Idiopathic inflammatory myopathy usually occurring in men over 50 years

Aetiology

• Idiopathic

Clinical features

• Slowly progressive weakness of mainly distal muscles
• Characteristic thumb sparing
• Weakness of the pharyngeal muscles causes difficulty in swallowing in over 50%

Investigations

• Bloods: CK only slightly elevated
• EMG: myopathic and neuropathic changes
• MRI: changes often more distal but similar to polymyositis
• Muscle biopsy

Management

• Prednisolone