Clinical manifestations and diagnosis of Raynaud phenomenon

INTRODUCTION — Raynaud phenomenon (RP) is an exaggerated vascular response to cold temperature or emotional stress. The phenomenon is manifested clinically by sharply demarcated color changes of the skin of the digits. The underlying problem is thought to be abnormal vasoconstriction of digital arteries and cutaneous arterioles due to a local defect in normal vascular responses.

RP is considered primary if these symptoms occur alone without evidence of any associated disorder. By comparison, secondary RP refers to the presence of the disorder in association with a related illness, such as systemic lupus erythematosus (SLE) and systemic sclerosis (SSc; scleroderma).

The clinical manifestations and diagnosis of RP are reviewed here. The pathogenesis and treatment of this disorder are presented separately. (See "Pathogenesis and pathophysiology of Raynaud phenomenon" and "Treatment of Raynaud phenomenon: Initial management" and "Treatment of Raynaud phenomenon: Refractory or progressive ischemia".)

TERMINOLOGY

Primary versus secondary Raynaud phenomenon — Patients with Raynaud phenomenon (RP) are described as having either a primary or secondary process.

●Primary RP – Primary RP or idiopathic Raynaud disease are terms to describe manifestations in patients without evidence of any associated disorder as a cause for their vascular events. Most investigators feel the term "disease" is inappropriate and prefer using the term primary RP for otherwise healthy individuals. In this setting, RP is considered to be an exaggeration of normal vasoconstriction to cold exposure. (See "Pathogenesis and pathophysiology of Raynaud phenomenon".)

Primary RP usually has an age of onset between 15 and 30 years, is more common in females, and may occur in multiple related family members [1]. Although patients with primary RP are generally otherwise healthy, comorbid conditions can occur that may aggravate attacks. These include hypertension, atherosclerosis, cardiovascular disease, and diabetes mellitus. A meta-analysis of observational studies found that risk factors for primary RP included female sex, family history, smoking, manual occupation, migraine, and cardiovascular disease [2]. While nicotine exposure by smoking decreases cutaneous blood flow, the impact of chronic smoking on RP is not well defined [3,4].

There are conditions that appear to be associated with RP, but it is unclear if they are pathologically linked like the various causes of secondary RP. As an example, there is reportedly an increase in prevalence of RP among patients with fibromyalgia [5,6]. However, these reviews may have included subjects with secondary disease states. One study found that while patients with fibromyalgia have self-reported symptoms consistent with RP, direct testing found no association between skin temperature and digital color changes in patients with fibromyalgia, suggesting a different etiology than RP for skin changes in fibromyalgia [5-9].

Similarly, there are several reviews that support an association of migraine headaches with RP [10-13]. It is not established that RP and migraine headache share a common cause or mechanism of vascular dysfunction. However, in spite of this, there remains an association of RP with migraine [11,13-17]. (See "Pathophysiology, clinical manifestations, and diagnosis of migraine in adults".)

●Secondary RP – Secondary RP manifests in patients who have an associated disease that may underlie the episodes. Some clinicians prefer the term Raynaud syndrome.

A variety of mechanisms can disrupt the normal regulation of regional blood flow to the digits and skin, and thus, the number of diseases and exposures associated with secondary RP is extensive:

•Diseases commonly associated with RP include autoimmune rheumatic diseases such as systemic sclerosis (SSc; scleroderma), systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), Sjögren's syndrome, and dermatomyositis/polymyositis.

•Various drugs or toxins can also precipitate or exacerbate RP such as amphetamines and chemotherapeutic agents (especially cisplatin and bleomycin) [18].

•Hematologic abnormalities associated with RP include cryoglobulinemia, cold agglutinin disease, paraproteinemia, POEMS (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal protein, Skin changes) syndrome, and cryofibrinogenemia.

•Occupational and environmental causes of RP include vascular trauma (eg, injury to the distal ulnar artery in hypothenar hammer syndrome) [19-23], the use of tools that vibrate [24-27], frostbite [28], and carpal tunnel syndrome [29].

•Hypothyroidism may predispose to RP, and improvement of cold-induced vasospasm may occur with thyroid hormone replacement.

