant and meaningful both by itself and as a whole. However, it is also important to name the symptom correctly in order to define it correctly. Currently, the medical language uses many imprecise, vague, and therefore indefinite terms to describe symptoms. As has been said, a symbolic symptom is a material object, hence it is specific, and a specific object is individual. Thus, it must be denoted individually (precisely). Replacing the precise term of a symptom with a common name (e.g., "pain", "dizziness", etc.) results in the loss of both symptom significance and its meaning. Hence, another objective of semiotics is to generate a contemporary language of medicine.

Semiotics and Language of Medicine

The language of medicine is a special language, with unambiguity and accuracy being its essential properties. Its targeted users are millions of people. Accordingly, it is a critical mission of medical science to generate it. In medicine, this should obviously be a responsibility of semiotics as a science of signs. It establishes rules for denoting and disclosing meanings of symbols and processes that constitute illness, names of diseases, and functional failures. In addition, semiotics aims at establishing translation rules and meaning of symptoms from the medical language to special technical languages of those disciplines that help medicine in diagnosis and treatment, such as ultrasound, MRI, PET, etc.

Conflict of interest. The authors declare no conflict of interest.