What are the symptoms of myasthenia gravis?

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Symptoms of Myasthenia Gravis

Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disorder characterized by varying degrees of skeletal muscle weakness. This weakness is caused by an immune response that interferes with the transmission of signals between nerves and muscles at the neuromuscular junction. Below, we explore the primary symptoms associated with MG, categorized by the affected muscle groups.

Ocular Symptoms: Ptosis and Diplopia

One of the earliest and most common manifestations of MG is ocular muscle weakness. This typically presents as ptosis (drooping of one or both eyelids) and diplopia (double vision) . These symptoms are often the first to appear and can be markedly asymmetric, involving several eye muscles. In many cases, ocular symptoms precede generalized muscle weakness by months or even years.

Bulbar Symptoms: Dysarthria, Dysphonia, and Dysphagia

MG frequently affects the muscles involved in speech and swallowing, leading to bulbar symptoms. Patients may experience dysarthria (difficulty speaking), dysphonia (voice changes), and dysphagia (difficulty swallowing) . These symptoms can significantly impact daily activities and quality of life, as they interfere with basic functions such as eating and communicating.

Generalized Muscle Weakness

Generalized muscle weakness in MG can affect various muscle groups, including those in the arms, legs, and neck. This weakness is often more pronounced in proximal muscles (closer to the center of the body) than in distal muscles (further from the center). The severity of muscle weakness can fluctuate throughout the day and typically worsens with activity and improves with rest .

Respiratory Muscle Weakness

In severe cases, MG can affect the respiratory muscles, leading to breathing difficulties. This can result in a myasthenic crisis, a life-threatening condition requiring immediate medical intervention . Respiratory muscle involvement is a critical factor in the overall prognosis of the disease.

Fatigue and Muscle Fatigability

A hallmark of MG is muscle fatigability, where muscle strength decreases with sustained activity. This symptom is often accompanied by central fatigue, characterized by a pervasive sense of physical and mental exhaustion. Fatigue can significantly impair the quality of life and is a common complaint among MG patients.

Variability and Exacerbation

The symptoms of MG are highly variable and can change in severity over time. Patients often experience periods of exacerbation and remission. Factors such as stress, infection, and certain medications can trigger symptom exacerbation .

Conclusion

Myasthenia gravis presents with a range of symptoms primarily characterized by muscle weakness and fatigability. Ocular symptoms like ptosis and diplopia are often the first to appear, followed by bulbar symptoms affecting speech and swallowing. Generalized muscle weakness can impact various muscle groups, and in severe cases, respiratory muscles may be involved, leading to potentially life-threatening complications. Understanding these symptoms is crucial for the timely diagnosis and effective management of MG.