It is important to distinguish occlusive vascular disease from the reversible events of RP. For example, inflammatory vascular disease or vasculitis may cause a blue cold finger and ischemic lesions due to irreversible loss of cutaneous blood flow. Diseases with occlusive vascular disease may also be associated with true RP. For example, RP is an early manifestation in up to 40 percent of patients with thromboangiitis obliterans (ie, Buerger's disease).

Since primary RP is common in the general population, some of the reported associations of RP have remained unproven. As an example, the prevalence of RP in rheumatoid arthritis is controversial. Some surveys suggest no increase in risk [30,31], but other studies have found that 17 to 22 percent of patients with rheumatoid arthritis had RP [32,33]. Those with RP were more likely to have vasculitis or severe disease [32,33].

EPIDEMIOLOGY — Establishing the true prevalence of Raynaud phenomenon (RP) is hampered by the lack of a well-defined reproducible "gold standard" diagnostic test. Cold hands and feet are a normal physiologic response to cold exposure that, to preserve heat, cools the surface skin and causes skin color changes, whereas RP is an exaggerated vascular response to cold temperature or emotional stress. Although survey criteria vary, most investigators agree that a history of at least two color changes (pallor and cyanosis) after cold exposure is necessary for a definite diagnosis.

Community-based surveys have been performed to estimate the prevalence of RP in the general population. In these surveys, estimates of the prevalence of RP have ranged from 3 to 20 percent in females and 3 to 14 percent in males.

These relatively wide ranges reflect, in part, the populations that are studied [16,17,34-41]:

●RP is more common in France (17 percent) than in the United States (5 percent) [34].

●A survey performed by the author in an African American community found a prevalence of 3 percent [38].

●As reported in a community survey of 1525 participants, the prevalence of primary RP was approximately 11 and 9 percent in females and males, respectively [39].

RP is more common among young females, younger age groups, and related family members of patients with RP [1,2,10,12]. There are few studies of RP in children [40-43]. RP often starts early in life, but the prevalence then appears to remain relatively constant throughout life [44]. A review found a 0.1 to 1 percent prevalence of new-onset RP among individuals over the age of 60 years [45]. A survey reported that low body weight was associated with an increased risk of RP in males and females [46]. Additionally, the prevalence of RP found in a given population is influenced by the climate of the region studied [47].

The true prevalence of RP in children is challenging to define due to the lack of good definition of cases. It is estimated that approximately 70 percent of childhood-onset RP is primary RP, while secondary RP cases are often related to autoimmune disease [48,49].

The reported frequencies and rates of development of a disease or disorder to which RP is secondary among patients initially thought to have primary RP vary. A meta-analysis of 10 articles including approximately 640 patients diagnosed with primary RP found that 81 patients (13 percent) eventually developed an autoimmune rheumatic disease [50]. In a longitudinal study including 307 patients with RP, the annual incidence of transition from presumed primary RP to secondary RP was 1 percent [51]. Other large cohorts of patients with an initial presentation suggesting primary RP reported that between 16 and 37 percent transition to secondary RP during the follow-up period [52,53].

CLINICAL FEATURES — Both primary and secondary Raynaud phenomenon (RP) most often affect the digits (ie, fingers, toes) [54-57]. Cutaneous vasospasm is also common at other sites, including the skin of the ears, nose, face, knees, and nipples. (See "Common problems of breastfeeding and weaning", section on 'Nipple vasoconstriction'.)

A Raynaud attack typically begins in a single finger and then spreads to other digits symmetrically in both hands. The index, middle, and ring finger are the most frequently involved digits, while the thumb is often spared entirely (particularly in primary RP) [58]. Involvement of the thumb may indicate a secondary cause of RP [59].

Signs and symptoms of Raynaud phenomenon

●Digital color changes – With both primary and secondary RP, a typical episode is characterized by the sudden onset of cold fingers (or toes) in association with sharply demarcated color changes of skin pallor (white attack) due to constricted blood flow, followed by cyanotic skin (blue attack), which indicates tissue hypoxia (picture 1). With rewarming, the ischemic phase (white or blue attack) usually lasts for 15 to 20 minutes. The skin subsequently blushes upon recovery, thereby resulting in the erythema of reperfusion. The presence of self-reported or witnessed blue and white color changes are generally required for establishing the diagnosis. In patients with highly pigmented skin, the cutaneous changes may be more visible on the palmar surface of the fingers. (See 'Presumptive diagnosis' below.)

