Inflammatory muscle disease Flashcards
What inflammatory muscle diseases exist?
¬ Polymyositis
¬ Dermatomyositis
¬ Inclusion body myositis
¬ Polymyalgia Rheumatica
Polymyositis and dermatomyositis:
- what are these?
- M:F
- Peak incidence of age
- what is the difference?
¬ Idiopathic inflammatory myopathies
¬ Prevalence 1/100,000
¬ Female:male 2:1
¬ Peak incidence ages 40-50 years
¬ Increased incidence of malignancy (particularly with dermato-)
15% incidence in dermatomyositis, 9% polymyositis
Ovarian, breast, stomach, lung, bladder and colon cancers
Risk greatest in men over 45 years
Muscle presentation is similar but in dermatomyositis there is skin involvement
What are the clinical features of poly/dermato myositis in the muscle?
¬ Muscle weakness ¬ Most common presenting feature ¬ Insidious onset, worsening over months ¬ Usually symmetrical, proximal muscles ¬ Often specific problems eg difficulty brushing hair, climbing stairs ¬ Myalgia in 25-50% (usually mild)
What skin signs are seen in dermatomyositis?
Gottrons sign :
pinkish skin over MCP & PIP
Heliotrope rash :
rash on upper eyelids and in some case lower eyelids too. Accompanied by itching and swelling
Shawl sign:
diffuse, flat, erythematous lesion over the back and shoulders or in a “V” over the posterior neck and back or neck and upper chest, which worsens with UV light
What other organ involvement is seen in poly/dermato myositis?
LUNG: Interstitial lung disease (10%)
Respiratory muscle weakness
OESOPHAGEAL: Dysphagia
CARDIAC: Myocarditis
OTHER: Fever, weight loss, Raynauds phenomenon, non-erosive polyarthritis
What is the gold standard investigation for poly/dermato myositis?
muscle biopsy
What other investigations are done for poly/dermatomyositis?
Blood tests:
¬ Muscle enzymes eg. Creatine kinase (CK)
¬ Inflammatory markers
¬ Electrolytes, calcium, PTH, TSH (to exclude other causes)
Autoantibodies: ANA, Anti-Jo-1 and anti-SRP
EMG - abnormal in almost all pts
MRI: This will help to indicate where to take the musce biopsy from
It can show inflammation / oedema / fibrosis / calcification
What is the treatment for poly/dermato myositis?
¬ Glucocorticoids ¬ Azathioprine ¬ Methotrexate ¬ Ciclosporin ¬ IV immunoglobulin
Reasonable high doses of oral steroids and alongside use immunosuppressant at first – this takes a while to work so monitor over time to see whether getting better:
-This consists of prednisolone (initially around 40mg) combined with immunosuppressive drugs such as methotrexate or azathioprine.
IV immunoglobulin – last resort
There is an associated risk of malignancy. This is found in around 25% in patients and is greatest in the 5 years following diagnosis. Common cancers include breast, ovarian, lung, colon, oesophagus and bladder.
Malignancy should be screened for at the time of diagnosis.
How is inclusion body myositis different from polymyositis?
¬ Can be misdiagnosed as polymyositis ¬ Patients >50 years ¬ Commoner in men (M:F, 3:1) ¬ More insidious onset ¬ Distal muscle weakness ¬ Weakness wrist and finger flexors in upper limbs and quadriceps and anterior tibial muscles in legs ¬ Weakness often asymmetrical
What is the diagnosis of inclusion body myositis?
¬ CK levels lower than in PM
¬ Muscle biopsy shows inclusion bodies
¬ Responds poorly to therapy (so maybe not worth using steroid?)
Polymyalgia rheumatica - epidemiology:
- peak age
- assoc. with
¬ Occurs almost exclusively in those over 50 years
¬ Prevalence of approx 1 %
¬ Incidence higher in northern regions
¬ Associated with temporal arteritis/giant cell arteritis (15%)
What are the clinical features of polymyalgia rheumatica?
¬ Ache in shoulder and hip girdle
¬ Morning stiffness – cardinal feature
¬ Usually symmetrical
¬ Fatigue, anorexia, weight loss and fever may occur
¬ Reduced movement of shoulders, neck and hips
¬ Muscle strength is normal
These patients are more acute and complain of pain and stiffness unlike myositis
What is the treatment for polymyalgia rheumatica?
Symptoms respond very dramatically to low dose steroids (prednisolone 15mg daily) and this is sometimes used as a diagnostic tool.
Prednisolone dose is gradually reduced over the course of around 18 months. By the end of this period the condition will have resolved in the majority of cases.
A dose of 40mg prednisolone daily should only be used if there is concern that the patient also has giant cell arteritis
Fibromyalgia:
-what are the signs and symptoms?
Persistent (≥ 3 months) widespread pain (pain/tenderness on both sides of the body, above and below the waist, and includes the axial spine [
Fatigue; disrupted and unrefreshing sleep
Cognitive difficulties
Multiple other unexplained symptoms, anxiety and/or depression, and functional impairment of activities of daily living (ADLs)
