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Neuromuscular Junction Syndromes and Ocular Myopathies
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Edrophonium can cause multiple side effects related to the increased muscarinic activity, including abdominal cramping, lacrimation, salivation, sweating. Continuous cardiovascular monitoring during its performance is necessary, in order to avoid more serious side effects, such as bradycardia, hypotension, and syncope, sometimes requiring the use of atropine. The Neostigmine test can be used as a safer and easier alternative to edrophonium testing: it is a longer acting drug (30 minutes), allowing a more detailed post-treatment evaluation which is valuable for measuring diplopia, for instance.
Neurologic disorders in pregnancy
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Robert Burger, Terry Rolan, David Lardizabal, Upinder Dhand, Aarti Sarwal, Pradeep Sahota
Myasthenia gravis (MG) occurs predominantly in women of reproductive years with peak incidence in third decade (41). Management of MG in a pregnant woman is a unique challenge needing many therapeutic decisions at different stages. The course of MG during pregnancy is unpredictable with exacerbation in about 40%, remission in 30%, and no change in the remaining (24,42,43). The risk of worsening is the greatest during first trimester and early puerperium, and in women with recent diagnosis of MG (31). Women with MG who are considering pregnancy should be instructed on optimal disease control, minimizing oral immunosuppressants, and risks to mother and fetus. Elective thymectomy if being considered should be done before pregnancy as the benefit of thymectomy is delayed (24,41). Treatment with acetylcholinesterase inhibitors (pyridostigmine, edrophonium) and prednisone is safe during pregnancy. Immunosuppressive agents such as azathioprine and mycophenolate mofetil are contraindicated (41,43). Aggressive treatment is needed in patients with bulbar or respiratory involvement. Plasmapheresis or intravenous immunoglobulin therapy can be used for control of severe symptoms and in myasthenic crisis (41). Maintenance IVIG therapy can help to avoid the use of immunosuppressive agents. There is higher risk of maternal mortality in myasthenic women especially within 1year of diagnosis (42). It is advisable for MG women to delay childbirth for 2years after the onset of illness.
Drugs Affecting the Autonomic Nervous System
Published in Radhwan Nidal Al-Zidan, Drugs in Pregnancy, 2020
Risk Summary: It should be used with caution during the 1st and 2nd Trimesters. However, it is better to avoid the use of Edrophonium during the 3rd Trimester because fetal toxicity has been associated with its use during the last Trimester.
Myasthenic crisis as an initial presentation of myasthenia gravis in an 81-year-old following endoscopic myotomy for Zenker’s diverticulum
Published in Baylor University Medical Center Proceedings, 2023
Daniel Tran, Lucas Fair, Bryana Baginski, Bola Aladegbami, Steven Leeds, Marc Ward
Physical examination may reveal muscle weakness, ptosis, or impaired extraocular movements. However, physical examination may reveal normal muscle strength due to a fluctuating disease pattern. In these cases, repeated muscle use can demonstrate weakness. In a patient with suspected MG, serum testing for AChR antibodies is the first recommended step in diagnosis.7 Multiple other diagnostic tests can be performed. Electrodiagnostic techniques, such as nerve conduction studies and routine needle electromyography, can be performed to exclude alternative diagnoses or to confirm a concomitant disorder.7 Pharmacologic testing with edrophonium can be used, but is associated with serious adverse reactions.8 The ice pack test is a quick and simple bedside method that can be used. If there is improvement in ptosis after ice is placed on a closed lid for 2 minutes, it is a positive test result.9
A cluster of tetrodotoxin poisoning in Oman
Published in Clinical Toxicology, 2022
Badria Alhatali, Sultan Al Lawatia, Faryal Khamis, Sandeep Kantur, Seif Al-Abri, Vikas Kapil, Jerry Thomas, Rudolph Johnson, Elizabeth I. Hamelin, Rebecca M. Coleman, Ziad Kazzi
There is no specific antidote for TTX intoxication. The management is mainly based on supportive care. This includes intubation and mechanical ventilation for respiratory failure, intravenous fluids and vasopressors for hypotension, atropine for bradycardia, and hypersalivation [18]. Acetylcholinesterase inhibitors such as neostigmine or edrophonium have been used in tetrodotoxin-induced respiratory failure. They inhibit the breakdown of acetylcholine at the neuromuscular junction and may overcome the blockade of the nicotinic receptor at the neuromuscular junction [16,19]. The recommended dose of neostigmine is 1.5–2.5 mg IV every 6 h for a total duration of 24 h [11,16,19]. Pretreatment with edrophonium 10 mg before neostigmine appears to accelerate recovery of muscle power [20]. Neostigmine does not cross the blood-brain barrier and would not affect the medullary respiratory center in the Central Nervous System in which the toxin exerts inhibition of respiration in addition to its effect at the neuromuscular junction [19]. Unfortunately, there is currently insufficient evidence to support or refute the use of neostigmine in patients with tetrodotoxin-associated respiratory failure. Most data consist of case series [16].
Quantification of Cover Test Prior and Post Pyridostigmine in Diagnosis of Myasthenia Gravis
Published in Journal of Binocular Vision and Ocular Motility, 2021
Marta Saint-Gerons, Miguel Angel Rubio, Ana Martinez, Ana Matheu
The most accepted pharmacological test for the diagnosis of MG is the Tensilon® test with edrophonium chloride, another reversible acetylcholinesterase (AChE) inhibitor.14 The sensitivity of the edrophonium test for the detection of OMG is 88–97% and the sensitivity around 50–83%.2 Edrophonium test can cause adverse cardiovascular effects and should be used with precaution in patients with heart disease or in patients taking atrioventricular node-blocking drugs. The test may also be complicated by cholinergic side effects. Consequently, the edrophonium test has been increasingly replaced by the noninvasive rest/sleep and ice bedside tests.1 Kubis et al.15 reported a sensitivity of 50% for the rest test although its specificity was high 100%. M Benatar13 estimates a sensitivity of 95% (90–99%) and a sensitivity of 97% (94–100%) of seven studies that describe the accuracy of the ice test in ocular and generalized myasthenia, even if the value is questionable given the heterogeneity between studies.