What is the prognosis of Lambert-Eaton myasthenic syndrome (LEMS)?

Updated: May 23, 2019
  • Author: David E Stickler, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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The prognosis is often difficult to assess. [3] It is largely determined by the presence and type of any underlying cancer, the presence and severity of any associated autoimmune disease, and the severity and distribution of weakness. In addition, patients with rapidly progressive symptoms usually have more severe disease.

The main problem created by LEMS is the progressive weakness that affects everyday activities and general quality of life. LEMS does not seem to affect the respiratory system as significantly as MG does. In most patients, weakness does not severely affect vital muscles. Maximum severity usually becomes established within several months of symptom onset.

In most cases, therapy with agents such as 3,4-diaminopyridine (DAP) may help to relieve symptoms partially, but usually symptoms progress over time. Without treatment, weakness and dysfunction do not usually vary. Exceptions are during periods of exacerbation induced by intercurrent illness or by medications that impair neuromuscular transmission.

Eventually, the weakness caused by LEMS can have profound consequences. However, death often results from the underlying malignancy. The diagnosis of LEMS frequently heralds cancer. This association is important in overall morbidity, since there is a very short survival time with SCLC.

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