Phenomenon

Phenomenon

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A phenomenon (PL: phenomena), sometimes spelled phaenomenon, is an observable event.[1] The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which cannot be directly observed. Kant was heavily influenced by Gottfried Wilhelm Leibniz in this part of his philosophy, in which phenomenon and noumenon serve as interrelated technical terms. Far predating this, the ancient Greek Pyrrhonist philosopher Sextus Empiricus also used phenomenon and noumenon as interrelated technical terms.

In popular usage, a phenomenon often refers to an extraordinary event. The term is most commonly used to refer to occurrences that at first defy explanation or baffle the observer. According to the Dictionary of Visual Discourse:[2]

In ordinary language 'phenomenon/phenomena' refer to any occurrence worthy of note and investigation, typically an untoward or unusual event, person or fact that is of special significance or otherwise notable.

In modern philosophical use, the term phenomena means things as they are experienced through the senses and processed by the mind as distinct from things in and of themselves (noumena). In his inaugural dissertation, titled On the Form and Principles of the Sensible and Intelligible World, Immanuel Kant (1770) theorizes that the human mind is restricted to the logical world and thus can only interpret and understand occurrences according to their physical appearances. He wrote that humans could infer only as much as their senses allowed, but not experience the actual object itself.[3] This may make sense in terms of a communications-channel (epistemology) feeding from an ensemble of inputs (ontology) yet not in the sense of applying wise imagination (à la Albert Einstein, to partial success).[citation needed] Thus, the term phenomenon refers to any incident deserving of inquiry and investigation, especially processes and events which are particularly unusual or of distinctive importance.[2]

In scientific usage, a phenomenon is any event that is observable, including the use of instrumentation to observe, record, or compile data. Especially in physics, the study of a phenomenon may be described as measurements related to matter, energy, or time, such as Isaac Newton's observations of the moon's orbit and of gravity; or Galileo Galilei's observations of the motion of a pendulum.[4]

In natural sciences, a phenomenon is an observable happening or event. Often, this term is used without considering the causes of a particular event. Example of a physical phenomenon is an observable phenomenon of the lunar orbit or the phenomenon of oscillations of a pendulum.[4]

Secondary Raynaud's. Also called Raynaud's phenomenon, this form develops because of another health condition. Although secondary Raynaud's is less common than the primary form, it tends to be more serious.

processing.... Drugs & Diseases > Rheumatology Raynaud Phenomenon Updated: Aug 04, 2022 Author: Heather Hansen-Dispenza, MD; Chief Editor: Herbert S Diamond, MD more... Share Print Feedback Close Facebook Twitter LinkedIn WhatsApp Email webmd.ads2.defineAd({id: 'ads-pos-421-sfp',pos: 421}); Sections Raynaud Phenomenon Sections Raynaud Phenomenon Overview Practice Essentials Pathophysiology Etiology Epidemiology Prognosis Patient Education Show All Presentation History Physical Examination Show All DDx Workup Approach Considerations Laboratory Studies Magnetic Resonance Imaging Show All Treatment Approach Considerations Nonpharmacologic Therapy Pharmacologic Therapy Treatment of Critical Digital Ischemia Consultations Diet Show All Medication Medication Summary Calcium channel blockers Prostaglandins Nitrates, Angina Phosphodiesterase-5 Enzyme Inhibitors Antidepressants, SSRIs Endothelin Antagonists ARBs Local Anesthetics, Amides Metabolic & Endocrine, Other Neuromuscular Blocker Agents, Botulinum Toxins Show All Questions & Answers Media Gallery References Overview Practice Essentials Raynaud phenomenon manifests as recurrent vasospasm of the fingers and toes and usually occurs in response to stress or cold exposure. [1] The phenomenon is named for Maurice Raynaud, who, as a medical student, defined the first case in 1862 as "episodic, symmetric, acral vasospasm characterized by pallor, cyanosis, suffusion, and a sense of fullness or tautness, which may be painful." [2] See the image below.

Secondary Raynaud phenomenon should be distinguished from primary Raynaud phenomenon (Raynaud disease). They are distinct disorders that share a similar name. Raynaud disease is characterized by the occurrence of the vasospasm alone, with no association with another illness. Secondary Raynaud phenomenon is a designation usually used in the context of vasospasm associated with a variety of rheumatologic and non-rheumatologic diseases, environmental exposures, and/or medications. [3]

Young women who have had Raynaud phenomenon alone for more than 2 years and have not developed any additional manifestations are at low risk for developing an autoimmune disease. The same should not be said for older patients and male patients with Raynaud phenomenon, as vasospastic symptoms may predate systemic disease by as many as 20 years. In some studies, 46%-81% of affected patients have secondary Raynaud phenomenon.

