Muscle Diseases Flashcards
What is polymyalgia rheumatica?
A relatively common chronic inflammatory condition causing myalgia at the hip and shoulder girdles
How is polymyalgia rheumatic characterised?
- Proximal myalgia of the hip and shoulder girdles
- Mornign stiffness lasting > 1 hour
Polymyalgia rheumatica is strongly related to which other condition?
Giant cell arteritis
In what age is polymyalgia rheumatica most common?
> 50
Which blood tests can be done for polymyalgia rheumatica?
There are no specific tests
- CRP (will be raised)
- PV/ESR (will be raised)
Symptoms of polymyalgia rheumatic respond very well to which treatment?
Low dose steroids
(prenisolone 15mg)
The response is so dramatic that this can be used as a diagnostic tool
What is the treatment oplan for polymyalgia rheumatica involving low dosease steroids?
The steroid dose is gradually reduced over around 18 months
By this time the condition will have resolved in most patients
What is the most common form of systemic vasculitis?
Giant cell arteritis
Giant cell arteritis commony affects older/younger patients?
Older
How is giant cell arteritis characterised histologically?
- Transmural inflammation of the intima, media and adventitia
- Patchy infiltration by lymphocytes, macrophages and multinucleated giant cells (granulomas)
Vessel wall thickening in giant cell arteritis can result in what?
Subsequent distal ischaemia
What are the common signs and symptoms of giant cell arteritis?
- Visual disturbaces
- Headaches
- Jaw claudication
- Scalp tenderness
- Fatigue, malaise and fever may be present
Which condition should always be considered in the differential diagnosis of new-onset headaches in patients >50 with raised inflammatory markers?
Giant cell arteritis
Describe the headache patients may experience in giant cell arteritis
Continuous
Located in the temporal or occipital areas
Why does jaw cladication occur in giant cell arteritis?
There is temporal arteritis which causes subsequent ischaemia of the maxillary artery
Diplopia may be experienced in patients with giant cell arteritis, what is this?
Double vision
What is the most definitive test for giant cell arteritis?
Temporal artery biopsy
When should a temporal artery biopsy be done for a patient?
As soon as giant cell arteritis is suspected
Why is a positive temporal artery biopsy 100% specific, but only 15-40% sensitive for giant cell arteritis?
Giant cell arteritis is a diffuse condition and has patchy involvement
This means some segments of the artery will be normal
What are the typical biopsy findings in an artery with giant cell arteritis?
- Mononuclear infiltration
- Granulomatous inflammation (multinucleated giant cells)
What is the treatment for giant cell arteritis?
Corticosteroids
- Prednisolone 40mg (no visual impairment)
- Prednisolone 60mg (visual impairment)
When should treatment be started for giant cell arteritis?
As soon as the condition is clincially suspected
Describe the treatment program involving corticosteroids for giant cell arteritis
The prednisolone dose is gradually tapered over 2 years
After this time, the condition will have resolved for most patients
What is polymyositis?
An idiopathic inflammatory myopathy that caused symmetrical proximal muscle weakness
How is dermatomyositis different from polymyositis?
It has typical cutaneous manifestations as well as the other symptoms
Both polymyositis and dermatomyositis are more common in which sex, and which age group?
Females
Adults > 20, especially 45-60
What is the basic pathogenesis of polymyositis?
It is thought that CD8 T cells and macrophages surround healthy muscle tissue and initiate a cytotoxic response
(an autoimmune response to both nuclear and cytoplasmic antibodies in seen in most patients)
Which antibodies are associated with polymyositis and which of these are specific for polymositis/dermatomyositis?
- ANA
- Anti-RNP
- ANti-Jo-1 (specific)
- Anti-SRP (specific)
How do patients with polymyositis present and what is the onset of the condition?
Symmetrical, proximal muscle weakness in the upper and lower extremities
Some patients also have myalgia
(insidious in onset)
Why may dysphagia occur in polymyositis?
Secondary to oropharyngeal and oesphageal involvement
(a poor prognostic sign)
Which lung condition is commonly found in those with polymyositis that are postive for anti-Jo-1 antibody?
Interstitial lung disease
Which investigations are suitable for polymyositis/dermatomyositis?
- Inflammatory markers
- Serum creatinine kinase
- Autoantibodies
- MRI
- Electromyography
- Muscle biopsy
Why is muscle biopsy crucial in polymyositis/dermatomyositis?
It can exclude other rare muscle diseases
What does a muscle biopsy classically show in polymyositis/dermatomyositis?
Muscle fibres in varying stages of inflammation, necrosis and regeneration
What is the management of polymyositis/dermatomyositis?
Prednisolone (40mg)
Immunosuppressive drugs e.g. azathioprine or methotrexate
What are the classical cutaneous features of dermatomyositis?
- V-shaped rash over chest
- Gottron’s papules
- Heliotrope rash
There is an associated risk of malignancy with dermatomyositis patients, which types of cancer are most common?
- Breast
- Ovarian
- Lung
- Colon
- Oesophagus
- Bladder
What is fibromyalgia?
An unexplained condition causing widespread muscle pain and fatigue
Fibromylagia is most common in which sex and age?
Females
Young and middle aged
What is fibromyalgia thought to be?
Disorder of central pain processing
or
Syndrome of central sensitivity
Patients with fibromyalgia tend to have a lower threshold of which things?
- Pain
- Heat
- Noise
- Strong odours
Fibromyalgia can occur as a primary or secondary condition. When it occurs as a secondary condition, which conditions is it associated with?
- RA
- SLE
How does fibromyalgia clinically present?
- Persistant widespread pain (> 3 months) on bopth sides of the body, above and below the waist and including the axial spine
- Fatigue and unrefreshing sleep
- Cognitive difficulties
- Anxiety, depression, IBS and migraine
Which conditions may present similiarly to fibromyalgia?
- Hypothyroidism
- RA
- SLE
- Polymyalgia rheumatica
- Other inflammatory autoimmune conditions
What is the management of fibromyalgia like?
- Education of self-management techniques
- Graded exercise
- Atypical analgesia (amitriptyline)
- Gapapentin
- Pregabalin
- Cognitive behavioural therapy
