Muscle Diseases Flashcards
Name 3 inflammatory myopathies?
- Polymositis
- Dermatomyositis
….both are idiopathic
- Polymyalgia rheumatica
Occurrence of polymyositis and dermatomyositis?
More common in females (2:1) with peak incidence at 40-50 years
Polymositis and dermatomyositis are assoc. with?
Increased incidence of MALIGNANCY, part. dermatomyositis
Histological features of polymyositis and dermatomyositis?
- Muscle fibre necrosis
- Degeneration and regeneration
- Inflammatory cell infiltrate i.e: the problem arises within the muscle ITSELF but the cause is unclear
Principal clinical feature of polymyositis and dermatomyositis?
MUSCLE WEAKNESS is the PRINCIPAL symptoms and has an insidious onset (over months)
Usually symmetrical and affecting the PROXIMAL muscles, so tops of arms and legs (drying/brushing hair, putting up washing, climbing stairs difficult due to weakness)
Other features in polymyositis and dermatomyositis?
Myalgia (muscle pain) CAN occur
Difference between polymyositis and dermatomyositis?
Dermatomyositis has signs of CUTANEOUS DISEASE
Cutaneous signs in dermatomyositis?
- Gottron’s sign (scaly erythematous papules or red patches overlying the MCP joints, elbows, and knees)
- Heliotrope rash (purple/red eyelids)
- Shawl sign (diffuse, flat, erythematous lesions over the back and shoulders, extending into a “V” on the upper chest; worsens with UV light)
Other organs affected by myositis?
Lungs (breathlessness may be caused by ILD or respiratory muscle weakness)
Oesophageal (dysphagia due to oesophageal and bulbar muscle inv.)
Cardiac (myocarditis)
Other systemic symptoms: fever, weight loss, Raynaud’s phenomenon, non-erosive polyarthritis (inflammatory)
Occurence of malignancy with polymyositis or dermatomyositis?
More common with dermatomyositis with the greatest risk in MEN > 45 YEARS
Tend to be ovarian, breast, stomach, lung, bladder and colon cancers
PMH assoc. with polymyositis or dermatomyositis?
Other autoimmune disease, such as diabetes mellitus and thyroid disease
DH assoc. with polymyositis or dermatomyositis?
Steroids
STATINS
SH assoc. with polymyositis or dermatomyositis?
Alcohol
Illicit drug use, esp. cocaine
Examination of polymyositis or dermatomyositis?
Confrontational testing - direct testing of power; will find that the person cannot resist the force pushing down on their arms and this is due to WEAKNESS
Isotonic testing (30 second sit and stand test); have the person cross their arms, to avoid help from upper limbs, and count how many times they can sit & stand in 30 secs
This is useful for monitoring the disease
Blood tests for polymyositis or dermatomyositis?
- Muscle enzymes, e.g: Creatine Kinase (CK) will be very high but it is non-specific
- Inflammatory markers will be raised
- Electrolytes, calcium, PTH, TSH to exclude other causes
- Auto-antibodies (ANA, Anti-Jo-1) - not present in all patients
Describe anti-Jo-1 antibodies
Myositis specific Ab that tends to be found in idiopathic inflammatory myopathies
Other diagnostic tools for polymyositis or dermatomyositis?
Electromyography (EMG) shows increased fibrillations, abnormal motor potentials and complex repetitive discharges
MUSCLE BIOPSY (DEFINITIVE TEST) shows perivascular inflammation and muscle necrosis
MRI shows muscle inflammation, oedema, fibrosis and calcification
Treatment of polymyositis or dermatomyositis?
- Glucocorticoids
- Immunosuppressants, e.g: azathioprine, methotrexate or ciclosporin
- IV immunoglobulin (tends to be for cutaneous features)
- Rituximab (B-cell depleting)
How to use steroids in poly and dermatomyositis?
Steroids (glucocorticoids), e.g: Prednisolone at 40 mg, are given as a bridging therapy until the immunosuppressants begin to work
Occurrence of inclusion body myositis?
