Lambert-Eaton myasthenic syndrome (LEMS) is an uncommon disorder of neuromuscular junction transmission with the primary clinical manifestation of muscle weakness. Knowledge of subtle clinical features and laboratory abnormalities that accompany LEMS permits the early identification of the disorder. Early recognition of LEMS is particularly important because of its strong association with small cell lung cancer (SCLC). Although LEMS can occur at any point in the course of SCLC, it may serve as a marker for early disease, and thus allow more effective treatment of this malignancy.
This topic will review treatment for LEMS. The clinical features and diagnosis of this disorder are discussed separately. (See "Clinical features and diagnosis of Lambert-Eaton myasthenic syndrome".)
EVALUATION FOR MALIGNANCY
The aggressive search for a primary underlying malignancy in patients with any risk factors for small cell lung is central to the management of patients with Lambert-Eaton myasthenic syndrome (LEMS). (See "Clinical features and diagnosis of Lambert-Eaton myasthenic syndrome".)
Small cell lung cancer (SCLC) is the most common associated tumor in patients with LEMS. Although available evidence suggests that early diagnosis does not confer longer survival in SCLC, there is some evidence that the presence of LEMS does imply a better prognosis [1,2].
The role of evaluating patients for occult SCLC was illustrated by a series of 100 patients with LEMS seen in a neurology clinic between 1998 and 2006 . With a minimum follow-up of three years, 54 patients had been diagnosed with SCLC. Overall, 92 percent of those with SCLC were diagnosed within three months and 96 percent within one year of their evaluation for LEMS. The most useful screening procedure was computed tomography (CT) of the thorax, which was more sensitive than routine chest x-ray (sensitivity 93 versus 51 percent) . Positron emission tomography (PET) was useful in selected cases and should be considered for any patient at the initial workup in whom the chest CT is nondiagnostic. (See "Computed tomographic and positron emission tomographic scanning of pulmonary nodules" and "Pathobiology and staging of small cell carcinoma of the lung".)