Understanding the disorder and its importance
Myasthenia gravis (MG) is an autoimmune neuromuscular disorder characterized by weakness and rapid fatigue of voluntary muscles. In MG, antibodies interfere with the communication between nerves and muscles, specifically at the neuromuscular junction. While more common in adults, paediatric MG does occur and can significantly impact a child’s daily functioning and quality of life. Understanding this condition is crucial because proper diagnosis and management can dramatically improve outcomes. MG can affect various muscle groups, potentially impacting vital functions like breathing and swallowing, making early recognition and treatment essential.
Signs and symptoms
The hallmark of myasthenia gravis is fluctuating muscle weakness that worsens with activity and improves with rest. In children, common symptoms include ptosis (drooping eyelids), diplopia (double vision) and facial weakness, often presenting as a ‘snarl’ when smiling. Limb weakness may also occur, typically affecting proximal muscles more than distal ones. Some children experience difficulty swallowing, speaking or breathing. Symptoms often worsen as the day progresses or after prolonged activity. In severe cases, myasthenic crisis can occur, leading to respiratory failure. It’s important to note that symptoms can vary widely between individuals and may fluctuate in severity over time.
When to seek neurological assessment
Neurological assessment should be sought if a child exhibits unexplained, fluctuating muscle weakness, particularly if it affects the eyes, face, or swallowing. Persistent drooping eyelids, double vision or difficulty speaking or chewing that worsens with activity are key indicators. Any sudden worsening of symptoms, especially if affecting breathing, requires immediate medical attention. Additionally, if a child shows signs of generalised weakness or fatigue that cannot be explained by other factors, evaluation for MG should be considered.
Investigation and treatment strategies
Diagnosis of myasthenia gravis involves a combination of clinical examination, specialised tests and laboratory studies. The neurological examination typically includes tests of muscle strength and fatigue. Specific diagnostic tests may include the edrophonium test (Tensilon test), repetitive nerve stimulation studies and single-fibre electromyography (EMG). Blood tests to detect acetylcholine receptor antibodies or muscle-specific kinase (MuSK) antibodies are crucial. Imaging studies like chest CT may be performed to evaluate for thymic abnormalities, as MG is sometimes associated with thymus gland issues.
Treatment strategies for paediatric MG are multifaceted and often require a combination of approaches. Acetylcholinesterase inhibitors such as pyridostigmine are typically the first-line treatment, helping to improve muscle strength by increasing acetylcholine availability at the neuromuscular junction. In more severe cases or when symptoms are not adequately controlled, immunosuppressive therapies may be necessary. These can include corticosteroids, azathioprine, mycophenolate mofetil or other immunomodulating agents.
For acute exacerbations or myasthenic crises, intravenous immunoglobulin (IVIG) or plasma exchange may be used to provide rapid improvement. In some cases, particularly if there’s evidence of thymic abnormalities, thymectomy (surgical removal of the thymus gland) might be considered, although this is less common in paediatric patients than in adults.
Supportive care is also crucial. This may include occupational therapy to help with daily activities, speech therapy if bulbar muscles are affected, and respiratory support if needed. Regular follow-up with a neurologist is essential to monitor symptoms, adjust medications and manage any side effects of treatment.
Patient and family education is an important aspect of management, including guidance on recognising worsening symptoms and understanding potential triggers like infections or certain medications. Long-term management focuses on achieving remission or minimal manifestation status while minimising medication side effects. With proper treatment and management, many children with MG can lead active, fulfilling lives, although ongoing medical care is typically necessary.
