Myasthenia gravis – Symptoms, Types & Treatment – Medanta

A chronic autoimmune, neuromuscular condition known as myasthenia gravis results in skeletal muscle weakness that gets worse after periods of exertion and gets better after periods of rest. These muscles control respiration and the movement of various bodily parts, such as the arms and legs.

The Latin and Greek origins of the term myasthenia gravis translate to "grave, or significant, muscle weakness." Myasthenia gravis has no known cure, however, with modern treatments, the majority of cases are not as severe as the name suggests. The available treatments frequently enable people to maintain a relatively high quality of life while controlling symptoms. The majority of those who have the illness have a typical life expectancy.

Myasthenia gravis symptoms

Myasthenia gravis causes muscle weakness that gets worse as the affected muscle is used. Muscle weakness symptoms can come and go because they often go better with rest. Although the symptoms normally worsen within a few years of the disease's inception, they do tend to worsen over time.

The muscles you can actively control can be affected by myasthenia gravis, however, some muscle groups are more frequently impacted than others.

Eyes

The eyelids may drop, and MG may also result in double or hazy vision. Your ocular muscles could also become generally weak.

Face

Your facial expressions could vary as a result of MG in addition to facial paralysis.

You may encounter the following symptoms if MG affects your throat muscles:

Problems speaking

Having trouble breathing

Difficulty chewing or swallowing

Squeaky voice

Neck weakness that makes it challenging to hold your head erect

Chest

You may suffer the following severe and sometimes fatal symptoms when MG attacks the chest muscles:

Emergencies include respiratory failure, which is brought on by diaphragmatic and chest muscle weakness and may produce a myasthenic crisis.

Arms and legs

The muscles in your arms and legs may also be impacted by MG, resulting in the symptoms listed below:

Fatigue

Sluggishness in your arms, hands, and fingers

General issues with leg weakness climbing stairs or lifting things

Not every person will have all of the symptoms, and the level of muscle weakness might vary from day to day. If the symptoms are not treated, they usually get worse over time.

Myasthenia types

There are two basic kinds of myasthenia gravis (MG): generalised and ocular. There are various MG subtypes. Multiple subtypes of MG are possible in individuals. The type and subtypes of a person can influence the treatment plan.

Ocular

The word "eye" is ocular. The muscles that regulate the eyes and eyelids are weak and wear out over time in the ocular myasthenia gravis. Double vision and droopy eyelids may result from this. Approximately 15% of all MG patients have the ocular variant.

Generalized

Eye symptoms frequently start in one muscle group and progressively move to another. This condition is known as generalised MG. The muscles that are most frequently afflicted are those in the arms, legs, and face. One in ten persons with widespread MG will experience breathing-related muscle weakness. A myasthenic crisis is what is known when this occurs.

Refractory MG is the term used to describe myasthenia gravis, which does not respond well to treatment. Myasthenia gravis is only refractory in 15% of MG patients.

Treatment 

a neurological and physical examination A doctor will first go over the patient's medical background and perform a physical examination. During a neurological examination, the doctor will look for impairments in eye movement as well as muscular strength and tone, coordination, and sense of touch.

a test for edrophonium. Edrophonium chloride injections are used during this test to temporarily reduce myasthenic patients' weakness. The medication briefly raises the amounts of acetylcholine at the neuromuscular junction and prevents its breakdown. Usually, it's used to check for ocular muscle weakness.

blood analysis. Acetylcholine receptor antibodies are often abnormally high in the majority of myasthenic Gravis patients. About half of people with myasthenia gravis who do not have acetylcholine receptor antibodies have been shown to have a second antibody, known as the anti-MuSK antibody. This antibody can also be found using a blood test. However, neither of these antibodies is present in some people with myasthenia gravis. These people are said to have myasthenia seronegative (antibody-negative).

Electrodiagnostics. Repetitive nerve stimulation, a diagnostic procedure, uses brief electrical pulses to repeatedly stimulate a person's nerves to fatigue particular muscles. In contrast to muscles from healthy people, muscle fibres in myasthenia gravis and other neuromuscular disorders do not respond to repetitive electrical stimulation as well. The most sensitive test for myasthenia gravis, single fibre electromyography (EMG), finds decreased nerve-to-muscle communication. When other tests fail to reveal abnormalities, EMG can be highly useful in identifying mild cases of myasthenia gravis.

Imaging for diagnosis. A thymoma may be seen during diagnostic imaging of the chest using computed tomography (CT) or magnetic resonance imaging (MRI). 

Tests for pulmonary function. Measuring breathing capacity can assist identify patients who may experience a myasthenic crisis if respiration fails.

The diagnosis of myasthenia gravis is frequently missed or delayed (sometimes up to two years) in those who only have modest weakness or in those whose weakness is limited to a small number of muscles since weakness is a common sign of many different illnesses.