Raynaud phenomenon: a cold-weather condition
A thorough work-up can differentiate between primary and secondary forms, mitigating progression of a more severe underlying disease.
As the colder months approach and the temperatures drop, Raynaud phenomenon (RP) will most likely be seen in an increasing number of patients in the primary care setting. RP is characterized by reversible bouts of digital vasospasm that are an exaggerated response to physical, chemical, or emotional stress.
The condition is primary in 80% of cases and secondary in 20%.1 The primary form is idiopathic—that is, not linked to any other comorbid condition or disease. The secondary form is diagnosed when an underlying condition is causing the symptoms of RP. The secondary form is most commonly caused by one of the autoimmune connective tissue diseases. The underlying disease is most frequently systemic sclerosis; RP is seen in 96% of patients with this condition.1 The secondary form can also be due to a vibration injury, medication, hematologic disorder, or an endocrine disorder.2 The differences between the two forms are imperceptible to the naked eye. Therefore, during the work-up of a patient with RP, laboratory studies are an important tool for differentiating between the primary and secondary forms.
The etiology and pathogenesis of RP have yet to be explained or understood completely, but several factors are thought to have a role. The average age of patients is 47.2 years in European countries and 53.5 years in the United States.1 In a randomized trial conducted in California that analyzed 162 patients with RP, 80.5% were found to be non-Hispanic whites, 0.6% were Native Americans/Alaskans, and 1.2% were Asian/Pacific Islanders.1 As for gender patterns within the United States, the prevalence is 9.6% in women and 5.8% in men.1 A heightened prevalence of RP has also been noted in male smokers and in women with a high rate of alcohol intake.1
Most clinicians can make the general diagnosis of RP by taking a history of the patient's symptoms. The more challenging aspect is deciding whether the symptoms are arising independently or because of another condition. In other words, does the patient have the primary or secondary form? A patient with RP will present with either a “triple” or “double” color change in the affected digits. The triple color change includes pallor (indicating ischemia), cyanosis (indicating deoxygenation), and erythema (indicating reperfusion); the double color change may present as pallor plus cyanosis or cyanosis plus erythema. The average length of a vasospastic episode is 20 minutes, but an episode has the potential to last for several hours. Symptoms typically subside with return to a warm room or placement of the affected body part in warm water. The patient may describe sensory changes such as numbness, decreased range of motion, decreased sensation, and aching pain.2 Numbness is most likely to coincide with ischemia, whereas pain is most likely to be associated with deoxygenation/cyanosis and reperfusion.3
Work-up of the patient with Raynaud phenomenon
It is imperative to determine whether a patient has primary RP or the secondary form with an underlying cause. Nailfold capillaroscopy and specific serologic testing are the most commonly used tools in the work-up of a patient with vasospastic attacks. The morphology of nailfold capillaries is examined by placing a drop of immersion oil onto the cuticle and viewing the region with a high-power magnification device.2 In a study of nailfold capillary patterns and connective tissue diseases among 67 patients with RP, Wu et al found that a patient with enlarged capillary loops or certain capillary patterns is likely to have a secondary form of RP.4 The capillary patterns differ depending on which autoimmune connective tissue disease affects the patient. Characteristics of various patterns, identified based on quantitative nailfold capillaroscopic observation, are listed in Table 1.5-8 Primary RP often exhibits a normal nailfold capillary pattern, which consists of a “parallel arrangement of hairpin-like capillaries in appropriate caliber and shape,” and therefore the diagnosis of secondary RP is excluded.4
Depending on a practitioner's ability to discern these characteristics, consistent findings on nailfold capillaroscopy make it possible not only to detect the presence of an underlying connective tissue disease but also to diagnose a specific connective tissue disease.4 Systemic sclerosis, systemic lupus erythematosus, polymyositis/dermatomyositis, and mixed connective tissue disease are all possible causes of RP and were the connective tissue diseases noted in this study. Within all the disease states, the study showed that nailfold capillaroscopy used for identifying a connective tissue disease is highly specific but is highly sensitive only for identifying systemic sclerosis and polymyositis/dermatomyositis. Therefore, nailfold capillaroscopy has potential value as a diagnostic tool in secondary RP. However, careful training and considerable practice at identifying these capillary patterns are needed, which may be unrealistic goals for primary care practitioners dealing with a disease that has a prevalence of only approximately 10% in women and 6% in men in the United States.1