74 Questions
Which type of lymphocytes are primarily produced by the thymus?
T lymphocytes
Which of the following is NOT commonly associated with paraneoplastic syndromes in thymoma patients?
Arthritis
What is the primary role of anticholinesterase medications in the treatment of myasthenia gravis?
Enhance muscle strength
Which of the following diseases is NOT specifically mentioned to be commonly associated with thymoma?
Multiple sclerosis
What is the significance of Lambert-Eaton myasthenic syndrome (LEMS) in terms of anesthetic management compared to myasthenia gravis?
Potential for prolonged muscle relaxation
Which type of T cells are responsible for fighting infection and cancer?
Helper T cells
During thymocyte maturation, which hormones in the thymus play a role in the development of T cells?
Thymopoietin and thymosin
What percentage of blood lymphocytes do T cells approximately account for?
65%
Which type of T cells was formerly known as suppressor I cells?
Regulatory T cells
What is the primary function of bone marrow stem cells in the context of T cell development?
Maturation into T cells in the thymus
Which type of T cell has a unique T-cell receptor that recognizes specific cell-bound antigens in lymphoid organs?
Memory T cells
Which part of the thymus is mainly composed of lymphoid cells?
Cortical portion
Where does the thymus receive blood supply from primarily?
Superior and inferior thyroid arteries
At what age does the thymus start to atrophy in response to increased sex hormone levels?
Puberty
Which veins drain venous blood from the thymus?
Innominate veins and thyroid sinus
What happens to the thymus gland over time as a response to increased sex hormones?
It decreases in size
Which immune system cells are primarily responsible for humoral immunity?
B lymphocytes (B cells)
What is the mainstay of treatment for thymomas?
Surgery
Approximately what percentage of all mediastinal tumors do thymomas account for?
20%
Which cell type gives rise to thymic carcinoid tumors?
Kulchitsky cells
In patients with myasthenia gravis (MG), what percentage are found to have a thymoma?
30% to 35%
What is the primary role of chemotherapy in the treatment of thymic tumors?
Shrinking large, malignant tumors preoperatively
Why is it preferable to delay thymectomy until puberty?
To allow for proper immune system development
What is a common symptom associated with thymomas due to phrenic nerve encroachment?
Chronic cough
Which of the following conditions is NOT commonly associated with thymomas?
Renal dysfunction
In what percentage of patients with thymomas is the mass discovered incidentally?
30% to 40%
What is a common paraneoplastic syndrome associated with thymomas affecting multiple systems?
Endocrine disorders
Which of the following is a rare feature of patients with thymomas?
Thymomas are common in children
What is a potential symptom in thymoma patients as a result of a paralyzed hemidiaphragm?
Shortness of breath (SOB)
What is the relationship between thymic dysfunction and immune function in adults?
Thymic dysfunction in adults does not affect immune function.
Which congenital disorder is associated with a lack of functional T cells and severe immunodeficiency?
DiGeorge syndrome
What is the primary target of antibodies in myasthenia gravis?
Postsynaptic nicotinic acetylcholine receptors
What is the role of alpha-fetoprotein in the context of myasthenia gravis?
It inhibits binding of maternal nAChR antibodies to fetal ACh receptors.
Which test is most sensitive for ocular and generalized muscle involvement in myasthenia gravis?
SFEMG
What happens to the architecture of the postsynaptic membrane in myasthenia gravis over time?
It takes on a simplified appearance with fewer nAChRs.
Which condition shows improvement in muscle strength within 5 minutes after administration of edrophonium as a confirmatory diagnostic test?
Myasthenia gravis
Which crisis is characterized by an acute exacerbation of symptoms associated with MG that requires immediate intubation and mechanical ventilation?
Myasthenic crisis
What can trigger acute hypoxemia, hypercarbia, and acidosis in a patient experiencing a myasthenic crisis?
Failure of the respiratory muscle to maintain adequate ventilation
Which of the following symptoms is associated with severe bulbar weakness and increased risk for aspiration during a myasthenic crisis?
Poor or absent gag reflex
What symptom differentiates a cholinergic crisis from a myasthenic crisis?
