CNS involvement in systemic lupus erythematosus: a case with remarkable histopathological findings

Vasculitis in systemic lupus erythematosis

Vasculitis in connective tissue diseases is not an uncommon complication. Vasculitis complicates both rheumatoid arthritis and systemic lupus erythematosis (SLE) in about 4% of cases. Cutaneous lesions, representing small-vessel involvement, are most common; however, widespread, necrotizing visceral medium-and large-vessel involvement, mimicking primary vasculitic syndromes, may also occur. Connective tissue disease-associated vasculitis is separated from primary vasculitis syndromes in classification schemes. Granulomatous large-vessel disease does not occur in connective tissue diseases, suggesting a different pathogenesis. In most disorders, the etiology of vascular inflammation in not completely understood, but basic pathogenic mechanisms can often be distinguished. The role of immune complexes in the inflammatory manifestations of SLE is recognized, and other pathogenic factors such as antineutrophil cytoplasmic antibodies, common in other vasculitides, are infrequent. A diverse spectrum of clinical features, due to inflammatory involvement of arterial and venous vessels of all sizes, characterize several connective tissue diseases including Behçet's disease and SLE. The recognition of disease manifestations due to vasculitis in these disorders has important implications for treatment and may be critical to reduce morbidity and mortality.

The blood-brain barrier in systemic lupus erythematosus

Central nervous system (CNS) involvement may occur in 20-70% of systemic lupus erythematosus (SLE) patients where neurological symptoms are overt; this is termed neuropsychiatric lupus or NPSLE. This review summarizes evidence that damage to the brain endothelium forming the blood-brain barrier (BBB) is a contributory factor in NPSLE. The normal CNS is protected by blood-tissue barriers at three sites, the brain endothelium (BBB), the choroid plexus epithelium (blood-CSF barrier) and the arachnoid epithelium. The tight junctions of the barrier layers severely restrict entry of plasma constituents including proteins, so that the CSF and brain interstitial fluid contain low levels of protein. Methods for diagnosing BBB damage include imaging (CT, MRI) using contrast agents, and analysing protein content and profiles of CSF Changes in the albumin quotient Qalbumin show evidence for barrier damage, while changes in the immunoglobulin (Ig) index can indicate intrathecal antibody production. However, BBB damage may be transient, and hence undetected or underestimated. Few mechanistic studies exist, but the two main candidate mechanisms for BBB damage are microthrombi in cerebral vessels leading to ischaemia, and immune-mediated attack and activation of the endothelium leading to local cytokine production. Both can result in barrier breakdown. Neurological syndromes could then be secondary to damage to the BBB. The implications for treatment of NPSLE are discussed.

Imaging modalities in central nervous system systemic lupus erythematosus

Within the past few years, a clearly defined case definition system for central nervous system systemic lupus erythematosus (CNS-SLE) has been established. This has allowed cross-study comparisons of patients fulfilling the specific case definitions. New imaging techniques used on the subgroup of CNS-SLE patients that did not have any evidence for infarctions suggest that in these patients symptoms are associated with a diffuse process in the brain. Most likely this process leads to axonal damage and demyelination, ultimately leading to cerebral atrophy. With respect to the diagnostic work-up of SLE patients with neuropsychiatric symptoms, it has become clear that cranial magnetic resonance imaging is the technique of choice. Preliminary studies using quantitative magnetic resonance imaging techniques suggest that patients with neuropsychiatric symptoms caused by active CNS-SLE can be differentiated from patients with the same symptoms caused by residual disease.