The collagen–vascular diseases represent the systemic expression of the immune system gone awry. In many cases, combinations of immune system dysregulation and nervous system involvement lead to some of the most challenging clinical conundrums in the neurosciences. In this chapter, we review the collagen–vascular diseases and their impact on the brain and peripheral nervous system.

Systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is the prototype of autoimmune diseases. The condition occurs throughout the world and is more prevalent in women (particularly during the reproductive years), with a female:male ratio of 9:1 (Gladman & Urowitz, 1998). To meet inclusion criteria for research studies as an SLE patient, a patient must demonstrate a minimum of 4 out of the 11 American College of Rheumatology (ACR) criteria (Table 96.1) (Tan et al., 1982). The criteria demonstrate the protean nature of SLE, which is capable of affecting any organ system. However, some patients clearly fit the spectrum of SLE yet do not fulfil minimum ACR criteria. Among the many neuropsychiatric manifestations of SLE, only seizures and psychosis were included in the 1982 criteria.

A 1999 nomenclature system for neuropsychiatric SLE (NPSLE) expanded the neuropsychiatric section of the ACR criteria, defining 19 neuropsychiatric syndromes associated with SLE. These are listed in Table 96.2 (ACR Ad hoc Committee, 1999). Usage of the terms ‘CNS lupus’, ‘lupus cerebritis’, ‘CNS vasculitis’, ‘lupus headache’, ‘lupoid sclerosis’, ‘brief reactive psychosis’, and ‘organic brain syndrome’ is discouraged. Neuropsychiatric manifestations may occur in up to two-thirds of patients with SLE (West, 1994) and range from anxiety, mood disorders, cognitive dysfunction and delirium to depression, frank psychosis, stupor and coma (Kovacs et al., 1993; Boumpas et al., 1995). Several conditions must be excluded before the attribution of neurological findings to NPSLE.

Pathogenesis

The pathogenesis of NPSLE remains elusive. It is probably more accurate to regard the ‘disease’ of SLE as a complex, heterogeneous group of disorders of unknown cause. Autopsy studies of patients with NPSLE have shown no pathognomonic lesions and frequently demonstrated poor correlation between clinical and pathological findings (West, 1994).