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A grave disease: Myasthenia Gravis

Diagnosis & Treatment - This goes way beyond the ED, as electrophysiologic studies and autoantibody testing are needed. The ice pack test is helpful at the bedside for patients with ptosis or in those with symptoms of diplopia. Basically, neuromuscular transmission is better at lower temperatures, so by applying an ice pack for 2 minutes to orbits, ptosis should immediately improve once the ice pack is removed. The test is 80% sensitive, but its predictive value has never been assessed. Edrophonium is no longer available in the US so there’s no point in discussing this. Patients having symptomatology consistent with myasthenia gravis should all be admitted for an expedited workup.

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Articles of Interest

MG Emergencies

MG FLARE or exacerbation describes a time when you have weakness in some or all the muscles in your body, but you do not need assistance to breath. MG flares vary from person to person but may include worsened double vision, slurred speech, increased arm weakness, falling, unsteady walking, and difficulty swallowing. Many muscles throughout the body may weaken during an MG exacerbation, but myasthenic crisis refers specifically to severe, potentially life-threatening weakness of respiratory muscles. Myasthenic crisis typically develops after days to weeks of worsening symptoms. Rarely, MG crisis can develop more quickly. It is important to seek medical care immediately when symptoms of possible MG crisis are present.

A Practical Approach to Managing Patients With Myasthenia Gravis—Opinions and a Review of the Literature

Pyridostigmine is by far the most commonly used symptomatic therapy. This is an acetylcholinesterase inhibitor which blocks the degradation of acetylcholine at peripheral cholinergic synapses, including the neuromuscular junction (NMJ). However, with longstanding or severe disease this pharmacological compensation may be insufficient and there may be minimal clinical effect.

Current Treatment of Myasthenia Gravis

Myasthenia gravis (MG) is the most extensively studied antibody-mediated disease in humans. Substantial progress has been made in the treatment of MG in the last century, resulting in a change of its natural course from a disease with poor prognosis with a high mortality rate in the early 20th century to a treatable condition with a large proportion of patients attaining very good disease control.

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.

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.

Ice pack test—an useful bedside test to diagnose myasthenia gravis

Ice pack test can be done by taking baseline eyelid measurement. Ice pack is then applied for 2–5 min and the eyelid is re-measured after that. If there is improvement of 2 mm or more, it’s considered a positive test. The test is thought to be sensitive and specific for myasthenia gravis, where it has no effect on ptosis from other causes.

Intravenous immunoglobulin for myasthenia gravis

In exacerbation of myasthenia gravis, one RCT of IVIg versus placebo showed some evidence of the efficacy of IVIg and two did not show a significant difference between IVIg and plasma exchange. Another showed no significant difference in efficacy between 1 g/kg and 2 g/kg of IVIg. A further, but underpowered, trial showed no significant difference between IVIg and oral methylprednisolone. In chronic myasthenia gravis, there is insufficient evidence from RCTs to determine whether IVIg is efficacious.

IVIG for Myasthenia Gravis

Without proper medical attention, MG can be fatal. IVIG is administered when there is a need for a prompt response, often while waiting for other medications to take effect. It can also be used as a “rescue” treatment if there is an acute relapse of symptoms. When other therapies are not effective in managing symptoms and chronic relapses of symptoms occur, IVIG may be prescribed as maintenance therapy. Given regularly, IVIG maintains proper immune function and helps prevent the development of new antibodies that would otherwise interfere with muscular contraction.

IVIG, Plasma Exchange, and Emerging MG Treatments

IVIg can be used as a rescue therapy or as a maintenance treatment. The first time you get an IVIG treatment, you receive a loading dose based on your weight. That dose can be divided over 1 to 5 days, depending on your health and situation. When administered over more days, fewer side effects are likely. When IVIg is used as a maintenance treatment, a smaller booster dose can be administered every 2 to 8 weeks.

Medications in Myasthenia Gravis

The emergency physician should be careful in prescribing new medications to patients with MG, as that can precipitate a myasthenic crisis (and therefore cause significant morbidity and mortality).

Medicine's Subtle Art Gives A Man The Chance To Breathe Again

Doctors treat myasthenia with drugs that improve the transmission of nerve impulses and suppress the immune system. But the disease is rare enough that many doctors have never seen a case.

Momenta Pharma drug improves symptoms in patients with myasthenia gravis

Momenta Pharmaceuticals reported Monday that in a mid-stage clinical trial, an experimental medicine significantly improved the symptoms of patients with generalized myasthenia gravis, a rare neuromuscular disease.

Myasthenia Gravis

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

Myasthenia gravis & myasthenic crisis

Place ice pack over patient's eye that is affected with ptosis or ophthalmoparesis for two minutes. Improvement following ice supports a diagnosis of myasthenia gravis. Test is cheap, safe, noninvasive – and surprisingly sensitive (~90%) and specific (~80%).

Myasthenia gravis: the fatigable, fluctuating, descending neuromuscular disease

Physical Exam: provocative testing is key to the provisional diagnosis of myasthenia – prolonged upgaze and the ice pack test.

Oh Me Nerves! A Neurology Medley

Recognize the diagnosis, can often be forgotten especially if it is the initial presentation of the disease.

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

Myasthenia gravis is characterized by fatigable muscle weakness. Any muscle group can be involved, but the initial presentation typically involves the ocular muscles, with diplopia and ptosis. Weakness is usually worse at the end of the day, and symptoms can also be exacerbated by other stressors, such as heat, infections, surgery, and menstruation. The symptoms tend to fluctuate with time, which is one reason the diagnosis is often missed initially. In patients with ptosis, if application of ice to the eye for 3 minutes improves the ptosis, that finding indicates myasthenia gravis with a sensitivity and specificity both >90%.

The Ice Test in Myasthenia Gravis: Who Should Do it, When, and Why?

A prospective study supports the value of this test, although confirmatory clinical testing must be done after a positive finding.

Treatment of Myasthenia Gravis Exacerbation With Intravenous Immunoglobulin

The results of this trial comparing IV immunoglobulin infusion of 2 g/kg during 2 days vs 1 g/kg on 1 day in patients with MG exacerbation demonstrate no statistically significant differences. Furthermore, the results were not different from those reported previously with administration of 0.4 g/kg per day for 5 days.1 Therefore, 1 g/kg may be the best dose for general clinical practice. This may have implications on the cost of IVIG infusion for acute exacerbation of MG.

Woman With Weakness, Diplopia and Dysphagia

Differential diagnosis includes: Guillain-Barré syndrome (GBS), Botulism and Lambert-Eaton myasthenic syndrome.