Syndrome de Sneddon

Synonym: Ehrmann-Sneddon syndrome

What is Sneddon's syndrome?

Sneddon's syndrome is a non-inflammatory arteriopathy in which livedo reticularis is associated with cerebrovascular disease.¹ It is slowly progressive and may go undiagnosed for some time.² It may be seen in patients with an autoimmune disorder - eg, syndrome des antiphospholipides ou lupus érythémateux systémique (LES).

• It has been estimated that the incidence is 4 per 1 million per annum and generally occurs in women between the ages of 20 and 42 years.³

• Although initially thought to have a genetic aetiology (one family cluster displayed autosomal dominant inheritance), further studies have failed to demonstrate any family history in most affected patients.¹

• Sneddon's syndrome develops slowly over a variable timeframe.

• Livedo reticularis may precede the onset of stroke by years and the trunk and/or buttocks are involved in nearly all patients. The cerebrovascular manifestations are mostly secondary to ischaemia (transient ischemic attacks et cerebral infarction).

• Other neurological symptoms range from headache, cerebral haemorrhage, seizures, as well as cognitive and psychiatric disturbances.

• Involvement of fundi, peripheral nerves, heart, and kidneys is frequent but usually asymptomatic.

• Livedo reticularis is a bluish mottling of skin, usually on the legs, and the appearance may be aggravated by exposure to cold.⁴

• Sneddon's syndrome has been classified as primary if there is no clear cause, or secondary where it occurs as part of an autoimmune disorder (eg, périartérite noueuse, SLE, syndrome des antiphospholipides), or in a thrombophilic state (eg, thrombocythaemia).^{5 6}

• Other associations include hypertension, systemic ischaemia (including ischaemic heart disease), heart valve lesions and venous thrombosis.

• Antiphospholipid antibodies have been found in 80% of patients with Sneddon's syndrome.⁷

• Neuroimaging, including MRI, histological, immunohistochemical and ultrasound evaluation may be useful for diagnosis.⁸

• Histological findings of skin biopsies are characteristic and the involved vessels are small to medium-sized arteries at the border of dermis.³

• The optimal management remains uncertain. Long-term anticoagulation has been recommended for cerebral ischaemic events.³

• In patients without any prior history of thromboembolism, minimise risk factors (stop smoking and/or combined oral contraceptives, control any hypertension, and treat any hyperlipidaemia).

• Consider prophylaxis with low-dose aspirin (clopidogrel if unable to take aspirin), particularly in patients with antiphospholipid or antiprothrombin antibodies. It may be appropriate for all patients but more research is needed.

• Patients with a history of thrombosis are treated indefinitely with anticoagulation (with warfarin ± low-dose aspirin).

• Immunosuppressive agents are used in some cases chronically resistant to anticoagulation treatment.

• Some symptoms tend to resolve over a very variable time course.

• Prevention of further vascular events with anticoagulation is the key to a good prognosis.