HY Myopathies

Question 1

dermatomyositis

Answer 1

• any age/gender
• subacute onset
• erythematous rash on FACE, UPPER BACK, HANDS
• weakness: proximal, symmetric, neck flexors, dysphagia (upper 1/3 of esophagus)
• associated with other CTD and MALIGNANCY
• diagnosis: biopsy
• Tx: immunomodulation (good outcome)

PERIVASCULAR

(mech: AutoAb against endothelial epitope causing complement-mediated small vessel injury (capillary vasculitis) = ischemic muscle death.)

Question 2

inclusion body myositis

Answer 2

• age: >60 years
• chronic onset
• weakness: QUADRICEPS, wrist/FINGER FLEXORS, dysphagia
• associated with CTD (thyroid) but not malignancy
• biopsy is diagnostic in clinical context
• Tx: immunomodulation (ineffective)

*exception to to myopathies having predominantly proximal m. weakness involvement

Question 3

dystrophinopathies

Answer 3

• Duchenne’s, Beckers
• X linked mutation of dystrophin gene (women can have less severe phenotype)
• symptomatic at 2-3, death in end of 3rd decade
• weakness: limb girdle, calf hypertrophy, tight heel cords
• associated cardiomyopathy, ventilatory muscle weakness, intellectual impairment
• dx: clinical, genetic

Question 4

fascioscapularhumeral muscular dystrophy

Answer 4

• autosomal dominant
• recognition from 1st decade to adulthood
• weakness most prominent in face, scapular fixators, biceps/triceps, foot dorsiflexors
• scapular winging occurs
• dx: clinical, genetic

asymmetric?

Question 5

myotonic muscular dystrophy

Answer 5

• autosomal dominant inheritance (DM1 and DM2)
• DM1 trinucleotide repeat disease
• variable age of onset
• variable severity
• weakness (cranial, DISTAL LIMB, ventilatory)
• associated myotonia (delayed relaxation)
• SYSTEMIC features: cardiac conduction defects, cataracts, smooth muscle involvement, frontal balding, temporal wasting
• dx: clinical, EMG, genetic

Question 6

polymyositis

Answer 6

an acquired, immune-mediated myopathy

attacks blood vessels

inflammatory myositis

confers risk of malignancy

responds to immunosuppressive tx

Question 7

see m. weakness of finger flexors and quads, think

Answer 7

inclusion body myositis

Question 8

polymyositis, dermatomyositis, inclusion body myositis all have elevated

Answer 8

CK

Question 9

polymyositis and dermatomyositis respond to ___________ tx, but inclusion body myositis does not.

Answer 9

immunosuppressive tx (steroids)

Question 10

polymyositis and dermatomyositis confer risk of

Answer 10

malignancy

Question 11

which drugs classically induce myopathies

Answer 11

steroids and statins

Question 12

metabolic myopathies are characterized by

Answer 12

exercise intolerance (not true weakness)

Question 13

Difference between Duchenne’s and Beckers

Answer 13

Duchenne’s –> young children, usually don’t live into adulthood

Beckers –> less severe mutation