Cold-induced skin color changes reflect the reversible vasospastic aspects of RP. However, more persistent digital vascular compromise (eg, persistent cyanosis without blanching) secondary to the irreversible and often progressive obliterative microangiopathy also contributes to digital vascular symptoms in systemic sclerosis (SSc; scleroderma). Patients with RP associated with SSc can experience digital color changes that persist between isolated RP events [60]. (See "Clinical manifestations and diagnosis of systemic sclerosis (scleroderma) in adults", section on 'Digital vasculopathy'.)

●Symptoms of digital ischemia – The symptoms of RP may include pain resulting from low blood flow or ischemia. Ischemia can be transient or prolonged, with complete recovery or with varying levels of tissue injury. Acute ischemia refers to sudden compromise of nutritional blood lasting a short period of time, whereas chronic ischemia refers to a prolonged compromise to nutritional flow. (See "Overview of upper extremity ischemia", section on 'Acute ischemia' and "Overview of upper extremity ischemia", section on 'Chronic ischemia'.)

As an example, an episode of acute ischemia may be mild and associated with sensations of pins and needles, numbness and/or clumsiness of the fingers, and finger pain or aching. The signs of mild RP should be completely reversible on rewarming or reduction of stress. Less severe disease is most commonly observed in those with primary RP. More persistent symptoms of digital vascular compromise in SSc appear to be associated with longer disease duration and may reflect progression of the underlying obliterative microangiopathy.

Mild to severe ischemia can be observed in patients with secondary RP. As an example, with severe RP secondary to SSc, tissue loss (ulceration or gangrene typically located on the tips of the fingers) may result from severely reduced digital perfusion. (See "Overview of upper extremity ischemia", section on 'Chronic ischemia' and "Clinical manifestations and diagnosis of systemic sclerosis (scleroderma) in adults", section on 'Digital vasculopathy'.)

●Livedo reticularis – During a cold response, patients with RP may also exhibit livedo reticularis; this is a violaceous mottling or reticular pattern of the skin of the arms and legs, sometimes with regular unbroken circles [61]. This finding is benign and completely reversible with rewarming. (See "Approach to the patient with retiform (angulated) purpura".)

By comparison, nonreversible skin changes may be observed in patients with vasculitis, occlusive vascular disease (eg, due to atheroemboli or thrombosis), or antiphospholipid syndrome (APS). These cutaneous changes may also be associated with irregular broken circles. Due to these differences, some experts advocate use of the term "livedo racemosa" rather than "livedo reticularis" for these cutaneous findings in patients with inflammatory or thrombotic vascular disease [62]. (See "Clinical manifestations of antiphospholipid syndrome" and "Overview of cutaneous lupus erythematosus".)

Precipitating factors — Patients with both primary and secondary RP note that exposure to cold temperature triggers RP. More importantly, the provocation occurs during relative shifts from warmer to cooler temperatures. As a result, mild cold exposures such as air conditioning or the cold of the refrigerated food section of the grocery store may cause an attack. Although attacks occur locally in the fingers, a general body chill will also trigger an episode, even if the hands or feet areas are kept warm.

An attack of RP may also occur after stimulation of the sympathetic nervous system (such as emotional stress, sudden startling). It is not uncommon for the clinician to witness a typical attack during the first encounter with a frightened or nervous patient.

DIAGNOSTIC EVALUATION

Presumptive diagnosis — There are no simple office tests or other standard diagnostic criteria that can be used to diagnose RP. The evaluation of RP is initiated by asking the patient the following questions:

●Are your fingers unusually sensitive to cold?

●Do your fingers change color when exposed to cold?

●If the fingers change color, do they turn white, blue/purple, or both?

The patient's response to these questions can help make a presumptive diagnosis of RP [54,57]. This simple approach (algorithm 1) is generally consistent with various other proposed systems that generally rely on self-reporting and focus on an episodic paradigm of RP requiring cold sensitivity along with vasospastic events manifesting as digital color changes [63-66]. In addition to color changes, symptoms may include paresthesias and numbness with cold exposure. Attempts to induce an attack, such as with a cold-water challenge, are not recommended since the responses are inconsistent even in those with definite RP.

In addition to evaluating the patient for possible conditions associated with secondary RP, they should be evaluated for conditions that may appear like RP. (See 'Differential diagnosis' below.)

