An 11-year-old girl with myasthenia gravis presents for thymectomy. The patient has a history of ptosis, dysphagia, and generalized muscle weakness.
The medications she is using are pyridostigmine and prednisone.
Myasthenia gravis (MG) is an autoimmune disease in which antibodies are directed against the acetylcholine receptor at the neuromuscular junction. The disease is characterized by weakness and easy fatigability of voluntary muscles. Common symptoms include ptosis, diplopia, dysphagia, and dysarthria. Weakness of respiratory muscles may be severe during a myasthenic crisis. There are three types of myasthenia gravis that present in the pediatric population. Neonatal MG is a transient disorder caused by the passage of antibodies across the placenta from mothers who have MG, which may occur in 20%-30% of infants born to affected mothers. Congenital myasthenia is an autosomal recessive condition affecting the motor endplate. Juvenile MG usually presents in children over the age of 10, has a female predominance, and tends to have a presentation similar to that of the MG seen in adults: autoimmune in nature, often associated with an abnormal thymus gland, and classified as affecting either ocular muscles only or all voluntary muscles. Symptoms of MG worsen with exercise and tend to improve with rest. Medical therapy consists of treatment with cholinesterase inhibitors such as pyridostigmine and neostigmine to increase the available level of acetylcholine at the neuromuscular junction, as well as steroids to suppress the immune response. In a myasthenic crisis, IV immunoglobulin (IVIG) and/or plasmapheresis may be necessary. Surgical treatment with thymectomy can be curative, as antibodies to the acetylcholine receptor are produced by the thymus. Because of potential immunosuppression, thymectomy usually is deferred until the patient is at least 10 years old.
Preoperative evaluation should include a detailed history of the severity of weakness, specifically regarding bulbar and respiratory muscles. Pulmonary function tests are helpful if the child is cooperative.
Anticholinesterase medications increase airway secretions, potentiate narcotic effects, increase sensitivity to nondepolarizing muscle relaxants, and inhibit the metabolism of succinylcholine and ester local anesthetics. Ideally, anticholinesterase medications would be discontinued preoperatively, and the patient would be scheduled as the first case. However, discontinuation of anticholinesterase therapy in children with severe MG may cause aspiration or respiratory failure, so in these patients, medications are continued until surgery. Because of the autoimmune nature of MG, there is an association with thyroid dysfunction, which should be evaluated during the preoperative assessment.
Sedative premedication should be avoided because of possible potentiation effects of anticholinesterase therapy. Consider premedication with an anticholinergic drug such as glycopyrrolate to decrease excess salivation.
Continue any preoperative corticosteroids, and supplement with intraoperative stress dose hydrocortisone.
Induction and maintenance can be done with either volatile agents or IV agents such as propofol and remifentanil.
Do invasive blood pressure monitoring for the surgery itself, as ...
Log In to View More
If you don't have a subscription, please view our individual subscription options below to find out how you can gain access to this content.
Want remote access to your institution's subscription?
Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.
If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.
AccessAnesthesiology Full Site: One-Year Subscription
Connect to the full suite of AccessAnesthesiology content and resources including procedural videos, interactive self-assessment, real-life cases, 20+ textbooks, and more
Pay Per View: Timed Access to all of AccessAnesthesiology
24 Hour Subscription $34.95
48 Hour Subscription $54.95
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.