muscle pathology Flashcards
explain how muscle contraction occurs (action potential stimulation)
what is myaesthenia gravis + causes
Myasthenia gravis is a rare long-term condition that causes muscle weakness.
It most commonly affects the muscles that control the eyes and eyelids, facial expressions, chewing, swallowing and speaking.
- caused by antibodies to the nicotinic acetyl choline receptor at neuromuscular junction
what 3 blood tests might be done for a person with myasthenia gravis
- anti-acetyl choline receptor antibodies
- anti-Musk
- anti-LRP4
what do anti-acetyl choline receptor antibodies, anti-Musk, anti-LRP4 all have in common
all muscle directed anti-bodies
what are 3 potential treatments for myasthenia gravis
- acetyl choline esterase inhibitors (overloads remaining functional acetyl choline receptors)
- immunosuppressive treatment can treat underlying pathology
- surgical treatment of thymectomy (removal of thymus) can have therapeutic effect
what is thyoma
rare type of cancer arising in epithelial tissue of the thymus
what percentage of patients with thyoma will also have myasthenia gravis and hence what can be done to help reduce progression of myasthenia
30-40%
removal of thymoma can improve myasthenic disease progression
what is Lambert-eaton myasthenic syndrom
similar to myasthenic gravis
It is a miscommunication between the nerve cell and the muscles that lead to the gradual onset of muscle weakness.
what is a radiological significance with lamber-eaton
it is associated with paraneoplastic syndrome which means its a rare disorder that occur when the immune system has a reaction to a cancerous tumor known as a “neoplasm.”
why type of cancer is Lambert-eaton associate with typically
small cell lung cancer
what are the 3 components of the anaesthetic triad (general anaesthesia)
hypnosis
muscle relaxation
analgesia
what is duchene muscular dystrophy + cause
x-linked generic disorder that presents in childhood with weakness around pelvis
unlikely to live past 30 and are wheelchair bound
- caused by deficiency in dystrophin which links actin skeleton to extracellular matrix
(Lack of the dystrophin protein in muscle cells causes them to be fragile and easily damaged as gene on x-chromosome mutated)
what is facioscapulohumeral muscular dystrophy
genetic myopathy caused by excess expression of the DUX4 protein
affects muscle of face and shoulder girdle (clavicle and scapula providing bony link to arm and trunk)
winged scapula may be treated with surgery
what is steroid induced myopathy
corticosteroid ( reduce inflammation/overactive immune response) when taken long term can cause muscle atrophy (due to poor protein synthesis in muscles)
what are the type of muscle that steroid induced myopathy affects
high usage muscles e.g thigh
what is rhabdomyolysis
damaged muscle tissue releases its proteins and electrolytes into the blood/ damaged skeletal muscle breaks down rapidly
what can rhabdomyolysis be caused by
prolonged compression of muscle
extreme muscle exertion
certain medication (psychiatric-neuroleptic malignant syndrome)
what 3 things do the muscles in rhabdomyolysis release and why are they bad?
myoglobin- can lead to kidney damage and subsequent kidney failure
potassium- difficult for body to remove in during kidney failure and high levels can cause cardiac arrest
creatine kinase- not bad but used as check in blood test to see if damage has occured
what is statin induced myopathy
can cause muscle cramps (that subside with discontinuation of drug)
what is a good indicator in blood samples to show that there is statin induced myopathy
high levels of creatine kinase