Further evaluation — Although extensive special testing is not always necessary, every patient with a presumptive diagnosis of RP should be carefully evaluated to identify clinical symptoms or signs indicative of a secondary disorder. This is accomplished initially with a careful history and physical examination.

The history should include the age of onset of the skin color changes, the involved digits, degree of symmetry and severity of the attacks, and any history of digital tissue loss. The physical examination should identify areas of tissue loss (eg, ulceration, gangrene) typically affecting the fingers or toes. Other sites that may be affected by cutaneous vasospasm should also be examined closely, including the skin of the ears, nose, face, knees, and nipples. A complete physical exam should also include a thorough musculoskeletal and cardiopulmonary evaluation, as possible clues that any underlying systemic rheumatic disease may be present. Peripheral pulses should be assessed for evidence of proximal (large) vessel disease.

Patients should also be asked questions about symptoms that may be suggestive of a systemic rheumatic disease (eg, systemic sclerosis [SSc; scleroderma] or systemic lupus erythematosus [SLE]) such as:

●Fever

●Arthralgia/arthritis

●Myalgias

●Dysphagia, gastroesophageal reflux

●Skin thickening, sclerodactyly

●Cardiopulmonary abnormalities

Patients should also be asked about potential exposures or aggravating factors including:

●Occupational and environmental factors – The patient should be asked about exposure to polyvinyl chloride, occupational or recreational cold exposure (eg, history of frostbite), exposure to excessive vibration (eg, jack hammer operator), repetitive hand trauma (carpenter, blacksmith), and history of carpal tunnel syndrome.

●Medications or toxins – The patient should be questioned about recreational and prescription drugs including chemotherapeutic agents (especially cisplatin or bleomycin) [18], interferon [67], estrogen, sympathomimetic agents, ergotamines, clonidine, nicotine, and narcotics. There are case reports of aggravation of RP after use of calcitonin gene-related peptide (CGRP) antagonists used to treat migraine headaches [68].

Nailfold capillary microscopy — Nailfold capillaroscopy is a common method to help distinguish patients with primary RP from those with secondary RP and is typically performed by a rheumatologist or dermatologist.

Nailfold capillary microscopy is accomplished by dropping oil on the periungual area and examining with an ophthalmoscope set at diopter 40 or with a dissecting microscope. A specialized handheld dermatoscope that magnifies a view of the area is also available. High-magnification nailfold videocapillaroscopy is used in some specialty centers [69]. Enlarged or distorted capillary loops and/or dropout or loss of loops suggest an underlying (or an increased likelihood of developing) systemic rheumatic disease [50,70-73]. If the enlargement is associated with loss of capillaries, then the patient is more likely to have or develop SSc (picture 2) [71,74-76]. Abnormal nailfold capillaries also can be seen in nonrheumatic disorders associated with microvascular disease [77]. Standardization of the interpretation of nailfold capillaries microscopy enhances the ability to distinguish normal from abnormal capillaries, and the features of SSc from other diseases [78] (See "Clinical manifestations and diagnosis of systemic sclerosis (scleroderma) in adults".)

Limited role of other tools — Other techniques to assess the vascular responses in the digits and skin are also available, but they are typically used in specialty centers or for research purposes. These tools include thermography, angiography, laser Doppler imaging, and direct measures of skin temperature and local blood flow [79,80]. Nailfold capillaroscopy, thermal imaging, and laser Doppler imaging each independently provide good discrimination between healthy controls and primary RP [81]. The response of the digital systolic blood pressure to cooling is associated with the RP attack frequency and has been used in clinical trials as a measure of RP severity [82,83]. Blood perfusion measured by laser speckle contrast imaging can distinguish patients with RP from those without, but is not widely available [84,85]. These laboratory-based tools are useful for studying the physiology of RP but may not predict response to therapy or the severity of RP in an ambulatory setting.

Diagnosing secondary versus primary Raynaud phenomenon — Our approach to evaluating for secondary RP is summarized in an algorithm (algorithm 2).

●Secondary RP – We diagnose secondary RP if the results of a thorough history and physical examination, including nailfold capillary microscopy, suggest an underlying cause for RP.

