Lower Motor Neuron

Class

Clinical Presentation

Etiology

Treatment

Autoimmune

Progressive muscle weakness w/ or w/o pain

CK elevated in active stage, and it is the most useful test for dx; CSR less helpful

Derm.: via circulating Ab’s

Poly.: involves T4 lymphocytes

Derm./Poly.: assoc. w/ autoimmune diseases

Modulate immune system

Inclusion body myositis: insidious, slow, painless

Biopsy shows inflammation and inclusions

Does not respond to immune modulation

Toxic

Colchicinemicrotubule damage

AZTmitochondrial toxicity

Steroids: if you give steroids to patients w/ myositis, be sure to distinguish primary sxs from side effects

Metabolic

Acid maltase: in infants, see muscle weakness, organomegaly (esp. tongue), cardiac involvement & death w/in a few mo.s

McCardle’s disease: muscle pain post exercise w/rhabdomyolysis increased CK

Critical illness myopathy: GI infection Txed w/ corticosteroidspatient now on ventilator and can’t wean off; dev. myosin deficiency

Takes mo.s to clear; Tx is supportive

Endocrine

Hypothyroidism: elevated CK & muscle inflammation

Hyperthyroidism: strabismus

Give all people w/ muscle disease a thyroid test

Hereditary

DMD: pseudohypertrophic calves, fibrosis and fat make muscles look bigger

75% have intellectual impairment

CK in the 1000s

Can usually talk and swallow until late in the course

FSH: scapula rises when you raise arms; no wrinkles on forehead