Myasthenia Gravis

Definition

Myasthenia gravis may causes sporadic but progressive weakness and abnormal fatigability of striated muscles. Symptoms are exacerbated by exercise and repeated movement and treated by anticholinesterase drugs. This disorder affects muscles innervated by the cranial nerves such as face, lips, tongue, neck, and throat but can affect any muscle group.

It's three times more common in women than in men in this age-group; but, after age 40, the incidence is similar in women and men. About 20% of infants born to mothers with myasthenia gravis have transient myasthenia for 2 to 3 weeks. This disease may coexist with immune and thyroid disorders, 15% of patients with myasthenia gravis have thymomas.

Causes of Myasthenia Gravis

Theoretically, antireceptor antibodies block, weaken, or reduce the number of acetylcholine receptors available at each neuromuscular junction, impairing muscle depolarization necessary for movement. The exact cause of myasthenia gravis is unknown. But other various causes may be occur such as:

• Autoimmune response
• Ineffective acetylcholine release
• Inadequate muscle fiber response to acetylcholine.

In addition, certain medications, such as antibiotics, beta-adrenergic blockers, lithium, magnesium, Proscar, verapamil, and quinidine, can exacerbate the disease.

Symptoms of Myasthenia Gravis

Symptoms of this disease include:

• Weak eye closure
• Ptosis, and diplopia from impaired neuromuscular transmission to the cranial nerves supplying the eye muscles
• Skeletal muscle weakness and fatigue
• Increasing through the day but decreasing with rest
• Progressive muscle weakness and accompanying loss of function
• Depending on the muscle group affected that becomes more intense during menses and after emotional stress
• Prolonged exposure to sunlight or cold, or infections
• Blank and expressionless facial appearance and nasal vocal tones secondary to impaired transmission of cranial nerves innervating the facial muscles
• Frequent nasal regurgitation of fluids and difficulty chewing and swallowing from cranial nerve involvement
• Drooping eyelids from weakness of facial and extra ocular muscles
• Respiratory muscle weakness that's possibly severe enough to require an emergency airway and mechanical ventilation.

Other complications of myasthenia gravis may include:

• Respiratory distress
• Pneumonia
• Aspiration
• Myasthenic or cholinergic crisis.

Treatment of Myasthenia Gravis

If you have this disease, then you should be use Possible treatment such as:

• For the treatment of this disease, you can use anticholinesterase drugs, such as neostigmine and pyridostigmine, to counteract fatigue and muscle weakness and allow about 80% of normal muscle function aess effective as disease worsens.
• Another treatment of this disease immunosuppressant therapy with corticosteroids, azathioprine amuran, cyclosporine (Sandimmune) and cyclophosphamide (Cytoxan) used in a progressive fashion to decrease the immune response toward acetylcholine receptors at the neuromuscular junction.
• You can also use thymectomy to remove thymomas and possibly induce remission in some cases of adult-onset myasthenia, tracheotomy, positive-pressure ventilation, and vigorous suctioning to remove secretions for treatment of acute exacerbations that cause severe respiratory distress.