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polymyositis
inflammation and necrosis of skeletal muscle fibers is immune mediated (CD8)
what antibodies in PM
Anti-SRP antibodies
what muscles are affected in PM
Symmetric, proximal muscle weakness (shoulders, thighs)
• Difficulty climbing stairs, rising from a chair, lifting objects
• Neck flexor weakness (difficulty holding up head)
• No significant pain (unlike polymyalgia rheumatica)
extramuscular involvement in PM
• Dysphagia (pharyngeal muscle weakness) → Aspiration risk
• Interstitial lung disease (ILD) → Progressive dyspnea, cough
• Arthralgia (joint pain, but no erosions)
• Cardiac involvement (rare, arrhythmias, myocarditis)
what is dermatomyositis
proximal muscle weakness and distinctive skin rashes. It involves humoral (B-cell) immune attack on muscle capillaries and perimysial connective tissue, unlike polymyositis, which is cell-mediated (CD8+ T cells).
what antibodies are in DM
Anti-Mi2 antibodies
Characteristic skin changes in DM
Heliotrope Rash- Violaceous rash on upper eyelids, often with periorbital edema
Gottron’s Papules- Raised, scaly erythematous plaques over MCP & PIP joints (pathognomonic)
Gottron’s Sign- Macular erythema over elbows, knees, or malleoli
Shawl & V Sign - Photosensitive erythematous rash over shoulders & upper chest
Mechanic’s Hands- Hyperkeratosis & fissuring of fingers (associated with anti-Jo-1)
diagnosis of PM and DM
• Muscle biopsy, the definitive test. (inflammatory cell infiltration and necrosis of muscle cells)
• Serum muscle enzymes (creatine kinase, aminotransferase, aldolase) are elevated.
• Positive ANA in more than 75%
• Anti-JO antibodies (anti-tRNA synthetase) are positive (1:
most common, 2: more in DM)
what changes in EMG are found in PM
o Short duration, low amplitude polyphasic units on
voluntary activation.
o Increased spontaneous activity with fibrillations,
complex repetitive discharges, positive sharp waves.
connective tissue diseases
Marfan’s Syndrome
Ehlers-Danlos Syndrome
marfan syndrome mutation in what
autosomal dominant disorder associated with mutation in fibrillin 1 gene on chromosome 15.
clinical features of marfan syndrome
• Clinical Features:
o Collagen abnormalities: fragility of the skin and bruising o Skeletal abnormalities: tall stature, arm span greater than height, arachnodactyly, sternal depression, hypermobile joints, high arched palate.
o Other features: upward dislocation of the lens & cardiovascular complications (Ascending aortic aneurysm formation & valve incompetence)
ehlers danlos syndrome
• Definition: inherited defect of collagen -> fragility and hyperelasticity of the skin
• Clinical features: easy bruising, “paper thin” scars, hypermobility of the joints, and rarely the weak walls of the aorta and gut may rupture.
muscle disorders
Myalgia: muscle symptoms without increased serum CK levels.
Myositis: muscle symptoms + elevated CK levels, after excluding causes of high CK.
Myopathy: primary functional or structural impairment of skeletal muscle, which can be acquired or hereditary
fibromyalgia
• Chronic widespread pain (≥3 months) & ≥
response to pressure
• 9 times more common in females
• Pain in at least 11 out of 18 tender points
• Fatigue, sleep disturbances, cognitive depression, foggy
• Partially respond to exercise & Amitriptyline
Myofascial pain syndrome
• Unbearable pain from one point of body to next
• Deep aching muscle pain, joint stiffness, areas of tension (knot-like feeling)
• Sites: arms/ legs, neck & back, buttocks, + many referred trigger points
• Treatment: analgesia, antidepressants, muscle relaxants, physiotherapy, acupuncture
Polymyalgia rheumatica
• Periarticular pain (shoulder & hips)
• Bilateral aching & stiffness
• Morning stiffness > 1 hour
• Fatigue, loss of appetite, weight loss
• VERY HIGH ESR **
Osteoporosis is a progressive systemic skeletal disease characterized by:
- reduced bone mass
- micro-architectural deterioraton of bone tssue
- increased skeletal fragility
- The normal bone remodeling process consists of diferent phases:
- Actvaton phase: osteoclasts recruited to the surface of the bone.
- Resorpton phase: osteoclasts generate an acidic microenvironment between the cell and the surface of the bone, dissolving the mineral content of the bone.
- Reversal phase: osteoclasts undergo apoptosis and osteoblasts are recruited to the bone surface.
- Formaton phase: osteoblasts then deposit collagen; this is mineralized to form new bone.
what is osteoclasts job
Osteoclasts dissolve old and damaged bone tssue so it can be replaced with new, healthier cells created by osteoblasts.,
Osteoclasts are the cells that degrade bone to initate normal bone remodeling and mediate bone loss in pathologic conditons by increasing their resorptve actvity
osteoblast job
Osteoblast:form new bones and add growth to existng bone tssue
what risk factors are from BMD dependent
1) Female sex/ hypogonadism Post menopausal osteoporosis: Estrogens stimulate osteoblast and inhibit osteoclast. The decreased estrogen level following menopause lead to increased bone resorpton
2) Immobilizaton
3) Chronic liver/ renal disease, COPD
4) GI disease , low dietary calcium intake, vitamin D defciency Endocrine ( cushing’s, hyperthyroidism , hyperparathyroidism )
5) Drugs ( heparin, antconvulsant, cyclosporin ) Most commonly due to systemic long term therapy with cortcosteroid
6) Others( diabetes, multple myeloma)
7) Caucasian/ Asian
risk factors that are BMD independent
1) Increasing age ( gradual loss of bone mass as patent age especially > 70 years)
2) Previous fragility fracture, family history, history of hip fracture Low BMI
3)Smoking and alcohol
4)Steroid therapy
5)Increased risk of falls
6)High bone turnover
7) Rheumatoid arthrits
Fragility fractures ( typically following minor trauma ) , which typically occur at 4 sitesin osteoporosis:
- Thoracic vertebrae (may lead to kyphosis and loss of height)
- Lumbar vertebrae
- Proximal femur
- Distal radius (Colles fracture)