Myopathies Flashcards
What is the pathology the results from damage to an anterior (ventral) horn neuron?
Denervation atrophy
What is the most common form of spinal muscular atrophy?
Werdnig-hoffmann disease
Whatis the cause, signs and symptoms of Werdnig-Hoffman disease?
-degeneration of the cells in the anterior horn of the spinal cord and the motor buclei in the brainstem
–> lower motor neuron disease, leads to flaccid paralysis, especially of the trunk and limbs
–>floppy babies, lack of suckling and respiratory failure
What is the course of Werdnig-Hoffman disease?
- onset from birth to 4months
- death within 3 years
- type 1 spinal muscular atrophy
What is the inheritance pattern of Werdnig-Hoffman disease?
Autosomal recessive
What is the appearnece of Werdnig-Hoffman disease histologically?
grouped atrophy
What does an immuno peroxidase stain in BMD look like?
What is it called in DMD when the calves appear to enlarge before atrophy? What is really going on?
Pseudohypertrophy
-deposition of fat and connective tissue inbetween the muscle cells
What is the resulting action of type I and type II fibers in mytonic muscular dystrophy (DM)
- atrphy of Type I
- hypertrophy of Type II
What is the classic motion affected with DM?
-unable to relax from handshakes
What is a sign of DM in infants?
-Tenting of the upper lip
What is the histologic appearence of DM?
- central nuclei in cross section along with variation in fiber size
- fibrosis as well long strings of nuclei in longitudinal section
Central nuclei in DM
What is the cause of thyrotoxic myopathy?
-hypothyroidism
What are the signs and symptoms of thyrotoxic myopathy?
-proxmal muscle weakness
–>may precede exophthalmos
What is the cause of ethanol myopathy?
-Binge drinking
What is the pathophysiology of ethanol myopathy?
-acute myopathy
–>rhabdomyolysis leading to myoglobinuria
–>may lead to renal failure
What are the signs of steroid drug-induced myopathy?
- proximal muscle weakness
- muscle atrophy of type 2 fibers
What is another treatment that could result in drug induced myopathy?
-chloroquin (antimalarial)
What is the cause of Myasthenia Gravis?
-loss of ACh receptors due to biding of ACh antibodies
What are the first clinical signs of MG?
- weakness of extraocular muscles: ptosis and diplopia
- generalized weakness
What was the major cause of death in patients with MG?
-Respiratory compromise
What is the treatment of generalized weakness from MG?
-AChE inhibitors, prednisone. plasmapheresis
What is the pathophysiology of Lambert-Eaton syndrome?
- Content and binding of ACh vesicles is normal but antibodies to the Ca channels cause a reduction in response to stimulation.
- Repetitive stimulation leads to and increase in nerve conduction