Preservation of deep tendon reflexes
Which condition is characterized by flaccid muscle paralysis due to overadministration of an anticholinesterase medication?
Cholinergic crisis
Which feature is NOT typically present during a cholinergic crisis?
Hypertension
Which approach is recommended for surgical access in patients with early-stage thymoma?
Upper sternal split with division of manubrium
What postsurgical complication is associated with thymectomy near the innominate vein?
Postoperative thrombosis
Why should the inspired oxygen concentration during anesthesia not exceed 28%?
To avoid pulmonary interstitial edema
Which test is NOT part of the preoperative testing for patients with a history of doxorubicin treatment?
CXR
What should be strictly observed during the insertion of intravenous lines in patients with a recent history of chemotherapy?
Use of aseptic technique
What is the primary reason for delaying thymectomy until puberty?
Reduced surgical risk
What is the purpose of an edrophonium challenge test in patients with myasthenic crisis or cholinergic crisis?
To distinguish between myasthenic crisis and cholinergic crisis
What is the immediate response expected during an edrophonium challenge test in a patient with myasthenic crisis?
Muscle strength improvement
Which side effect may warrant careful monitoring during an edrophonium challenge test in patients?
Significant bradycardia
What is recommended for patients with myasthenic crisis after an initial IV test dose of edrophonium?
Additional doses of an anticholinesterase
What is the primary management strategy for cholinergic crisis?
IV administration of atropine sulfate
In the context of thymomas, what is the primary goal of surgical resection?
Treating patients with a thymoma
For which stage of thymomas is surgery not indicated according to the text?
Stage IVb
What may be necessary for invasive stage IVa thymomas during surgery according to the text?
Resection of invaded local structures
What is the main aim of postoperative radiotherapy following complete resection in thymoma patients?
Decreasing recurrence rate
In thymoma patients, what surgical approach may be used to allow a simple thymectomy for myasthenic patients?
Video-assisted thoracoscopic surgery (VATS)
What is the primary concern in postoperative management for a patient with myasthenia gravis?
Development of postoperative respiratory failure
How do symptoms differ in unilateral versus bilateral phrenic nerve damage post-thymectomy?
Unilateral damage presents with respiratory difficulty and atelectasis, while bilateral damage results in reduced lung capacity
Why is mechanical ventilation often required in patients with bilateral phrenic nerve damage following thymectomy?
To support lung function due to paralysis of both hemidiaphragms
In the context of thymectomy, why is continued mechanical ventilation crucial for some patients postoperatively?
To manage hypoxemia and hypercapnia from phrenic nerve injury
What is the expected resolution time for transient neurapraxia following phrenic nerve injury during a thymectomy?
7-10 days
How do symptoms differ between unilateral and bilateral phrenic nerve damage following a thymectomy?
Unilateral damage manifests as hoarseness and atelectasis, while bilateral damage decreases vital capacity and total lung capacity
Which of the following medications is NOT associated with acute exacerbations of myasthenia gravis?
Tetracycline
Which of the following drug categories has NOT been linked to acute exacerbations of myasthenia gravis?
Antipsychotics
Among the following, which medication is paradoxically associated with acute exacerbations of myasthenia gravis?
Lithium
Which drug, commonly used in cardiac conditions, is associated with acute exacerbations in myasthenia gravis?
Quinidine
Which of the following medications has NOT been implicated in causing acute exacerbations of myasthenia gravis?
Trimethaphan
What is the primary role of acetylcholinesterase in the neuromuscular junction?
Breakdown of acetylcholine
In myasthenia gravis, what is the main consequence of a reduced number of postsynaptic acetylcholine receptors?
Impaired neuromuscular transmission
Where is acetylcholinesterase primarily located in the neuromuscular junction?
Synaptic folds
What is the consequence of failed neuromuscular transmission in myasthenia gravis?
Weakened muscle strength
What occurs to acetylcholine after its diffusion across the synaptic cleft in a neuromuscular junction?
Hydrolyzed by acetylcholinesterase
Learn about the thymus, T lymphocytes, thymomas, and paraneoplastic syndromes associated with thymomas. Understand the symptoms related to thymoma and how they can impact mediastinal structures or cause myasthenia gravis (MG).
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