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Lambert-Eaton myasthenic syndrome: Treatment and prognosis

David H Weinberg, MD
Section Editors
Jeremy M Shefner, MD, PhD
Lisa M DeAngelis, MD, FAAN, FANA
Deputy Editor
John F Dashe, MD, PhD


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 "Lambert-Eaton myasthenic syndrome: Clinical features and diagnosis".)


The first priority in the management of LEMS is to evaluate for a primary underlying malignancy. Treatment of the underlying malignancy may be the only intervention necessary to produce improvement in neurologic symptoms.

Small cell lung cancer — Small cell lung cancer (SCLC) is the most common associated tumor in patients with LEMS. Suspicion for lung cancer is particularly high among patients with a history of smoking who are ≥50 years of age [1]. Population studies have consistently shown that approximately one-half of LEMS cases are associated with a malignancy, which is usually SCLC. In a clinical series that included 50 patients with LEMS, SCLC was present in 21 of 25 patients (84 percent) with cancer [2]. From the perspective of patients who have SCLC, the incidence and prevalence of LEMS are estimated to be approximately 3 percent each [3-5]. (See "Pathobiology and staging of small cell carcinoma of the lung".)

Other malignancies — The other malignancies most convincingly associated with LEMS are lymphoproliferative disorders, including Hodgkin lymphoma [6-8]. LEMS has been rarely associated with atypical carcinoid [9], Merkel cell carcinoma [10], thymic neuroendocrine carcinoma [11], malignant thymoma [12] and neuroblastoma [8].

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Literature review current through: Nov 2017. | This topic last updated: Dec 11, 2017.
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