2NEURO- Myasthenia Gravis Flashcards
What is destroyed in the neuromuscular junction in Myasthenia Gravis?
AUTOantibodies destroy AcH receptor is degraded w/in muscle
What is function of NT ACH?
Motor nerve receptor on muscle. Motor pathway
This theory involves rapid endocytosis L/2 turnover of receptors?
Cross linking Mech
This theory involves blocking of Ach receptor via what protein?
Autoantibodies
This theory involves damage of post-synaptic membrane?
Loss of folding d/2 complement mediate process
What is relationship btwn MG and normal msk function?
MSK- needs more stimulate. MG- 1. reduced transmiter d/t down reg or damaged membrane. 2. =30% less stimulation to target. 3. Atrophy, dec endurance 4. progressively decreasing response to repeate nerve stim.
Which tissue is affected in MG?
Skeletal msk. NO smooth, cardiac or sensory
What msk is must concerning if affected in MG?
Diaphragm
This structure is linked to play a role in MG?
Thymus retrosternal space. Adults should dissappear. Theory is thymus tissue migrate and destroy receptors. 75% have thymus or thymoma 10%
MG pts with Weakness in eye, limp, gait, and ptosis, diplopia are worsen by?
Stress, infx, menses, surgery, exertion
What is preserved on PE w/ MG?
DTRs. Proximal and Asymmetric limb weakness. Focus on
When the muscles that control breathing weaken to the point that ventilation is inadequate, creating a medical emergency and requiring a respirator for assisted ventilation?
Myasthenia Crisis- infx MCC
What is special to symptoms of MG?
- Upper limb common 2. Asymmetric 3. disappear w/ rest 4. Cooling nerve improves conduction
This lab test is will show +in 85% of the time?
Antibodies
If antibodies is negative, this test acetylcholinesterase inhibition increases pool of
available ACh. Improvement of symptoms immediate .
Edorphonium
What treatments are ideal for MG pts?
Neostigmine- ACHe inhibition allow ACh to accumulate. 2. PT very important 3. Steroids maybe . Thymectomy
What is no evidence based that supplement may work?
Vit K to suppress IL-6 related to thymus
Tx of MG can include cholinesterase inhibitors like neostigmine but these can be used for flare ups.
Steroid- help w/ suppression
This end result is the cause of fatigue associated with MG.
Depletion of NT stores - from more NT release required to facilitate contraction.
A female college student comes into your clinic complaining of weakness. She says when she goes to the gym her muscles fatigue really quickly like after a couple reps. She’s also wondering if she needs an eye exam because she starts to have trouble reading the words after ten minutes. The words become blurred. DeRosa suggested doing this task during your PE to help with you DD.
Pt hold sustained position. Ex. Hold gaze toward the celling.
If ptosis is a Sx an ice pack can be used to temporarily reverse the Sx
A Pt presents to your ER gasping for air and looking cyanotic. Her boyfriend says that she’s had a bad cold all week and is always coughing. When asked about medications he pulls a bottle from her purse with neostigmine printed on it. This is the probable cause for her respiratory distress.
Myasthenia Crisis –
Tx: inhabation, plasmapherisis, and intravenous immune globulin (IVIG)
In MG this mechanism, along with damage of post synaptic muscle membranes by antibodies and accelerated turnover of receptors by cross linking and endocytosis are the main cause of MG Sx.
Blockade of active sites on Ach receptor
