Signs and symptoms

Constitutional symptoms are very general and non-specific that can be associated with a wide range of conditions. They include weight loss, headache, pain, fatigue, loss of appetite, night sweats, and malaise. A constitutional symptom may be primary or secondary.

Vital signs are the four signs that can give an immediate measurement of the body”s overall functioning and health status. They are temperature, heart rate, breathing rate, and blood pressure. The ranges of these measurements vary with age, weight, gender and with general health.

A digital application has been developed for use in clinical settings that measures three of the vital signs (not temperature) using just a smart phone, and has been approved by NHS England. The application is registered as Lifelight First, and Lifelight Home is under development (2020) for monitoring-use by people at home using just the camera on their smartphone or tablet. This will additionally measure oxygen saturation and atrial fibrillation. Other devices are then not needed.[8]

Many conditions are indicated by a group of known signs, or signs and symptoms. These can be a group of three known as a triad; a group of four known as a tetrad, and a group of five known as a petrad. An example of a triad is Meltzer's triad presenting purpura a rash, arthralgia painful joints, and myalgia painful and weak muscles. Meltzer's triad indicates the condition cryoglobulinemia. A large number of these groups that can be characteristic of a particular disease are known as a syndrome. Noonan syndrome for example, has a diagnostic set of unique facial and musculoskeletal features.[9]

Sensory symptoms can also be described as positive symptoms, or as negative symptoms depending on whether the symptom is abnormally present such as tingling or itchiness, or abnormally absent such as loss of smell. The following terms are used for negative symptoms – hypoesthesia is a partial loss of sensitivity to moderate stimuli, such as pressure, touch, warmth, cold. Anesthesia is the complete loss of sensitivity to stronger stimuli, such as pinprick. Hypoalgesia (analgesia) is loss of sensation to painful stimuli.[10] Symptoms are also grouped in to negative and positive for some mental disorders such as schizophrenia.[11] Positive symptoms are those that are present in the disorder and are not normally experienced by most individuals and reflects an excess or distortion of normal functions.[12] Examples are hallucinations, delusions, and bizarre behavior. Negative symptoms are functions that are normally found but that are diminished or absent such as apathy and anhedonia.[12]

Radiologic signs are abnormal findings on imaging scanning. These include the Mickey Mouse sign and the Golden S sign.

Cardinal signs and symptoms are those that may be diagnostic, and pathognomic – of a certainty of diagnosis. Inflammation for example has a recognised group of cardinal signs and symptoms,[13] as does exacerbations of chronic bronchitis,[14] and Parkinson's disease.

A reflex is an automatic response in the body to a stimulus.[15] Its absence, reduced (hypoactive), or exaggerated (hyperactive) response can be a sign of damage to the central nervous system or peripheral nervous system. In the patellar reflex (knee-jerk) for example, its reduction or absence is known as Westphal's sign and may indicate damage to lower motor neurons. When the response is exaggerated damage to the upper motor neurons may be indicated.

A number of medical conditions are associated with a distinctive facial expression or appearance known as a facies[16] An example is elfin facies which has facial features like those of the elf, and this may be associated with Williams syndrome, or Donohue syndrome. The most well-known facies is probably the Hippocratic facies that is seen on a person as they near death.[17]

Signs and symptoms may be classified by the type of inference that may be made from their presence, for example:

• Anamnestic signs (from anamnēstikós, ἀναμνηστικός, "able to recall to mind"): signs that (taking into account the current state of a patient's body), indicate the past existence of a certain disease or condition.[18]^:81 Anamnestic signs always point to the past. (As King (1982) explains, whenever we see a man walking with a particular gait, with one arm paralysed in a particular way, we say "This man has had a stroke"; and, if we see a woman in her late 50s with one arm distorted in a particular way, we say "She had polio as a child".[18]^:81)
• Diagnostic signs (from diagnōstikós, διαγνωστικός, "able to distinguish"): signs that lead to the recognition and identification of a disease (i.e., they indicate the name of the disease).[18]^:81
• Pathognomonic signs (from pathognomonikós, παθογνωμονικός, "skilled in diagnosis", derived from páthos, πάθος, "suffering, disease", and gnṓmon, γνώμον, "judge, indicator"): the particular signs whose presence indicates with certainty, that a particular disease is present.[19] They are an intensification of a diagnostic sign. An example is the palmar xanthomata seen on the hands of people with hyperlipoproteinaemia.

"Symptoms become signs when they permit inference. Ordinarily, one single symptom by itself—such as pain or swelling, or discoloration, or bloody discharge—would not permit any specific inference, but when signs and symptoms occur in clusters and form a pattern, then the aggregate might point to a particular disease. The pathognomonic sign, however, does not need any other manifestation to lead the physician to the correct diagnosis. It constitutes a one-to-one relationship—the sign and the disease are uniquely related. The pathognomonic sign was the "clincher", the datum that established the diagnosis unequivocally."[18]^:100

A symptom (from Greek σύμπτωμα, "accident, misfortune, that which befalls",[20] from συμπίπτω, "I befall", from συν- "together, with" and πίπτω, "I fall") is a departure from normal function or feeling. Symptomatology (also called semiology) is a branch of medicine dealing with the signs and symptoms of a disease.[21][22][23] This study also includes the indications of a disease.[24] It was first described as semiotics by Henry Stubbe in 1670 a term now used for the study of sign communication.

Prior to the nineteenth century there was little difference in the powers of observation between physician and patient. Most medical practice was conducted as a co-operative interaction between the physician and patient; this was gradually replaced by a "monolithic consensus of opinion imposed from within the community of medical investigators".[25][26] Whilst each noticed much the same things, the physician had a more informed interpretation of those things: "the physicians knew what the findings meant and the layman did not".[18]^:82

Input from the patient was gradually reduced from the medical interaction[25][26][27] due to significant technological advances such as:

• In 1761 the percussion technique for diagnosing respiratory conditions was discovered by Leopold Auenbrugger.[28] This method of tapping body cavities to note any abnormal sounds had already been in practice for a long time in cardiology.[28] Percussion of the thorax became more widely known after 1808 with the translation of Auenbrugger's work from Latin into French by Jean-Nicolas Corvisart.

• The 1819 introduction by René Laennec (1781–1826) of the technique of auscultation (using a stethoscope to listen to the circulatory and respiratory functions of the body). Laennec's publication was translated into English, 1821–1834, by John Forbes.
• The 1846 introduction by surgeon John Hutchinson (1811–1861) of the spirometer, an apparatus for assessing the mechanical properties of the lungs via measurements of forced exhalation and forced inhalation. (The recorded lung volumes and air flow rates are used to distinguish between restrictive disease (in which the lung volumes are decreased: e.g., cystic fibrosis) and obstructive diseases (in which the lung volume is normal but the air flow rate is impeded; e.g., emphysema).)
• The 1851 invention by Hermann von Helmholtz (1821–1894) of the ophthalmoscope, which allowed physicians to examine the inside of the human eye.
• The (c. 1870) immediate widespread clinical use of Sir Thomas Clifford Allbutt's (1836–1925) six-inch (rather than twelve-inch) pocket clinical thermometer, which he had devised in 1867.[29]
• The 1882 introduction of bacterial cultures by Robert Koch, initially for tuberculosis, being the first laboratory test to confirm bacterial infections.
• The 1895 clinical use of X-rays which began almost immediately after they had been discovered that year by Wilhelm Conrad Röntgen (1845–1923).
• The 1896 introduction of the sphygmomanometer, designed by Scipione Riva-Rocci (1863–1937), to measure blood pressure.

These developments allowed for more objective assessment by the physician in search of a diagnosis.