Polymyositis & Others

Polymyositis 

 

Definition 

 

Disease of unknown aetiology produces inflammation and muscle degeneration

 

Epidemiology

 

Begins in childhood

More common in females

 

Symptoms 

 

Proximal muscle weakness

- muscles tender & swollen

- brawny & indurated

 

Arthralgias 

- frequently hands, wrists, and knees 

 

Starts with systemic symptoms

- skin rash, fever, malaise

 

Investigations

 

Creatine Phosphokinase elevated

 

Muscle biopsy

- inflammatory infiltration & necrosis

 

Xray

 

May see subcutaneous calcification

- classically seen in the proximal large muscles

- occasionally, the calcification assumes a sheet-like pattern along fascial or muscle planes

- is considered nearly pathognomonic for dermatomyositis

 

Management

 

Acute

- symptomatic

- corticosteroids

- immunosuppressive medication for resistant cases

 

Chronic

- physiotherapy

- orthotics

- surgical release of contractures

 

Dermatomyositis

 

Epidemiology

 

Can occur at any age 

- peak in childhood

- peak in late adulthood

- more common in females

 

Clinical Features

 

Similar to polymyositis

 

Rash more prominent

- photosensitive

- malar butterfly distribution

 

Management

 

As for polymyositis

 

Complications

 

Associated with neoplasm in 10-20%

 

Polymyalgia Rheumatica

 

Epidemiology

 

Middle aged women

 

Symptoms

 

Tender pectoral & pelvic muscles

 

Risk Temporal Arteritis

 

Investigations

 

ESR high

 

Management

 

Rapid response low dose steroids

 

Postinfectious Arthritis

 

Aetiology

 

Meningococcal arthritis 

- most commonly

 

Streptococcal arthritis 

- occasionally

 

Represents Arthus reaction 

- interaction of newly produced circulating antibodies & bacterial antigens in synovium

- interaction produces immune complexes & inflammatory response

 

Sarcoidosis

 

Aetiology

 

Unknown cause 

- characterised by non-caseating granulomata 

- can affect any organ at any age 

 

Clinically

 

Most commonly affects the chest in young adults

- bilateral hilar lympadenopathy

- cough, fever, arthralgia, malaise, erythema nodosum 

 

Also affects

- skin - rash

- eyes - uveitis

- heart

- CNS - hearing, balance

- renal

- MSK system

 

Two Musculoskeletal Forms

 

Symmetrical small joint polyarthropathy without bony involvement

- erythema nodosum

- hilar lymphadenopathy

 

Chronic granulomatosis bony involvement

- polyarthritis

- tenosynovitis

- punched out lucent bony "cyst"

- especially hand & feet

 

Scleroderma

 

Definition

 

Autoimmune Disease

 

CREST Syndrome

1. Calcinosis

2. Raynaud's

3. Esophageal Strictures

4. Sclerodactyly

5. Telangiectasia

 

Clinical Features

 

Typical patient middle aged female 

- cushingoid facies

 

Hands

 

Stiff shiny digits with loss of creases and flexion contractures 

- autoamputation / acro-osteolysis - osteolysis of the tufts of DP (80%)

- punctate calcification of the terminal phalanx

- telangiectasia

- calcium nodules

 

Important to consider vascular supply to hand prior to OT

 

Extraskeletal 

 

Lung fibrosis

CRF

Calcification (subcutaneous, extra-articular, occasionally intra-articular

 

Xray

 

Calcification in ST of digits

Osteopenia

Joint erosion

 

Investigations

 

DDx RA

- up to 40% scleroderma have positive RF