Other clinical features associated with a moderate or higher clinical suspicion of a secondary cause of RP include the following [52,53,86-91]:

•Later age of onset (greater than 40 years)

•History of a known precipitant

•Male sex

•Painful severe events with tissue sign of ischemia (ulceration)

•Asymmetric attacks

•RP associated with signs or symptoms of another disease

•Abnormal nailfold capillaries

•Abnormal laboratory parameters suggesting vascular disease or an autoimmune disorder

•RP associated with ischemic signs or symptoms proximal to the fingers (such as the hand or arm) or toes (foot or limb)

•Presence of autoantibodies

●Primary RP – We diagnose primary RP in a patient if the history and physical examination does not suggest a secondary cause for RP, even if nailfold capillary microscopy cannot be performed. Clinical features associated with primary RP include the following [63,92]:

•Vasospastic attack precipitated by cold or emotional stress

•Bilateral symmetric attacks

•No tissue necrosis or gangrene

•No history or physical findings suggestive of secondary cause of RP

•Normal nailfold capillaries

•Normal erythrocyte sedimentation rate (ESR)

•Absence of autoantibodies

Nailfold capillary studies are ideal, but skills to do such an assessment may not be readily available to the primary care clinician. If other features point away from a secondary autoimmune disease, nailfold capillary assessment is not required. If felt to be necessary, referral for nailfold capillary microscopy (typically performed by a rheumatologist or dermatologist) would only be recommended if there is a clinical suspicion of a secondary RP or autoimmune disease.

Among patients with probable primary RP, there is no need for further specialized laboratory testing. However, we recognize that serologic testing such as antinuclear antibody (ANA) is often done in this clinical setting. A weakly positive ANA (<1/160) is common in the general population; therefore, a positive test must be interpreted in the context of the entire clinical situation. (See "Measurement and clinical significance of antinuclear antibodies".)

The key is careful serial follow-up of patients with probable primary RP to confirm the clinical diagnosis. Periodic follow-up is necessary to ensure that signs and/or symptoms of secondary causes of RP do not emerge. Most studies find that a transition to a defined secondary systemic rheumatic disease usually occurs within two to five years of presentation with RP; however, the interval may be more prolonged [50].

Laboratory testing for secondary Raynaud phenomenon — If the clinical evaluation defines features consistent with primary RP, then additional diagnostic testing specific for RP is generally not necessary. However, we monitor the patient annually (or sooner) for the development of signs and symptoms of diseases associated with secondary RP.

Patients with a suspicion of a diagnosis of secondary RP, with or without abnormal nailfold capillaries, should undergo additional testing. The exact laboratory tests should be guided by the clinical findings from the history and physical examination. (See 'Further evaluation' above.)

We generally obtain the following laboratory tests in most patients with newly diagnosed secondary RP:

●Complete blood count and differential

●Complete metabolic panel

●Urinalysis with urine sediment

●ANA (ideally by indirect immunofluorescence testing)

●Thyroid-stimulating hormone (TSH)

●ESR and/or C-reactive protein (CRP) levels

Additional laboratory tests may be warranted depending on the presence of other clinical symptoms. As examples:

●For patients with sclerodactyly and digital ulcers, antibodies specific for SSc such as antitopoisomerase I (anti-Scl-70), anticentromere, and anti-RNA polymerase III should be obtained. (See "Clinical manifestations and diagnosis of systemic sclerosis (scleroderma) in adults", section on 'Laboratory testing'.)

●For patents with suspected inflammatory myopathy, creatinine kinase and possibly other myositis-specific autoantibodies (eg, anti-Jo-1) should be obtained. (See "Overview of and approach to the idiopathic inflammatory myopathies", section on 'Laboratory findings'.)

●For patients with suspected SLE or cryoglobulinemia, serum C3 and C4 complement levels should be obtained. (See "Clinical manifestations and diagnosis of systemic lupus erythematosus in adults", section on 'Laboratory testing'.)

●For patients with a suspected paraproteinemia, serum protein electrophoresis (SPEP) should be obtained.

Vascular imaging for atypical attacks — Patients who have a history of single-digit or asymmetric attacks, absent pulses, asymmetric blood pressure, or evidence of chronic ischemia should undergo vascular imaging to evaluate for conditions causing large vessel occlusive disease (eg, subclavian stenosis), medium vessel obstruction (eg, thromboembolic debris, medial calcification), or small vessel disease (eg, thromboangiitis obliterans). The selection of vascular imaging (eg, arterial duplex ultrasonography, computed tomographic [CT] or magnetic resonance [MR] angiography, or digital subtraction angiography) depends on the features of the clinical presentation. (See "Overview of upper extremity ischemia", section on 'Vascular imaging'.)

