Neuromuscular Disorders
Myasthenia Gravis
Autoimmune disease that attacks acetylcholine receptors and block acetylcholine binding.
Lack of acetylcholine -> impairs message at neuromuscular junction -> impaired muscle
contraction and weakness
Worsens after periods of activity, better with rest
**WEAKNESS IS SEVERE**
-effects face muscles and ability to breath
-ex. Get too tired to finish chewing food and could choke
Keywords/Breakdown
Myasthenia gravis=Lack of acetylcholine
Therefore-> treatment would be to prevent breakdown of acetylcholine so more is present/left
over
What kind of meds do this??? Acytelcholinesterase inhibitors!!!
{Acetylecholine}ster{ase} inhibitor
-ase is always talking about an enzyme that BREAKS DOWN something
So, acetylecholinestASE would BREAK DOWN acetylcholine
- HOWEVER, with myasthenia gravis, we need MORE acetylecholine so
we want to INHIBIT the breakdown of acetylcholine
- Inhibiting the breakdown of acetylecholine = More acetylcholine
available
TWO ACETYLCHOLINESTERASE INHIBITORS
1. Neostigmine -SHORT ACTING
2. Pyridostigmine- Intermediate acting
Both of these prevent breakdown of acetylcholine
Side Effects- pupil constriction, tearing, blurred vision, GI distress, fecal and urinary incontinence
LIFE THREATENING- bradycardia, dysrhythmias, COPD, hypertension and seizure
If you give too much of an acetylcholinesterase inhibitor -> too much acetylcholine in body ->
CHOLINERGIC CRISIS!!
-onest 30-60 minutes after acetylcholinesterase inhibitor
-severe muscle weakness, respiratory paralysis, pupil constriction, bradycardia
-GIVE ATROPINE
Acetylcholinesterase inhibitors help with lack of acetylcholine, but too much can be dangerous
too!
IF Preventing the breakdown of acetylcholine isn’t helping….next treatment is focused on
immune system because myasthenia gravis is an AUTOIMMUNE disease
IMMUNOSUPPRESSANTS:
Prednisone- a steroid
Plasma exchange- remove harmful substances
Immune globulin
Azathioprine- another type of immunosuppressant
Myasthenic Crisis- life-threatening exacerbation of myasthenia gravis
-threatens airway by weakening of diaphragm and intercostal muscles
-CAUSES: Stress (infection, emotional stress, extreme temperatures, surgery, etc.),
inadequate dosing of acetylcholinesterase inhibitors, HYPOkalemia
TREATMENT: Neostigmine
**Cholinergic Crisis (too much acetylcholine) and Myasthenic crisis (not enough acetylcholine)
can cause similar symptoms..(muscle weakness and respiratory distress. To determine if the
cause is cholinergic crisis or myasthenia crisis/myasthenia gravis -> perform edrophonium test
-if there is improvement with edrophonium -> cause is myasthenia gravis
-No improvement-> cholinergic crisis
Edrophonium is a very short acting acetylcholinesterase inhibitor
Main Nursing Process for Myastenia Gravis
-Assess for improvement in muscle strength
-Assess for cholinergic crisis after giving acetylcholinesterase inhibitor medication
-What to do during cholinergic crisis -> atropine
-What to do for myasthenic crisis-> neostigmine
-Unsure if its myasthenic or cholinergic crisis-> edrophonium
Multiple Sclerosis
Autoimmune
Not Genetic
Attacks myelin sheath- makes transmission of signals difficult to reach destination
-exacerbations and remissions
-difficult to diagnose
Causes:
Weakness and paralysis
Muscle spasticity
Joint pain, coordination issues
Veritigo, blurry or double vision, tinnitus
First line treatment is with Immunomodulators
Drug: beta interferon
-slows physical disability and decrease exacerbations
-Side effects: dizziness, depression, dyspnea, flulike symptoms, injection site rxn
Muscle Relaxants
Central acting Muscle relaxant
Drug: Cyclobenzaprine
-decrease muscle spasms and
Side effects: anticholinergic effects, drowsiness, dizziness headache
LIFE THREATENING- dysrhythmias
Nursing notes
*Check if patient has glaucoma before administration becasues of anticholinergic effects*
-monitor liver enzymes
-taper off slowly
-avoid alcohol
-short term medication
-fall precautions