Lambert-Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome is a rare autoimmune disorder that affects calcium channels on the pre-synaptic membrane of the neuromuscular junction. Inhibition of these channels prevents the release of acetylcholine from the presynaptic terminal and postsynaptic terminal secondary stimulation leads to muscle contraction. The clinical picture of the syndrome may be similar to that of myasthenia gravis but there are substantial differences between the pathogenic characters of the two conditions.
The disease is usually seen in older people and children, although adults may also be affected. The incidence is difficult to determine because of the reduced frequency.Major clinical element is found not to involve progressive weakness and respiratory muscles of the facial expression. In patients with eye and facial muscle involvement is not affected so severely as in myasthenia gravis. Also from myasthenia gravis symptoms of this syndrome tend to be more severe in the morning and improves with exercise and nerve stimulation.Proximal part of the legs and arms are predominantly affected.Many patients have symptoms such as dry mouth or impotence autonomous. Reflexes are often reduced or absent.
Syndrome and the disease can be detected as solitary, but 60% is associated with small cell lung cancer. Other associated malignancies are extremely rare. Myasthenic syndrome associated with myasthenia gravis timomul is true that the work tired muscles. Whether alone or dependent cancer syndrome is considered to be of autoimmune origin. I detect autoantibodies against presynaptic calcium channels located in neuromuscular junction and presynaptic release of acetylcholine responsible.Antibodies to open channels and thus prevent release of acetylcholine.
Diagnosis is established by clinical and laboratory evaluation: chest x-ray to determine cancer antibodies anticanale calcium response to repetitive nerve stimulation.
Corticosteroids, azathioprine and 3-4 diaminopiridina are used to treat Lambert-Eaton syndrome with limited success. In some cases with progressive intravenous immunoglobulin and plasmapheresis have been tried. Treatment of lung cancer symptoms resolve.
Pathogenesis and causes:
Lambert Eaton syndrome is a rare condition in which weakness result from an abnormality of acetylcholine release from neuromuscular junction. It is the result of an autoimmune attack against voltage-dependent calcium channels on presynaptic nerve terminal motor. Number issued by Quante nerve impulse is diminished. However due to deposits of acetylcholine presynaptic repetitive stimulation or activation of fast voluntary help to release these reserves will raise the potential for action and will allow the generation of muscle action potential. As neuromuscular transmission is complete in neighboring neuromuscular junctions appears a transient increase in muscle strength. Parasympathetic neurons, sympathetic and enteric are all affected. Clinical phenomenon is noticed by the appearance of previously absent tendon reflex followed by a period of strong muscle contraction.
Cancer is now the onset of weakness or later discovered more than 40% of patients. It is usually a small cell lung cancer but may be associated with lymphosarcoma was done.In, timomul malignant carcinoma of breast, stomach, colon, prostate, bladder, kidney or bile.The following clinical observations suggest an autoimmune etiology: syndrome is frequently associated with autoimmune diseases known, prednisone, plasmapheresis and intravenous administration of human hyperimmune gammaglobulina are effective treatments, acientii Eaton-Lambert syndrome without cancer frequently have high levels of organ-specific autoantibodies.