DIFFERENTIAL DIAGNOSIS — Conditions that can cause upper extremity, including hand, ischemia, are reviewed separately. (See "Overview of upper extremity ischemia".)

There are several conditions and disorders that can mimic Raynaud phenomenon (RP):

●Excessive cold sensitivity – Many individuals report excessive cold sensitivity of cold hands and feet when they are exposed to a cold environment, but they do not see skin color changes. In one study, 10 percent of those surveyed had cold sensitivity [93]. This common complaint of cold hands and feet may be a familial trait [94]. Cold sensitivity and decreased skin blood flow following cold exposure occurs more commonly in females and in the older population [95].

●External compression of blood vessels – External compression of blood vessels (eg, carrying a heavy parcel) can cause a transient decrease in blood flow, and, as a consequence, a hand and fingers can be temporally numb, pale, and/or cold. Unlike RP, this is not induced by cold or stress and is easily reversed once blood flow is restored.

●Peripheral neuropathy – Peripheral neuropathy can cause cold intolerance with numbness and skin color changes in the hands and feet [96,97]. However, unlike those with RP, patients with peripheral neuropathy may also have distal loss of sensation to pin prick, light touch, cold, and proprioception. (See "Overview of lower extremity peripheral nerve syndromes" and "Overview of upper extremity peripheral nerve syndromes".)

●Complex regional pain syndrome – Complex regional pain syndrome (CRPS) is a disorder of a body region, usually the extremities, characterized by pain, paresthesia, vasomotor instability, and altered skin temperature [98]. Although patients with CRPS may have vasomotor disturbances that can produce altered color and temperature, this is typically followed by muscle wasting, which is not observed in primary RP, and the pain is usually continuous (in RP, pain is intermittent). (See "Complex regional pain syndrome in adults: Pathogenesis, clinical manifestations, and diagnosis".)

●Occlusive vascular disease – Occlusive vascular disease (eg, emboli, thrombosis, atherosclerosis, thromboangiitis obliterans) can cause a cold limb, if acute occlusion occurs in a large vessel, or cause hand, foot, or digit ischemia, which may be associated with secondary vasospasm. Unlike typical RP, symptoms related to occlusive vascular disease are often asymmetric and when the hand is involved, are often limited to a single digit; vasospasm may be present with chronic ischemia but with complete vascular occlusion, may be irreversible and nonresponsive to vasodilator therapy. Vascular imaging will be needed to identify the occlusive lesion. (See "Clinical features and diagnosis of lower extremity peripheral artery disease" and "Overview of upper extremity ischemia" and "Embolism to the upper extremities" and "Embolism to the lower extremities" and "Thromboangiitis obliterans (Buerger disease)".)

●Acrocyanosis – Acrocyanosis is a functional peripheral vascular disorder characterized by symmetrical painless and persistent blue discoloration of the hands or feet, which is often aggravated by cold exposure [99]. Acrocyanosis can be differentiated from RP by the relative persistence of skin color changes, symmetry, and absence of paroxysmal pallor. As with RP, acrocyanosis is aggravated by cold exposure; however, it is also often associated with hyperhidrosis of hands and feet. RP attacks superimposed on acrocyanosis are not uncommon, and it may be difficult to distinguish the two disorders. Unlike RP, acrocyanosis rarely responds to vasodilator therapy.

●Pernio (chilblains) – Pernio is an inflammatory cutaneous condition involving localized swelling and erythema caused by exposure to cold and damp conditions. Areas typically involved include the hands, feet, ears, and face. Unlike RP, in which the skin changes are transient, in patients with pernio there are papules, plaques, and nodular lesions. RP and acrocyanosis can also coexist with pernio. (See "Pernio (chilblains)".)

●Acute idiopathic blue finger – Acute idiopathic blue finger, also known as Achenbach syndrome or paroxysmal finger hematoma, is a rarely reported clinical disorder in which patients present with sudden onset of painful swelling of at least one digit, with an ecchymosis-like discoloration developing on the volar aspect of the finger [100-103]. The blue discoloration usually spares the distal segment of the finger. The clinical course is benign, and symptoms typically resolve without lasting sequelae.

