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Myasthenic crisis

Perform a thorough respiratory assessment on all patients with myasthenia gravis presenting to the emergency department. Subjective air hunger, rapid respiratory rate, and accessory muscle use are all signs of impending respiratory failure. A rapid bedside test is to ask the patient to count as long as they can on a single breath. Normally, one should be able to count easily to 30. Patients who are unable to get to 20 are likely to have significant impairment of their respiratory muscles.

Finally, pulmonary function testing can be helpful, with a forced vital capacity less than 15-20 mL/kg representing severe disease and probable need for intubation. (The value of PFTs in myasthenia…

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 EM@3AM: Myasthenia Gravis and Crisis

Generalized weakness is the most common symptom, typically of the proximal muscles, neck extensors, and facial/bulbar muscles (diplopia, ptosis, dysphagia, dysarthria). Ptosis is often the first symptom.

Articles of Interest

Oh Me Nerves! A Neurology Medley

Recognize the diagnosis, can often be forgotten especially if it is the initial presentation of the disease. Look for precipitate (40% associated with respiratory infections). Differentiate from cholinergic crisis (often impossible to do). No case reports in literature. Discontinue pyridostigmine – can worsen bronchial secretions and increase risk of arrhythmia.

Emergency Room Experiences with Myasthenia Gravis are Traumatic

Often, I find myself frantically worrying about the competency of medical professionals treating my “special case.” I have never entered an emergency room without the fear that clinicians will accidentally kill me with medications they did not know are contraindicated for MG or the therapies I use to treat it.

A grave disease: Myasthenia Gravis

As an emergency physician, you are unlikely to outright diagnose myasthenia gravis, but you are much more likely to manage a myasthenic crisis. A myasthenic crisis is defined as worsening weakness leading to respiratory depression and eventual intubation or NIPPV. ~20% of patients will experience a crisis at least once in their disease course. In fact, in ~20%, a crisis is the initial presentation of myasthenia. Rapid therapies for those in myasthenic crisis include plasma exchange and IVIG. These start to have effect in several days, and therefore do not play a role in management in the ED and are typically started in the ICU. Your only job in the ED is to admit the patient to the ICU and discuss elective intubation. Elective intubation is much preferred over “urgent” or “emergent,” as the procedure is more controlled, and outcomes are better.

Advanced Practice: Respiratory Failure in Myasthenia Gravis Crisis

Vital Capacity (VC) and Max Inspiratory Pressure (aka Negative Inspiratory Force) are most important to monitor during crisis.Consider intubation if VC below 15-20 ml/kg OR MIP/NIF less negative than -25 to -30 cmH2O.

Drugs to Avioid In Myasthenia Gravis

A list including steroids...

EmergiQuiz: Myasthenia Gravis

Though respiratory muscle function gets all the press, and rightfully so – ocular function can be an early sign that is easily missable. Think about how many times have you written “pupils are equal round and reactive to light” and “extraocular muscles are intact” in your note? What if a patient has ptosis, do you fully assess lid elevation? Ask to see a recent picture of the child for comparison? Teasing out early ocular involvement especially can be challenging.

Five pearls for the dyspneic patient with Guillain-Barre Syndrome or Myasthenia Gravis

Guillain-Barre Syndrome (GBS) and Myasthenia Gravis (MG) are common causes of acute weakness. About 25% of these patients may develop respiratory failure requiring intubation, so a major concern is determining who requires ICU-level monitoring and whether intubation should be performed. Ideally it would be possible to predict with 100% accuracy which patients would require intubation, allowing pre-emptive elective intubation. In reality such prediction is impossible, so we are often forced to carefully observe patients in the ICU until they declare themselves.

GBS vs Myasthenia Gravis vs MND

Comparing Guillain-Barré Syndrome (GBS), Myasthenia Gravis (MG) and Motor neurone disease (MND)

Management of Myasthenia Crisis in the ED

Myasthenia gravis is the most common disorder of neuromuscular transmission. The disease can manifest as a combination of weakness in ocular, bulbar, and most importantly respiratory muscles. Myasthenia gravis is disease of the neuromuscular junction, in which autoantibodies are directed against nicotinic acetylcholine receptors (AChR) located on the postsynaptic end plate.

Myasthenia gravis & myasthenic crisis

Don't assume that a dyspneic patient with myasthenia gravis is necessarily having a myasthenic crisis: these patients may also have any other cause of respiratory failure (e.g. pneumonia, heart failure).

Myasthenia Gravis and Crisis

Generalized weakness is the most common symptom, typically of the proximal muscles, neck extensors, and facial/bulbar muscles (diplopia, ptosis, dysphagia, dysarthria). Ptosis is often the first symptom.

Podcast # 437 : Myasthenia Gravis

MG was historically diagnosed with the Tensilon test but now often by EMG. Treatment of MG crisis involves plasma exchange and IVIG. Those in crisis often require intubation and ICU admission.

Rapid Review: Myasthenia Gravis

It any patient with known myasthenia gravis, clinicians should perform a careful respiratory exam. Pulmonary function testing is generally recommended. If pulmonary function testing is not feasible, one could use the single breath test: ask the patient to take a single breath and then count as high as possible before needing another breath. Getting to 40-50 words is normal. Patients who are unable to count higher than 20 should be considered for ventilatory support.

There is No Crisis: Myasthenia Gravis

Myasthenia Gravis, Myasthenia Gravis… you haven’t seen someone with this since med school, and haven’t thought about it much since then either. You feel like you know nothing about it, but thankfully you have me, the little subconscious voice in your head that was actually semi-listening to that lecture on Myasthenia Gravis (MG) two weeks ago in conference: it’s the most common neuromuscular disorder we know of, it usually affects women earlier than it affects men, like 3rd versus 6th decade, and it is autoimmune.

Resources

Emergency Medicine Guidewire

MC = MG patient in respiratory distress. 15-20% of MG patients will undergo crisis requiring emergency intervention.

Life in the Fastlane

Specific Therapies, cholinesterase inhibitors: pyridostigmine, rivastigmine, plasma exchange, IVIG...