Myasthenia Gravis (MG) is a chronic autoimmune neurological disorder that affects the neuromuscular junction, the point of communication between nerves and muscles. It is characterized by muscle weakness that typically worsens with activity and improves after rest. The severity of muscle weakness may fluctuate considerably throughout the day. The condition can affect the muscles of the eyes, face, swallowing, speech, neck, and limbs. In more severe cases, the respiratory muscles may also be affected. Early diagnosis and appropriate treatment allow most patients with Myasthenia Gravis to achieve significant control of their symptoms and maintain a good quality of life.

Understanding the Neuromuscular Junction in Myasthenia Gravis

For normal muscle contraction to occur, a nerve impulse must be effectively transmitted from the nerve to the muscle. At the neuromuscular junction, acetylcholine is released. This neurotransmitter binds to specific receptors on the surface of the muscle cell, allowing the muscle to become activated. In Myasthenia Gravis, the immune system produces autoantibodies that interfere with this normal communication between the nerve and the muscle. In most patients, antibodies against acetylcholine receptors (AChR antibodies) can be detected.

Other patients may have antibodies against different proteins involved in neuromuscular transmission, including:

• MuSK antibodies
• LRP4 antibodies

There are also patients in whom the commonly tested antibodies cannot be detected despite clinical and neurophysiological findings consistent with Myasthenia Gravis.

Symptoms of Myasthenia Gravis

The characteristic feature of Myasthenia Gravis is easy muscle fatigability and fluctuating muscle weakness. Symptoms may be mild or more pronounced and often vary throughout the day. They may worsen following prolonged muscle activity and improve after rest.

Ocular Symptoms

In many patients, the first symptoms involve the muscles controlling the eyes.

The most common symptoms include:

• drooping of one or both eyelids (ptosis)
• double vision (diplopia)
• difficulty maintaining gaze
• fluctuating weakness of the eye muscles

Ptosis may become more noticeable towards the end of the day or after prolonged use of the eyes. When the disease is limited exclusively to the eye muscles, it is referred to as ocular Myasthenia Gravis.

Generalized Myasthenia Gravis

In some patients, muscle weakness extends beyond the eye muscles.

Generalized Myasthenia Gravis may affect:

• facial muscles
• muscles involved in chewing
• swallowing muscles
• muscles involved in speech
• neck muscles
• muscles of the upper limbs
• muscles of the lower limbs
• respiratory muscles

Patients may experience difficulty holding their head upright, raising their arms, climbing stairs, or standing up from a chair.

Difficulty with Speech, Chewing and Swallowing

When Myasthenia Gravis affects the muscles involved in speech and swallowing, symptoms may include:

• difficulty chewing
• fatigue during meals
• difficulty swallowing
• changes in the voice
• a nasal quality to the voice
• difficulty articulating words clearly
• choking while eating or drinking

These symptoms require particular attention, as severe swallowing difficulties may increase the risk of aspiration.

Factors That May Worsen Myasthenia Gravis

The symptoms of Myasthenia Gravis may fluctuate and, in some cases, can be worsened by:

• infections
• fever
• surgical procedures
• physical exhaustion
• significant stress
• sleep disturbances
• certain medications

Some medications can interfere with neuromuscular transmission and should therefore be used with particular caution in patients with Myasthenia Gravis. For this reason, patients should inform their treating physicians and anesthesiologist about their diagnosis before starting new medications or undergoing a surgical procedure.

Myasthenia Gravis and the Thymus Gland

The thymus gland appears to play an important role in the pathophysiology of Myasthenia Gravis. Some patients have abnormalities of the thymus, such as thymic hyperplasia, while a smaller proportion have a thymoma, a tumor of the thymus gland. For this reason, following a diagnosis of Myasthenia Gravis, imaging of the mediastinum with a CT or MRI scan of the chest is usually performed, depending on the individual case.

Diagnosis of Myasthenia Gravis

The diagnosis of Myasthenia Gravis is made by a neurologist and is based on a combination of the patient's medical history, characteristic clinical presentation, immunological testing, and neurophysiological investigations.

During the neurological examination, the following may be assessed:

• ptosis
• eye movements
• presence of double vision
• strength of the facial muscles
• speech and swallowing
• muscle strength in the neck and limbs
• development of muscle fatigue following repetitive activity

The fluctuating nature of symptoms and worsening of weakness with repetitive activity are important elements of the clinical assessment.

