The term functional disorders should be revitalised

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    A new definition of 'functional disorder' refers to changes to the functioning of the nervous system and other organ systems. This understanding has now gained wider acceptance among patients and the medical community, but the continued use of outdated terminology is still causing confusion and misunderstandings.

    Illustration: Mimomy/iStock. Edited by the Journal of the Norwegian Medical Association
    Illustration: Mimomy/iStock. Edited by the Journal of the Norwegian Medical Association

    In medicine, the word functional has been used to describe somatic symptoms when standard investigations have failed to detect a pathologic basis in the traditional biomedical sense (1–3). Such symptoms are commonplace, accounting for approximately one-third of consultations in both primary care and the specialist health service (4,5). Examples include headaches, gastrointestinal discomfort, dizziness, fatigue, difficulty concentrating, seizures, paralysis and sensory disturbances. The severity ranges from mild and transient to severe chronic conditions, affecting 1–2 % of the population (6,7).

    Terms throughout history

    Terms throughout history

    Throughout history, a confusing array of closely related, sometimes overlapping terms have been used to describe such symptoms and conditions. Interestingly, the term functional was originally used in the early nineteenth century to specifically describe alterations in the functioning of the nervous system (8). Over the course of the nineteenth century, the meaning of the word evolved into an antonym for organic, as a way of explaining somatic symptoms without a demonstrable physical cause.

    At the same time, women with non-specific bodily and emotional symptoms were often diagnosed with hysteria, a term rooted in antiquity, where it was believed the symptoms stemmed from a wandering uterus. Hysterical neurosis evolved into a psychoanalytic term for bodily symptoms arising from underlying psychological conflicts, meaning they were psychogenic in nature. The diagnosis was included in early versions of the ICD (International Classification of Diseases) and DSM (Diagnostic and Statistical Manual of Mental Disorders) until the 1970s.

    In the late nineteenth century, Sigmund Freud (1856–1939) and Pierre Janet (1859–1947) introduced the concepts of conversion and dissociation as defence mechanisms against psychological stress. In conversion, psychological stress was 'converted' into physical symptoms, while dissociation entailed changes in consciousness and memory with a temporary 'disconnect' from reality, thoughts, feelings or sense of identity. These terms were incorporated into international diagnostic classification systems, initially as subcategories of hysterical neurosis. Somatoform disorders, which also refer to physical symptoms with psychological origins, was introduced in DSM-III (1980) and ICD-10 (1992, still used in Norway). This category was intended to be more precise and less burdened by the historical and cultural connotations of hysteria.

    The term psychosomatic has a long tradition and has been used both as an umbrella term to describe how psychological factors and processes affect the body's physiology and to characterise symptoms without a demonstrable physical explanation (9). The term medically unexplained symptoms has been in use since the 1990s. It was introduced to reflect the fact that some symptoms may not necessarily have a clear biomedical cause but are still real and can have a major impact on a patient's quality of life (10).

    No longer medically unexplained

    No longer medically unexplained

    Research in recent decades has provided deeper insights into causes and mechanisms, showing that they are no longer considered 'medically unexplained'. Cumulative biopsychosocial stress, genetic factors and epigenetic changes impact susceptibility to developing the symptoms. Studies using advanced methods have revealed changes in brain networks and the body's physiology (11,12). There are strong indications that these may be closely related conditions or subcategories with many shared underlying factors (5,13,14).

    It has been proposed that the term functional disorders be used as an umbrella term that encompasses various physical symptoms

    Such symptoms can arise from any of the body's organ systems and are therefore represented in nearly all medical specialties. Accordingly, it has been proposed that the term functional disorders be used as an umbrella term that encompasses various physical symptoms (Box 1) (5,15). For example, the international gastroenterology community has, since the 1990s, been developing recognised symptom-based criteria, known as the Rome criteria, for functional gastrointestinal conditions (16).

