Eaton-Lambert syndrome is another autoimmune disorder of the neuromuscular junction. The patient's immune system produces antibodies against the calcium channel at the nerve ending of the neuromuscular junction. With the alteration in calcium channels, appropriate levels of acetylcholine are not released and the patient develops weakness and fatigability.
Despite differences in the mechanism of disease, the symptoms of Eaton-Lambert syndrome may be similar to those of myasthenia gravis with the exception that in Eaton-Lambert the eye muscles are frequently spared and the proximal muscles are more prominently involved. The diagnosis is suspected by the clinical picture and confirmed by the presence of a transient increment of the muscle action potentials on repetitive nerve stimulation. At the present time commercial antibody tests are not available for the Eaton-Lambert syndrome. The muscle biopsy is usually not of diagnostic help in this syndrome.
A very important part of the diagnostic workup of Eaton-Lambert syndrome is related to the observation that almost half of the patients have or may develop an underlying cancer. Many patients have their cancer diagnosed as part of the workup of their weakness. The most commonly diagnosed cancer is small cell cancer of the lungs. The most effective treatment of Lambert-Eaton syndrome is the removal and effective treatment of cancer whenever diagnosed. Other modes of treatment with various immunosuppressants are not as effective as in myasthenia gravis. The most rewarding available and non-investigational therapy is the use of intermittent plasmapheresis.