Although Raynaud phenomenon has been described with various autoimmune diseases, the most common association is with progressive systemic sclerosis (90% in individuals with scleroderma) and mixed connective-tissue disease (85% prevalence). Raynaud phenomenon has also been described with such diverse diseases as systemic lupus erythematosus and other disorders not classified as autoimmune, including frostbite, vibration injury, polyvinyl chloride exposure, and cryoglobulinemia.

For primary Raynaud phenomenon, the first line of therapy consists of lifestyle measures. If these prove inadequate, the patient may benefit from pharmacologic treatment. Therapy for secondary Raynaud phenomenon must be tailored to the underlying disorder. Patients with secondary Raynaud phenomenon are more likely to require pharmacologic therapy. A variety of drugs are used off-label for treatment; the most commonly used drug is nifedipine. See Treatment and Medication.

In individuals with Raynaud phenomenon, one or more body parts experience intense vasospasm with associated color change and subsequent hyperemia. Patients often describe 3 phases of change: initial white (vasoconstriction), followed by blue (cyanosis), and then red (rapid blood reflow). The affected body parts are usually those most susceptible to cold injury. A clear line of demarcation exists between the ischemic and unaffected areas (see the image below).

Primary Raynaud phenomenon is related to functional alterations alone. In contrast, secondary Raynaud phenomenon also reflects structural microvascular abnormalities. Herrick (2005) reviewed the pathogenesis of Raynaud phenomenon and describes the mechanisms under 3 categories: vascular, neural, and intravascular abnormalities. [5]

A deficiency of vasodilatory mediators, including nitric oxide, has been implicated in the pathogenesis of Raynaud phenomenon. [6] In addition, endothelin-1, a potent vasoconstrictor found in the endothelium, has been found to be circulating in high levels in patients with secondary Raynaud phenomenon. [6] Release of endothelin-1 is triggered by vasoactive stimuli, including angiotensin, vasopressin, and transforming growth factor-beta (TGF-beta) [7] Conflicting results regarding the levels of endothelin-1 in patients with primary Raynaud phenomenon are noted.

Edwards et al proposed that primary Raynaud's disease involves abnormal function of brain stem areas that integrate the cardiovascular components of the response to acute stress. These researchers found that initially, both patients with Raynaud phenomenon and healthy individuals responded to sound stimuli with vasodilation in forearm muscles and vasoconstriction in the skin of the digit. Over 5 days, however, healthy individuals showed habituation to the stimuli, while patients with primary Raynaud phenomenon did not. [11]

Enhanced vasoconstriction in Raynaud phenomenon may involve overactivity of α2C -adrenoreceptors; these adrenoreceptors have been found to enable cold-induced vasoconstriction of the blood vessels. [14] Two studies by Furspan et al showed that the enhanced contractile response to α2 -adrenergic agonists and cooling in patients with primary Raynaud phenomenon may be linked to increased protein tyrosine kinase activity. [15] These data suggest that protein tyrosine kinase inhibitors may be beneficial in the treatment of Raynaud phenomenon.

Rarely, secondary Raynaud phenomenon may be a paraneoplastic syndrome. Cases have been reported in patients with hematologic, lung, breast, uterine, and ovarian cancers, principally adenocarcinomas. [24]

A study using data from the population-based LifeLines Cohort Study from the Netherlands found an association between low body weight and prior involuntary weight loss and risk of Raynaud phenomenon in both men and women. The odds ratio (OR) for association of low body weight and Raynaud phenomenon was 5.55 in men (95% confidence interval [CI] 2.82-10.93) and 3.14 (CI 2.40-4.10) in women; the OR for association with involuntary weight loss was 1.32 (CI 1.17-1.48) in men and 1.31 (CI 1.20-1.44) in women. Low-fat diet was also associated with Reynaud phenomenon in women (OR 1.27, CI 1.15-1.44). [25]

A 7-year study of Raynaud phenomenon in whites in the United States showed baseline prevalence rates of 11% in women and 8% in men and yearly incidence rates of 2.2% in women and 1.5% in men. [26] Internationally, the prevalence of primary Raynaud phenomenon varies among different populations, from 4.9%-20.1% in women to 3.8%-13.5% in men. As in the United States, the prevalence of secondary Raynaud phenomenon depends on the underlying disorder. 781b155fdc