Raynaud's phenomenon or, simply, Raynaud's, is a disorder characterized by decreased blood flow - usually to the fingers, and less frequently to the ears, toes, nipples, knees, or nose. Dr. Edwin Smith, a rheumatology and immunology specialist defines Raynaud's Phenomenon and discusses the symptoms such as pain and numbness. Dr. Smith also talks about treatment options; one important treatment is to simply stay warm to avoid cold exposure.