What are the etiologies of systemic lupus erythematosus (SLE), in relation to CNS lupus?

Updated: May 04, 2021
  • Author: Pradeep C Bollu, MD; Chief Editor: Niranjan N Singh, MBBS, MD, DM, FAHS, FAANEM  more...
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Answer

Among the neurologic manifestations of systemic lupus erythematosus (SLE), the most common are the organic encephalopathies. These diffuse syndromes correlate poorly with the extent of vasculitis or frank thromboembolism. Functional studies such as positron emission tomography (PET) scanning, functional magnetic resonance imaging (MRI), or single photon emission computerized tomography (SPECT) scanning demonstrate patchy areas of dysfunction in brain areas not demonstrable on conventional MRI, findings that suggest an uncoupling of metabolic processes independent of obstruction to cerebral blood flow. The mechanism of these apparent metabolic alterations is unknown. (See CT Scanning and MRI.)

In areas of apparent vasculitis, histology demonstrates degenerative changes in small vessel walls, often with minimal or no inflammatory infiltrates. Chronic effects of immune complex deposition offer one potential mechanism for SLE vasculopathy; cytokine-mediated effects on vascular endothelium or local brain parenchyma are another. Inflammatory and noninflammatory SLE vasculopathies may be clinically indistinguishable. The terms cerebritis and vasculitis are well embedded in the literature and will be used in this article, keeping in mind the evolving understanding of the underlying processes.

In addition to small vessel vasculopathy, inflammatory changes may occur in large- to medium-sized vessels, giving a more classic vasculitis, sometimes with clinical stroke syndromes resulting from local thrombosis or artery-to-artery emboli. Other potential stroke etiologies include local thrombosis from antiphospholipid antibodies, which may involve small or medium-sized arteries or veins, including the venous sinuses.

Emboli can occur as a result of Libman-Sacks endocarditis (LSE), a sterile endocardial inflammation that produces vegetations on the heart valves, seen in greater frequency in the presence of antiphospholipid antibodies. LSE may also cause a diffuse microembolization pattern that is clinically hard to distinguish from vasculitis or cerebritis. In focal clinical syndromes, overt or covert cardiac emboli are more frequently responsible than focal vasculitic or thrombotic processes. (See Biopsies and Histologic Features.)

Antiphospholipid antibodies comprise one category of the multiple autoantibodies that may be associated with SLE. In addition to their association with LSE and local arterial or venous thrombosis, these antibodies also may be associated with a hemorrhagic diathesis, myelopathy, and non-neurologic manifestations such as spontaneous abortion.

Dural sinus thrombosis is a rare complication of SLE-associated hypercoagulability and is often seen in association with antiphospholipid antibodies. Radiologically, flow defects in one or more venous sinuses may be imaged with MRI, MR venous angiography, conventional angiography, or radionuclide brain scanning. Associated edema or hemorrhagic infarcts may be obvious on MRI or CT scans.


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