Tends to be in patients > 50 years and is more common in MEN (3:1)
Differences between inclusion body myositis and polymyositis (for which it is often misdiagnosed)?
Responds more poorly to treatment
It has a more insideous onset (over YEARS)
DISTAL MUSCLE weakness (in polymyositis, it is proximal), e.g: weakness in the wrist & finger flexors in upper limbs and quadriceps &anterior tibial muscles in legs
ASYMMETRICAL weakness
Testing for inclusion body myositis?
CK levels are raised but are lower than in polymyositis
Muscle biopsy shows inclusion bodies
Table of main differences between polymyositis, dermatomyositis and inclusion body myositis?
Occurrence of polymyalgia rheumatica?
Occurs almost EXCLUSIVELY in those > 50 YEARS
Polymyalgia rheumatica is assoc. with?
Temporal arteritis/giant cell arteritis
Clinical signs of polymyalgia rheumatica?
- Ache in shoulder and hip girdle (PAIN IS THE PRINCIPAL FEATURE)
- Reduced movement of shoulders, neck and hips due to PAIN (not weakness); muscle strength is normal and this is shown if you can move their shoulder with no pain, as they are not using muscles
- Morning stiffness which improves with movement and they tend to have normal function at this point
- Usually symmetrical
- Fatigue, anorexia, weight loss and fever may occur
Time period of polymyalgia rheumatica?
Tends to develop RAPIDLY (over a few weeks); this sets it apart from poly and dermatomyositis
What is temporal arteritis/giant cell arteritis?
Granulomatous arteritis of large vessels
Symptoms and signs of temporal arteritis/giant cell arteritis?
- Unilateral headache
- Scalp tenderness
- Jaw claudication
- Tender, enlarged, non-pulsatile temporal arteries (no pulse is felt due to thickened arterial walls)
- Amaurosis fugax (painless transient monocular or binocular visual loss - not permanent)
Why must temporal arteritis/giant cell arteritis be treated urgently?
Can lead to BLINDNESS
Testing for temporal arteritis and polymyalgia rheumatica ?
No abnormal antibodies
INFLAMMATORY MARKERS are the ONLY abnormal finding and are raised (ESR, PV and CRP)
Temporal artery biopsy shows a narrowed lumen and thickened walls
Treatment of polymyalgia rheumatica?
Prednisolone 15 mg that is gradually reduced over 18 months to 2 years
If there is assoc. temporal arteritis, prednisolone 40 mg is gradually reduced over 18 months to 2 years
Outcome of polymyalgia rheumatica treatment?
Does NOT tend to recur
Describe fibromyalgia
COMMON cause of MSK pain and sleep disorder, part. in females (6:1)
It is NOT assoc. with inflammation and the aetiology of the pain is unknown
May begin after emotional/physical trauma and tends to occur in people who have significant, on-going stress
Fibromyalgia cycle?
Clinical symptoms of fibromyalgia?
• Diffuse and chronic pain in neck, shoulders, lower back, chest wall, etc (patients feel pain everywhere); it varies in intensity
Symptoms WORSE with EXERTION, FATIGUE and STRESS
- Sensation of swelling
- Debilitating fatigue and poor, unrefreshing sleep
- Pins and needles/tingling, headaches, depression, abdominal pain (IBS), poor concentration and memory
Examination of fibromyalgia?
Excessive tenderness on palpation of soft tissues (11/18 tender points indicates a diagnosis of fibromyalgia)
Testing for fibromyalgia?
There are NO DIAGNOSTIC TESTS and inflammatory markers are normal
There is an absence of another explanation for symptoms
Non-pharmacological treatment/management of fibromyalgia?
- Patient education
- Graded exercise programme
- Cognitive behavioural therapy
- Complementary medicine, e.g: acupuncture
Pharmacological treatment of fibromyalgia?
Tend to be unhelpful and the principals are to reduce drug therapy as much as possible:
- Anti-depressants, e.g: tricyclics may reduce pain and improve sleep
- Analgesia (not morphine sulphate)
- Gabapentin and pregabalin
