Myasthenia gravis is an autoimmune disease characterized by autoantibodies against the acetylcholine (ACh) receptor of the neuromuscular junction, resulting in muscular weakness predominantly affecting the facial muscles. Females are affected more frequently than males.
• Extraocular muscle weakness may lead to ptosis and diplopia; the weakness worsens with repeated contractions.
• Respiratory muscle involvement may lead to death.
• There is an association with thymic hyperplasia and thymomas.
Treatment is anticholinesterase agents, steroids, and thymectomy.
Lambert-Eaton myasthenic syndrome frequently arises before a diagnosis of cancer is made, often in cases of small cell lung cancer. Patients report dry mouth and proximal muscle weakness. Autoantibodies are directed against presynaptic calcium channels of the neuromuscular junction. Treatment is immunotherapy and cancer treatment, if indicated.