Maurice Raynaud in 1862 described RP, which is a vasospastic disorder characterized by episodic attacks of well-demarcated color changes with numbness and pain of the digits on exposure to cold. It may be primary (idiopathic) or secondary to an underlying condition.
- Vasopasm of the digital arteries and cutaneous arterioles causes Raynaud’s phenomenon (RP)
- The sequential color changes of RP are white to blue to red.
- Nailfold capillary microscopy and specific autoantibodies predict which patients with RP are likely to develop a rheumatic disorder.
Conditions associated with secondary RP may be grouped into seven broad categories: systemic, traumatic (vibration) injury,drugs or chemicals, occlusive arterial disease, hyperviscosity syndromes, endocrine disorders, and miscellaneous causes
Primary RP: increased sensitivity to cold temperatures is attributable to a defect causing an increase in α-2 adrenergic responses in the digital and cutaneous vessels. Notably the blood vessel is structurally normal.
Secondary RP: the underlying vascular disease disrupts the normal mechanisms responsible for control of vessel reactivity.
The sequential color changes of RP are white to blue to red. Initial digital artery vasospasm causes a pallor (blanching) of the digit which gives way to cyanosis as static venous blood deoxygenates. With rewarming, the ischemic phase lasts 15 to 20 minutes followed by reactive hyperemia which causes the final stage, rubor. The classic triad in the classic order may not be seen in all patients. Pallor is the most definitive phase.