    Box 1 List of diagnostic codes for functional disorders in the Danish ICD-10

    DR688A9 Functional disorder NOS

    DR688A9A Functional disorder, multiorgan

    DR688A9B Functional disorder, single organ

    DR688A9B1 Functional disorder, general/fatigue

    DR688A9B2 Functional disorder, gastrointestinal

    DR688A9B3 Functional disorder, musculoskeletal

    DR688A9B4 Functional disorder, cardiopulmonary

    DR688A9B5 Functional disorder, neurological

    DR688A9B6 Functional disorder, urogenital

    DR688A9B9 Other functional disorder, single organ

    DR688A9C Functional disorder, single symptom

    Today's challenge

    Today's challenge

    Today's challenge is that many outdated terms are still in use – across diagnostic classification systems, among healthcare personnel and within the general population. According to ICD-10, which is used in Norway, several functional symptom profiles are classified under the main categories of somatoform disorders and dissociative (conversion) disorders. However, many clinicians and patients find that terms such as conversion, dissociation and somatoform are not well defined, leading to vague and inconsistent use. In contrast, functional disorder is not an established diagnostic category in our classification system but is widely used in clinical practice – primarily in line with the traditional understanding.

    Common to all these terms, including functional as used in the traditional definition, is that they reflect something medically unexplained and psychogenic. This can give the impression that what the patient is experiencing is not fully understood and may be perceived as an indication that the symptoms are not real and just 'in their head'. Use of these terms also perpetuates an artificial, reductionist dichotomy between body and mind, which is incompatible with modern medical knowledge and understanding.

    The euphemistic treadmill

    The euphemistic treadmill

    To counteract stigmatisation and this false dichotomy, new terms have been continually introduced throughout history. Many have advocated for discarding terms such as somatoform, psychogenic, medically unexplained and functional, while introducing terms like complex symptom disorders (a term proposed for use in Norway) (17,18). Others propose terms that specify what the patient's symptoms are not, for example, non-epileptic seizures and non-cardiac chest pain (19). However, whether these represent anything other than superficial changes and euphemisms is debatable. The term euphemistic treadmill is used to describe the constant search for new words to replace those that are taboo, only for the new words themselves to eventually be superseded because they too acquire negative connotations.

    Euphemistic treadmill is used to describe the constant search for new words to replace those that are taboo, only for the new words themselves to eventually be superseded because they too acquire negative connotations

    Providing an acceptable explanation for and naming a patient's symptoms are key components of the diagnostic and therapeutic process. However, name changes alone cannot address the fundamental challenges associated with understanding and treating complex functional symptoms; they need to be accompanied by a deeper and more comprehensive shift in how healthcare personnel and society at large perceive these conditions.

    Finding terms that are both unambiguous and comprehensive is a challenge in many areas of medicine (5,20). Clinical investigations often conclude with phrases like 'no cause found', or descriptions of the condition as 'complex', or explanations of the patient's symptoms based on what they are not. Such practices often become an unfortunate endpoint in the diagnostic process and fail to provide patients with a meaningful explanation for their symptoms. Many patients are left feeling offended, dismissed and disbelieved, leading to misunderstandings and a lack of trust in the patient-doctor relationship (21–23).

    A pragmatic solution

    A pragmatic solution

    The challenges associated with finding terms for medical conditions are well-known and have been the subject of debate for decades. Finding a solution that garners broad consensus has proved to be difficult. However, reputable medical communities in Europe, the United States, Australia and the Nordic countries have now agreed on the term functional, but with a new definition: an altered function of the nervous system and other organ systems (5,11,24). This updated definition paves the way for a biopsychosocial understanding of the disease and reflects the natural reversibility of the symptoms.

    Studies and clinical experience indicate that patients perceive the term 'functional' as neutral and inoffensive

    Studies and clinical experience indicate that, contrary to what many doctors believe, patients perceive the term 'functional' as neutral and inoffensive when it is explained to them (22,23). The term is also well-known among medical personnel. Based on this, Denmark introduced its own diagnostic codes for functional disorders in its 2019 version of ICD-10 (25). The diagnostic codes were grouped into a neutral chapter, separate from the chapters for mental disorders and diseases of specific organs (Box 1). This is a pragmatic solution to bringing together many of the partially overlapping terms currently in use. It also aligns with developments in DSM-5 and ICD-11, both of which have introduced functional neurological disorder as a separate diagnosis (11).

    The word functional should be revitalised

    The word functional should be revitalised

    Universal terminology and nomenclature are essential for ensuring clarity, precision and quality in diagnostics, treatment, research and communication within the field of functional disorders. Agreeing on a common international term across medical disciplines is challenging but necessary. We support the work initiated by leading international medical communities. Revitalising the term functional is an important step in the right direction.

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