Disease Information for Eaton-Lambert syndrome: Definition

  • An autoimmune disease characterized by weakness and fatigability of proximal muscles, particularly of the pelvic girdle, lower extremities, trunk, and shoulder girdle; There is relative sparing of extraocular and bulbar muscles; CARCINOMA, SMALL CELL of the lung is a frequently associated condition, although other malignancies and autoimmune diseases may be associated; Muscular weakness results from impaired impulse transmission at the NEUROMUSCULAR JUNCTION; Presynaptic calcium channel dysfunction leads to a reduced amount of acetylcholine being released in response to stimulation of the nerve; (From Adams et al, Principles of Neurology, 6th ed, pp 1471)---------------------------------------The Eaton-Lambert syndrome is an immune-mediated, myasthenia-like syndrome with weakness usually affecting the limbs and sparing ocular and bulbar muscles; It is presynaptic, resulting from impaired release of acetylcholine from nerve terminals; An IgG antibody is involved; The syndrome can precede, occur with, or develop after the diagnosis of cancer; It occurs most commonly in men with intrathoracic tumors (70% have small or oat cell lung carcinoma); Symptoms and signs include fatigability, weakness, sometimes

    pain in proximal limb muscles, peripheral paresthesias, dry mouth, impotence, and ptosis; Deep tendon reflexes are reduced or lost; The diagnosis is confirmed by finding an incremental response to repetitive nerve stimulation ; Amplitude of the compound muscle action potential increases > 200% at rates > 10 Hz; Treatment is first directed at the underlying malignancy and sometimes induces remission; Guanidine (initially 125 mg po qid, gradually increased to a maximum of 35 mg/kg), which facilitates acetylcholine release, often lessens symptoms but may depress bone marrow and liver function; Corticosteroids and plasmapheresis benefit some patients; [Adapted from Merck Manual 17th] ----------------------------

    Lambert-Eaton Myasthenic Syndrome, Eaton-Lambert Syndrome,

    Lambert-Eaton Syndrome, Myasthenic Syndrome of Lambert-Eaton; Lambert-Eaton Myasthenic Syndrome (LEMS) is a rare autoimmune disorder characterized by the gradual onset of muscle weakness, especially of the pelvic and thigh muscles; Approximately 60 percent of LEMS cases are associated with a small cell lung cancer, and the onset of LEMS symptoms often precedes the detection of the cancer [nord 2005]------------------------------------------------