Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, drooping eyelids, trouble talking, and trouble walking. Onset can be sudden. Those affected often have a large thymus or develop a thymoma.Myasthenia gravis is an autoimmune disease of the neuro-muscular junction which results from antibodies that block or destroy nicotinic acetylcholine receptors (AChR) at the junction between the nerve and muscle. This prevents nerve impulses from triggering muscle contractions. Most cases are due to immunoglobulin G1 (IgG1) and IgG3 antibodies that attack AChR in the postsynaptic membrane, causing complement-mediated damage and muscle weakness. Rarely, an inherited genetic defect in the neuromuscular junction results in a similar condition known as congenital myasthenia. Babies of mothers with myasthenia may have symptoms during their first few months of life, known as neonatal myasthenia. Diagnosis can be supported by blood tests for specific antibodies, the edrophonium test, or a nerve conduction study.MG is generally treated with medications known as acetylcholinesterase inhibitors, such as neostigmine and pyridostigmine. Immunosuppressants, such as prednisone or azathioprine, may also be used. The surgical removal of the thymus may improve symptoms in certain cases. Plasmapheresis and high-dose intravenous immunoglobulin may be used during sudden flares of the condition. If the breathing muscles become significantly weak, mechanical ventilation may be required.
A pulmonary consolidation is a region of normally compressible lung tissue that has filled with liquid instead of air. The condition is marked by induration (swelling or hardening of normally soft tissue) of a normally aerated lung. It is considered a radiologic sign. Consolidation occurs through accumulation of inflammatory cellular exudate in the alveoli and adjoining ducts. The liquid can be pulmonary edema, inflammatory exudate, pus, inhaled water, or blood (from bronchial tree or hemorrhage from a pulmonary artery). Consolidation must be present to diagnose pneumonia: the signs of lobar pneumonia are characteristic and clinically referred to as consolidation. Signs
Signs that consolidation may have occurred include:

Expansion of the thorax on inspiration is reduced on the affected side
Vocal fremitus is increased on the affected side
Percussion is dull in the affected area
Breath sounds are bronchial
Possible medium, late, or pan-inspiratory crackles
Vocal resonance is increased. Here, the patients voice (or whisper, as in whispered pectoriloquy) can be heard more clearly when there is consolidation, as opposed to the healthy lung where speech sounds muffled. A pleural rub may be present. A lower PAO2 than calculated in the alveolar gas equation

Diagnosis
Radiology
Typically, an area of white lung is seen on a standard X-ray. Consolidated tissue is more radio-opaque than normally aerated lung parenchyma, so that it is clearly demonstrable in radiography and on CT scans. Consolidation is often a middle-to-late stage feature/complication in pulmonary infections. See also
Pulmonary infiltrate

References


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