Antibody Tests for Myasthenia Gravis

Blood tests may include testing for:

• acetylcholine receptor antibodies (AChR antibodies)
• MuSK antibodies
• LRP4 antibodies in selected cases

The absence of detectable antibodies does not, by itself, exclude the diagnosis of Myasthenia Gravis.

Electromyography in Myasthenia Gravis

Neurophysiological investigations play an important role in evaluating disorders of neuromuscular transmission.

Testing may include:

Repetitive Nerve Stimulation: Repetitive Nerve Stimulation (RNS) evaluates the muscle response following repeated electrical stimulation of a nerve.

In patients with impaired neuromuscular transmission, a characteristic reduction in the muscle response may be observed.

Single-Fiber EMG: Single-Fiber Electromyography (SFEMG) is a highly sensitive neurophysiological examination used to assess neuromuscular transmission.

It may be used when the diagnosis remains uncertain or when a more specialized assessment of neuromuscular junction function is required.

Treatment of Myasthenia Gravis

The treatment of Myasthenia Gravis is individualized according to:

• severity of the disease
• muscle groups affected
• type of antibodies present
• age of the patient
• presence or absence of a thymoma
• coexisting medical conditions
• response to previous treatments

The aim of treatment is to achieve effective symptom control, restore daily functioning, and prevent serious exacerbations.

Acetylcholinesterase Inhibitors

Pyridostigmine is commonly used for the symptomatic treatment of muscle weakness. By inhibiting the breakdown of acetylcholine, it increases the availability of acetylcholine at the neuromuscular junction and may temporarily improve muscle function. This treatment improves symptoms but does not directly treat the underlying autoimmune mechanism of the disease.

Immunotherapy in Myasthenia Gravis

When control of autoimmune activity is required, corticosteroids and other immunomodulatory or immunosuppressive medications may be used. The choice of treatment depends on the severity of the disease, the need for long-term disease control, and the individual characteristics of the patient.

Newer Targeted Therapies

In recent years, new targeted biological therapies have been developed for specific groups of patients with generalized Myasthenia Gravis.

These treatments target specific mechanisms of the immune system, including:

• the complement system
• the neonatal Fc receptor (FcRn), which influences the levels of pathogenic IgG antibodies

The choice of targeted therapy depends on the type of Myasthenia Gravis, antibody status, disease severity, and response to previous treatments.

Plasma Exchange and Intravenous Immunoglobulin

Plasma exchange (plasmapheresis) and intravenous immunoglobulin (IVIG) may be used when relatively rapid improvement in muscle weakness is required.

They may be used in cases of:

• significant worsening of the disease
• severe swallowing difficulties
• myasthenic crisis
• preparation of selected patients before surgery

The choice between these treatments depends on the patient's clinical condition and individual characteristics.

Thymectomy in Myasthenia Gravis

Thymectomy, the surgical removal of the thymus gland, is an important treatment option for specific groups of patients. When a thymoma is present, surgical assessment is an essential part of management. Thymectomy may also provide therapeutic benefit in appropriately selected patients with generalized Myasthenia Gravis without a thymoma, particularly in patients with acetylcholine receptor antibodies. The decision is made individually in collaboration with the appropriate specialized medical team.

Myasthenic Crisis

A myasthenic crisis is a serious worsening of Myasthenia Gravis in which weakness of the respiratory muscles can lead to respiratory failure.

It is a medical emergency and requires immediate hospital treatment.

Warning symptoms may include:

• increasing shortness of breath
• difficulty swallowing
• inability to manage secretions
• significant worsening of speech
• rapid worsening of generalized muscle weakness

The development of respiratory distress in a patient with Myasthenia Gravis requires immediate emergency medical assessment.

Course and Prognosis of Myasthenia Gravis

The course of Myasthenia Gravis varies considerably between patients. There may be periods of stability, improvement, or worsening of symptoms. With modern treatment options, most patients can achieve significant control of the disease and maintain a high level of daily functioning. Appropriate follow-up is important so that treatment can be adjusted according to the course of the disease.

Neurological Follow-Up of Myasthenia Gravis

Regular neurological follow-up is essential for assessing muscle strength, ocular and swallowing-related symptoms, respiratory function, and response to treatment. Follow-up also allows early recognition of possible deterioration and appropriate adjustment of the treatment strategy. Early diagnosis of Myasthenia Gravis, appropriate neurophysiological and immunological testing, and individualized treatment can significantly contribute to effective disease control and the maintenance of the patient's quality of life.