Primary angiitis of the central nervous system: emerging variants

Abstract

Background: Primary angiitis of the central nervous system (PACNS), a serious disease, has not featured prominently in the spectrum of multi-organ disease seen in vasculitis clinics.

Aim: To evaluate the presentation, natural history and features of PACNS variants and compare to those of systemic vasculitides.

Design: Retrospective analysis.

Methods: Patients (n=105) presented during 1988-2003 to a tertiary regional vasculitis clinic receiving unselected disease types. Data were collected from a clinical database, patient and laboratory records.

Results: The frequency of PACNS presentation rose over the study period, compared with most of the other vasculitides. When PACNS was divided into small- and middle-sized vessel disease (SVD/MVD), their clinical courses differed substantially. SVD PACNS was responsive to immunosuppressive drugs, but relapsed during prolonged periods in all patients on maintenance immunosuppressives, or after withdrawal of treatment, causing recurrent, severe and irreversible CNS injury. MVD PACNS had isolated episodes at presentation, with a paucity of relapses during prolonged follow-up.

Discussion: Similarities between SVD PACNS and microscopic polyarteritis suggest the former may represent a limited form of the latter. MVD PACNS has a distinctly more benign relapse pattern than its multisystem counterpart polyarteritis nodosa. Acute-phase serology was useful in designating inflammatory processes at presentation of patients presenting with encephalopathy caused by SVD only, but were unhelpful in defining relapses in this form of PACNS, the definition of which in all cases rested on clinical assessment and MR scanning. Direct cerebral angiography was not diagnostic in any case of SVD PACNS; positive brain biopsy is diagnostically unequivocal, but the total clinical syndrome with imaging may establish a diagnosis with highest probability. In MVD PACNS, angiography with MR scan proved diagnostic. We suggest an algorithm for a rational, minimally invasive approach to investigation. In PACNS, SVD and MVD are important variants, and decisions about therapy should incorporate these distinctions.