Abstract

INTRODUCTION

The inflammatory myopathies comprise a group of acquired myopathies in which muscle weakness and inflammatory infiltrates are the principal clinical and histological findings. Traditionally, a distinction is made between polymyositis, dermatomyositis and inclusion body myositis. This brief review will focus on polymyositis.

CLINICAL FEATURES

Diagnostic criteria

Polymyositis is characterized by symmetrical proximal muscle weakness. Respiratory, pharyngeal and neck muscles may also be involved during later stages of the disease (Dalakas & Sivakumar 1996; Mantegazza et al. 1997; Dalakas 1998a). Up to half the patients suffer from muscle pain or arthralgia. The history, clinical symptoms and signs, elevated serum levels of muscle enzymes, electrophysiological changes and histological findings together provide the basis for the diagnosis. The main diagnostic criteria and features are summarized in Table 1 for polymyositis and for the two other forms of idiopathic inflammatory myopathies, dermatomyositis, and inclusion body myositis. Clinically, poylmyositis and dermatomyositis are distinguished by