●Erythromelalgia – Erythromelalgia (EM) is an exaggerated blushing of the skin that can mimic the recovery phase or hyperemic phase of RP [104]. In contrast to RP, the vasodilatation associated with EM is triggered by warm temperature and is improved with cold exposure. In some cases, RP and EM may coexist [105]. (See "Erythromelalgia".)

●Paraneoplastic acral vascular syndrome – Paraneoplastic acral vascular syndrome is a rare vascular disease associated with malignancy [106]. Patients present with manifestations of digital ischemia, including RP, acrocyanosis, and digital gangrene.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Raynaud phenomenon".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Raynaud phenomenon (The Basics)")

●Beyond the Basics topics (see "Patient education: Raynaud phenomenon (Beyond the Basics)")

SUMMARY

●Raynaud phenomenon – Raynaud phenomenon (RP) is an exaggerated vascular response to cold temperature or emotional stress. The phenomenon is manifested clinically by sharply demarcated color changes of the skin of the digits (ie, fingers, toes). The underlying problem is thought to be abnormal vasoconstriction of digital arteries and cutaneous arterioles due to a local defect in normal vascular responses. RP is more common among young females, younger age groups, and related family members of patients with RP. (See 'Introduction' above and 'Epidemiology' above.)

●Primary versus secondary RP – Patients with RP are described as having either a primary or secondary process (see 'Primary versus secondary Raynaud phenomenon' above):

•Primary RP – Primary RP or idiopathic Raynaud disease are terms used to describe manifestations in patients without evidence of any associated disorder as a cause for their vascular events.

•Secondary RP – Secondary RP manifests in patients who have an associated disease that may underlie the episodes.

●Signs and symptoms – With both primary and secondary RP, a typical episode is characterized by the sudden onset of cold fingers (or toes), often precipitated by exposure to cold surfaces or ambient temperature shifts. The episode occurs in association with sharply demarcated color changes of skin pallor (white attack) due to constricted blood flow, followed by cyanotic skin (blue attack), which indicates tissue hypoxia (picture 1). With rewarming, the ischemic phase (white or blue attack) resolves. Ischemia can be transient, 15 to 20 minutes, or more prolonged. The skin subsequently blushes upon recovery, thereby resulting in the erythema of reperfusion. In patients with highly pigmented skin, the cutaneous changes may be more visible on the palmar surface of the fingers. (See 'Clinical features' above.)

●Presumptive diagnosis – There are no simple office tests or other standard diagnostic criteria that can be used to diagnose RP. The evaluation of RP is initiated by asking the patient the following questions (see 'Presumptive diagnosis' above):

•Are your fingers unusually sensitive to cold?

•Do your fingers change color when exposed to cold?

•If the fingers change color, do they turn white, blue/purple, or both?

The patient's response to these questions help make a presumptive diagnosis of RP. Our diagnostic approach is summarized in an algorithm (algorithm 1).

●Evaluation – Special testing is not always necessary, but every patient with a presumptive diagnosis of RP should be carefully evaluated to identify clinical symptoms or signs indicative of a secondary disorder, with a careful history and physical examination looking for clinical features suggestive of a systemic rheumatic disease (eg, systemic sclerosis [SSc; scleroderma] or systemic lupus erythematosus [SLE]) and to identify potential exposures or aggravating factors (eg, certain occupational and environmental factors, medications, and toxins). Patients with atypical attacks should undergo vascular imaging to evaluate for other conditions. (See 'Diagnostic evaluation' above.)

●Diagnosing secondary versus primary RP – Our approach to evaluating for secondary RP is summarized in an algorithm (algorithm 2). We diagnose secondary RP if the results of a thorough history and physical examination, including nailfold capillary microscopy, suggest underlying cause for RP. In the absence of an identified underlying cause, a diagnosis of primary RP can be made, even if nailfold capillary microscopy cannot be performed. However, for some patients, a secondary cause may manifest later on; these patients should be followed clinically. (See 'Diagnosing secondary versus primary Raynaud phenomenon' above.)

●Differential diagnosis – There are several conditions and disorders that can mimic RP. These include excessive cold sensitivity, external compression of blood vessels, peripheral neuropathy, complex regional pain syndrome (CRPS), occlusive vascular disease, acrocyanosis, pernio (chilblains), acute idiopathic blue finger, erythromelalgia (EM), and paraneoplastic acral vascular syndrome. (See 'Differential diagnosis' above.)