Polymyositis and Dermatomyositis

Mike Rafferty gives you a 3 minute overview of these important (yet difficult to understand!) connective tissue diseases.

 

Lecture by

Video Duration: 3 minutes

  • Polymyositis and Dermatomyositis
    Created by Harriet Bellenie
    General
    Epidemiology

    Polymyositis:

    Proximal muscle weakness and wasting.

    Dermatomyositis:

    Proximal muscle weakness and wasting with skin manifestations.

    Epidemiology Polymyositis/Dermatomyositis:

    Women:Men 2:1; ages 30-60 years, mean incidence age 50.

    Polymyalgia Rheumatica:

    Morning pain and stiffness in shoulders, neck and hips.


    Pathology

    Autoimmune

    Top three causes
    1. Autoimmune
    Clinical Features
    Symptoms

    Polymyositis and Dermatomyositis:

    • Proximal muscles weakness and wasting - difficulty in standing from sitting.
    • Dysphagia

    Polymyalgia Rheumatica:

    • Morning pain and stiffness in shoulders, neck and hips
    • Improves as day progresses
    • Systemically: low mood, lethargy.


    Signs

    Dermatomyositis - Skin manifestations

    • Gottrons papules over MCP joints
    • Heliotrophic rash over eyelids

    Polymyalgia Rheumatica:

    • Possible Low grade pyrexia
    • Associated with Temporal Arteritis


    Investigations
    Cultures

    Not necessary

    Bloods

    Polymyositis/Dermatomyositis:

    Creative Kinase: (elevated due to muscle breakdown)

    Anti-Jo antibodies: (positive in 20% of patients) - indicates poor prognosis and higher incidence of lung fibrosis.

    Polymyalgia Rheumatica:

    ESR: (may be raised implying associated Temporal Arteritis)

    Imaging

    Not necessary

    Scopic/Biopsy

    Polymyositis/ Dermatomyositis:

    Muscle Biopsy: Perifascicular inflammation is pathognomonic.

    Functional

    EMG: (to rule out other conditions such as Myasthenia Gravis)

    Treatment
    Conservative

    Polymyositis and Dermatomyositis: Physiotherapy

    Medical

    Polymyositis and Dermatomyositis: Steroids

    Polymyalgia Rheumatica: Prednisilone

    Surgical

    Not necessary