Musculoskeletal diseases Flashcards
Select the statement that BEST describes myasthenia gravis.
a. pregnancy reduces the severity of the symptoms
b. neonates of affected mothers are at risk for muscle weakness
c. Edrophonium impairs muscle strength during symptom exacerbation
d. Acetylcholine production is decreased
B. neonates of affected mothers are at risk for muscle weakness
Myasthenia gravis is an
autoimmune disease in which IgG antibodies destroy post-junctional nicotinic receptors at the neuromuscular junction leading to skeletal muscle weakness
Signs and symptoms of myasthenia gravis includes
ptosis, dysphagia, dysarthria, and proximal muscle weakness
The first line medical treatment for myasthenia gravis is
oral pyridostigmine
Overdose of anticholinesterases leads to
cholinergic crisis and muscle weaknesis
______________ will help you determine if weakness is due to cholinergic crisis or myasthenic crisis.
Tensilon test
The ______ plays a key role for patients with myasthenia gravis, and ___________ brings symptom relief to many paitents.
thymus gland; thymectomy
A key feature of myasthenia gravis is
skeletal muscle weakness that becomes worse later in the day or that develops with exercise; periods of rest allow for the recovery of skeletal muscle function
Situations that exacerbate myasthenia gravis include
pregnancy
infection
electrolytes abnormalities
surgical and psychological stress
aminoglycoside antibiotics
How does myasthenia gravis affect neonates of mother’s with the condition?
anti-AchR IgG antibodies cross the placenta and cause weakness in 15-20% of neonates
this can persist up to 2-4 weeks
Treatment for myasthenia gravis includes
anticholinesterases
immunosuppression
plasmapheresis
surgery (thymectomy)
The patient with myasthenia gravis will be (select 2):
a. sensitive to vecuronium
b. resistant to rocuronium
c. sensitive to succinylcholine
d. resistant to succinylcholine
a. sensitive to vecuronium
d. resistant to succinylcholine
Patients with myasthenia gravis have ________ receptors at the neuromuscular junction.
fewer nicotinic receptors
Patients with myasthenia gravis have _________ to nondepolarizing NMBs.
increased sensitivity
Patients with myasthenia gravis have _______ to depolarizing NMBs.
increased resistance or decreased sensitivity
If a neuromuscular blocker is used for patients with myasthenia gravis, there is an increased risk of
residual neuromuscular blockade
Bulbar muscle weakness (mouth and throat) manifests as
difficulty handling oral secretions; this increases the risk of pulmonary aspiration
How does pyridostigmine (the mainstay of medical management for myasthenia gravis) affect succinylcholine?
prolongs the duration of succinylcholine because it impairs the efficacy of pseudocholinesterase
Patients with myasthenia gravis should be counseled on
the need for postoperative ventilation
There is an increased risk for postoperative ventilation for patients with myasthenia gravis with
disease duration >6 years
daily pyridostigmine >750 mg/day
vital capacity <2.9 L
COPD
surgical approach: median sternotomy> transcervical thymectomy
Identify the characteristics common to Eaton-Lambert syndrome. (select 3)
a. destruction of voltage-gated calcium channels
b. bulbar muscle weakness
c. diagnosed with Tensilon test
d. destruction of the nicotinic receptor
e. increased sensitivity to succinylcholine
f. small cell lung carcinoma
a. destruction of voltage-gated calcium channels
e. increased sensitivity to succinylcholine
f. small cell lung carcinoma
Eaton Lambert syndrome is a
disorder of the neuromuscular junction that results in skeletal muscle weakness
caused by IG-mediated destruction of the presynaptic voltage-gated calcium channel at the presynaptic nerve terminal
____________ increases ACh release from the presynaptic nerve terminal and improves the strength of contraction.
3,4 diaminopyridine (DAP)
Are anticholinesterases helpful for Eaton-Lambert syndrome?
No
Can the Tensilon test be used to diagnose Eaton-Lambert syndrome?
No
How do patients respond to paralytics when they have Eaton-Lambert syndrome?
patients are sensitive to succinylcholine & non-depolarizers (reduce doses)
Reversal with anticholinesterases for those with Eaton-Lambert syndrome may be
inadequate despite proper dosing
Describe the postsynaptic nicotinic receptors with Eaton-Lambert syndrome.
Present in normal quantity and function normally; we just don’t see the adequate release of acetylcholine to simulate them
Patients with Lambert-Eaton syndrome are at high risk for postoperative
ventilatory failure
Upwards of 60% of patients with Eaton-Lambert syndrome have
small-cell carcinoma of the lung (oat-cell carcinoma)
consider the possibility of this disorder in all patients with suspected lung cancer undergoing mediastinoscopy, bronchoscopy, or thoracoscopy
What is the clinical presentation of Lambert-Eaton syndrome?
proximal muscles are affected with weakness generally worse in the morning and better throughout the day
respiratory musculature and diaphragm become weak
autonomic nervous system dysfunction causes orthostatic hypotension, slowed gastric motility, and urinary retention
Which disease begins with an influenza-like illness that is followed by ascending paralysis?
a. familial periodic paralysis
b. myotonic dystrophy
c. Charcot-Marie-Tooth
d. Guillain-Barre syndrome
d. Guillain-Barre syndrome
________ is the most common cause of acute, generalized paralysis.
Guillain-Barre syndrome
Guillain-Barre syndrome is characterized by
an immunologic assault on myelin in the peripheral nerves
Medical treatment for Guillain-Barre syndrome includes
plasmapheresis and IV IgG
steroids are not useful
Can regional anesthesia be used with Guillain-Barre syndrome?
controversial d/t inconclusive data
Describe the use of neuromuscular blocking drugs with Guillain-Barre syndrome.
avoid succinylcholine
decrease the dose of nondepolarizing NMBs
Describe the onset of GBS.
flu-like illness usually precedes paralysis by 1-3 weeks
usually persists for 2 weeks and ends with full recovery in 4 weeks
Describe the symptoms of GBS.
flaccid paralysis usually begins in the distal extremities and ascends bilaterally towards the proximal extremities, trunk, and face
muscle weakness impairs ventilation and causes difficulty swallowing (risk of aspiration)
GBS is characterized by
an immunologic assault on myelin in the peripheral nerves
the action potential can’t be conducted so it never reaches the motor endplate
Etiologies of GBS include
Campylobacter jejuni bacteria, Epstein-barr virus, cytomegalovirus, vaccinations, surgery, and lymphomatous disease
Patients with GBS may have _________ necessitating the use of _______ intraoperatively
autonomic dysfunction requiring intra-arterial pressure monitoring
Patients with GBS have an exaggerated response to __________ due to the upregulation of postjunctional adrenergic receptors
indirect-acting sympathomimetics
What is another name for GBS?
acute idiopathic polyneuritis
