Sneddon syndrome is a slowly progressive disorder of small- and medium-sized arteries, which are the blood vessels that carry blood away from the heart. The disorder is characterized by blockages (occlusions) of the arteries that cause a reduction of blood flow to the brain and to the skin. Associated symptoms vary from one person to another based, in part, upon the specific arteries that are affected. An irregular, net-like pattern of bluish skin discoloration surrounding areas of normal-appearing skin (livedo reticularis) is characteristic of this disorder. The arms and legs are most often affected as well as the trunk, buttocks, and hands and feet. Livedo reticularis is worsened by cold and pregnancy. (In the European medical literature, the term livedo reticularis is used to describe the skin changes of the extremities only that disappear when the skin is warmed. Livedo racemosa is used to describe skin changes that involve also the buttocks and the trunk and do not disappear with warm temperatures. These two dermatologic conditions are separated because livedo reticularis is much more frequent, but the association with strokes exists for livedo racemosa only).
Generally, livedo reticularis develops before the neurological symptoms by as much as 10 years, although sometimes the onset of skin symptoms may occur at approximately the same time. Only rarely, do the skin symptoms occur after the neurological symptoms. Painfully cold fingers and toes caused by dilation or constriction of small vessels in response to cold (Raynaud’s phenomenon) may also occur. Blues discoloration of the hands and feet due to the lack of blood flow (acrocyanosis) has also been reported.
Recurrent episodes of mini-strokes (transient ischemic attacks) or strokes (cerebrovascular accidents) are a common finding of Sneddon syndrome. Less frequently, microbleeds and intracerebral hemorrhages also occur in Sneddon syndrome. The associated neurological symptoms vary depending upon the location of arterial blockages or bleedings. These symptoms may include difficulty concentrating, memory loss, Confusion, personality changes, impaired vision, and Weakness of one side of the body (hemiparesis). Sneddon syndrome may cause progressive reduction of mental and cognitive function, potentially resulting in dementia. Aphasia, which is defined as a communication disorder that impairs the ability to process language including impairing the ability to speak or understand others, is also common. Less often, Seizures, muscle pain and stiffness, and abnormal movements caused by repetitive, jerky muscle contractions (chorea) may also occur.
Generalized symptoms (e.g., Headaches and migraines and/or Dizziness or vertigo) may be present for several years before neurological symptoms and/or visible skin discoloration appears. High blood pressure (hypertension) is also common.
Heart murmurs, heart disease resulting from reduced blood flow to heart tissue (ischemic heart disease), or thickening of the valves between the chambers of the heart (valvular stenosis) have also been diagnosed in people with Sneddon syndrome and may be associated with rheumatic heart disease or endocarditis. In rare cases, impairment of the kidneys may occur.