What is seronegative myasthenia?

Importance Double-seronegative myasthenia gravis (dSNMG) includes patients with myasthenia gravis (MG) without detectable antibodies to the nicotinic acetylcholine receptor (AChR) or to muscle-specific tyrosine kinase (MuSK). The lack of a biomarker hinders the diagnosis and clinical management in these patients.

What is the most accurate test for myasthenia gravis?

The anti–acetylcholine receptor (AChR) antibody (Ab) test is reliable for diagnosing autoimmune myasthenia gravis (MG). It is highly specific (as high as 100%, according to Padua et al).

What is myasthenia gravis misdiagnosed?

In the absence of ocular symptoms and signs, limb girdle myasthenia could be misdiagnosed as muscular dystrophy.

How is seronegative myasthenia gravis diagnosed?

Nerve conduction studies may be a better tool to diagnose seronegative MG. These tests measure the speed and strength of the electrical activity in the nerves and neuromuscular junction. Electromyography (EMG) and repetitive nerve stimulation (RNS) are the most common tests.

What is Lambert Eaton syndrome?

Lambert-Eaton myasthenic syndrome (LEMS) is a very rare condition that affects the signals sent from the nerves to the muscles. It means the muscles are unable to tighten (contract) properly, resulting in muscle weakness and a range of other symptoms.

What is myasthenia gravis compared to?

Myasthenia gravis is often misdiagnosed as a different neurological condition with similar symptoms, such as MS or ALS. With this in mind, the following tests may be used to determine if symptoms are due to myasthenia gravis or another condition: Physical exam.

How do you rule out myasthenia gravis?

The main test for myasthenia gravis is a blood test to look for a type of antibody (produced by the immune system) that stops signals being sent between the nerves and muscles. A high level of these antibodies usually means you have myasthenia gravis.

Can you have myasthenia gravis with a normal EMG?

The nerve conductions and EMG studies are usually normal in myasthenia gravis, but the repetitive stimulation of a nerve may demonstrate decrements of the muscle action potential. The muscle biopsy is usually not of diagnostic help in typical myasthenia gravis.