Muscle diseases

Question 1

What are the typical presentations of polymyalgia rheumatica (PMR)?

Answer 1

PAIN & STIFFNESS

Ache in shoulder and hip girdle
Morning stiffness
Usually symmetrical
Systemic presentation: Fatigue, anorexia, weight loss and fever may occur
Reduced movement of shoulders, neck and hips
Muscle strength is normal

Question 2

What is polymyalgia rheumatica?

Answer 2

Most commonly 50-60 y/o
Quite common
Incidence higher in northern regions
Associated with temporal arteritis/ giant cell arteritis (15%)

Question 3

How is blood test used for diagnosing PMR?

Answer 3

Inflammatory markers are the only abnormal indicators (Raised ESR, plasma viscosity, CRP), no antibody abnormalities

Question 4

How to manage PMR?

Answer 4

Rapid and dramatic response to low does steroids
Steroid dose: PMR - start at prednisolone 15mg daily

Question 5

What is inflammatory myositis?

Answer 5

WEAKNESS of muscle

Idiopathic inflammatory myopathies
Autoimmune
Peak incidence age 40-50 years

Question 6

Clinical features of inflammatory myositis

Answer 6

Muscle weakness
Insidious onset, worsening over months
Usually symmetrical, proximal muscles
Often specific problems eg difficulty brushing hair, climbing stairs
Myalgia in 25-50% (usually mild)

Question 7

What is Dermatomyositis?

Question 8

Clinical features of dermatomyositis?

Question 9

Investigations for dermatomyositis?

Answer 9

Anti-Mi 2

Question 10

What are other organs involved in inflammatory myopathies (dermatomyositis & inflammatory myositis)?

Question 11

What is antisynthetase syndrome?

Question 12

What is fibromyalgia?

Answer 12

PAIN & FATIGUE

Common cause of chronic musculoskeletal pain
NOT a disease of the muscle
Commonest cause of musculoskeletal pain in women 22-50 years
Prevalence of 2-5%
Commoner in women (F:M, 6:1)
May begin after emotional or physical trauma

Question 13

What are clinical presentations of fibromyalgia?

Question 14

How to manage fibromyalgia?

Answer 14

In general, avoid medication –> ineffective and addictive

Patient education
Multi-disciplinary response
Graded exercise programme
Cognitive behavioural therapy
Complementary medicine eg. acupuncture

Question 15

What is myopathy?

Answer 15

Myopathy is a disease of the muscle in which the muscle fibres do not function properly. This results in muscular weakness

Question 16

How to investigate inflammatory myositis?

Answer 16

1. Blood test
   Muscle enzymes eg. creatine kinase (CK)
   Inflammatory markers
   Electrolytes, calcium, PTH, TSH (to exclude other causes)
   Autoantibodies: ANA, Anti-Jo-1, Myositis specific antibodies
2. Electromyography (EMG):
   increased fibrillations, abnormal motor potentials, complex repetitive discharges

Question 17

How to diagnose inflammatory myositis?

Answer 17

1. Muscle biopsy: DEFINITIVE TEST. Perivascular inflammation and muscle necrosis
2. MRI: muscle inflammation, oedema, fibrosis and calcification

Question 18

How to treat inflammatory myositis?

Answer 18

Initial treatment: high dose corticosteroid + immunosuppression medications

eg. Mycophenolate Mofetil
Methotrexate
IV immunoglobulin
Rituximab

Question 19

What are differential diagnosis of muscle weakness?

Answer 19

Question 20

Rhabdomyolysis

Answer 20

Question 21

What is a side effect of simvastatin and how would combined use of diltiazem exacerbate this side effect?

Answer 21