Neuromuscular Diseases Part 2 Flashcards
What disease results in reduced acetylcholine receptors?
Myasthenia gravis
What disease’s clinical hallmark is skeletal muscle weakness that worsens with activity and improves with rest?
Myasthenia gravis
The severity of the disease directly _______ with the ability of antibodies to decrease the NUMBER OF AVAILABLE ACH RECEPTORS.
Correlates
Myasthenia gravis is more common in females or males?
Females
What is the age of onset for myasthenia gravis for females? Males?
20-30 yo
60-70 yo
What triggers myasthenia gravis?
The trigger is unknown.
True or false: 85% of myasthenia gravis patients have detectable antibodies.
True
The level of antibodies is directly correlated to severity in myasthenia gravis patients. True or false?
False. No correlation.
What other issues do myasthenia gravis patients have?
Thymomas
65% have hyperplastic thymus glands.
What are the clinical signs and symptoms of myasthenia gravis? (4)
Muscle weakness that worsens with activity
Improves with rest
Head and neck muscles affected early
Trunk and limb muscles affected later
What common physical symptoms do myasthenia gravis patients have? (2)
Ptosis
Diplopia
What exacerbates myasthenia gravis? (6)
Vaccinations Infection Stress Pregnancy Surgery Temperature changes --heat makes worse
Neonates of myasthenic moms will exhibit transient myasthenia gravis. True or false?
True.
It may last 1 to 3 weeks.
What is the treatment for myasthenia gravis? (5)
Anti-cholinesterase drugs like Neo Thymectomy Steroids Immunosuppressants Plasmapheresis to remove antibodies
If the patient has myasthenia gravis what is the risk or anesthetic concern if there is bulbar involvement? I.e. Can they stick out their tongue? Can they show their teeth?
Risk of aspiration!
What if myasthenia gravis has respiratory weakness? What is the anesthetic consideration?
They may need post op ventilation.
Pulmonary function tests may also be useful.
What are anesthetic considerations for myasthenia gravis patients? (4)
Risk of aspiration
Postop ventilation
Regional versus general anesthesia
Muscle relaxants
Myasthenia gravis have a _______ response to succinylcholine.
Decreased
Remember succinylcholine acts like acetylcholine so there is a lower response to succinylcholine.
The effective dose of succinylcholine will be ___ times normal in myasthenia gravis patients.
2
ED95 is 2.6
When giving nondepolarizing muscle relaxants to myasthenia gravis patients, what do you expect to happen?
Prolonged effects
Use much smaller dose or none at all if possible.
Use caution with neuromuscular blocker reversal with myasthenia gravis patients. True or false?
True
May want to consider Cis-atricurium to avoid using reversal.
In myasthenia gravis patients, what other drugs in conjunction with NMBs will potentiate block even more? (3)
Inhaled anesthetics
Magnesium
Aminoglycosides like gentamyacin
What are indicated risk factors for post op mechanical ventilation in myasthenia gravis patients? (4)
MG greater than six years
Additional chronic respiratory disease
Pyridostigmine dose > 750 mg/day
Preop vital capacity< 2.9 L
What are the causes of myasthenic crisis? (2)
Disease exacerbation
Inadequate drug therapy
Myasthenic crisis must be differentiated from cholinergic crisis which is caused by excessive anticholinesterase administration. True or false?
True
How do we differentiate a myasthenic crisis from a cholinergic crisis?
Tensilon test
What is Tensilon?
A short acting anti-cholinesterase
What does a negative result in a Tensilon test indicate for myasthenic patients?
Positive result?
Postop ventilation is required.
They get a little better.
Disease where antibodies attack Ca gated channel at presynaptic nerve terminals to decrease the release of ACH at NMJ
Myasthenic syndrome also known as Lambert Eaton syndrome.
What disease is associated with:
Small cell lung cancer
Proximal limb muscle weakness
Affects legs more than arms
Repeated effort improves muscle activity
Anti cholinesterase drugs have no benefit
Sensitive to both depolarizing and nondepolarizing muscle relaxants
Myasthenic syndrome
What is Lou Gehrig’s disease?
Amyotrophic lateral sclerosis
What is the most common progressive motor neuron disease?
Lou Gehrig’s disease