Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 24-34: Disorders of Neuromuscular Transmission + Key Features Download Section PDF Listen +++ ++ There is defective release of acetylcholine in response to a nerve impulse, leading to weakness, especially of the proximal muscles of the limbs May be associated with small-cell carcinoma, sometimes developing before the tumor is diagnosed, and occasionally occurs with certain autoimmune diseases (eTable 39–1) ++Table Graphic Jump LocationeTable 39–1.Paraneoplastic syndromes associated with cancer.View Table||Download (.pdf)eTable 39–1. Paraneoplastic syndromes associated with cancer. Hormone Excess or Syndrome Non–Small Cell Lung Cancer Small Cell Lung Cancer Breast Cancer Renal Cell Carcinoma Adrenal Cancer Hepatocellular Carcinoma Gastrointestinal Cancers Plasma Cell Myeloma Lymphoma Thymoma Prostatic Cancer Ovarian Cancer Choriocarcinoma Germ Cell Cancers Endocrine Hypercalcemia ++ ++ ++ ++ ++ + ++ Cushing syndrome + ++ + ++ ++ + SIADH ++ ++ Hypoglycemia + ++ + Gonadotropin secretion + ++ + + + + ++ ++ Hyperthyroidism Hematologic Erythrocytosis ++ + ++ Pure red cell aplasia + ++ Coagulopathy ++ ++ ++ + Thrombophlebitis + ++ ++ + Neurologic Lambert-Eaton myasthenic syndromes + ++ + + + + + Subacute cerebellar syndrome ++ + + + + Sensory motor peripheral neuropathy ++ Stiff man syndrome + Dermatologic Dermatomyositis ++ ++ + + + Acanthosis nigricans + + ++ + Fever ++ ++ ++ + Hypertrophic osteoarthropathy ++ +, reported associated; ++, strong association.SIADH, syndrome of inappropriate antidiuretic hormone. + Clinical Findings Download Section PDF Listen +++ ++ Variable weakness, typically improving with activity Dysautonomic symptoms may also be present A history of malignant disease may be obtained Unlike myasthenia gravis, power steadily increases with sustained contraction + Diagnosis Download Section PDF Listen +++ ++ Electrophysiologic diagnosis: the muscle response to stimulation of its motor nerve increases remarkably after exercise or if the nerve is stimulated repetitively at high rates (50 Hz), even in muscles that are not clinically weak + Treatment Download Section PDF Listen +++ ++ Intravenous immunoglobulin, plasmapheresis and immunosuppressive drug therapy (prednisone and azathioprine), in addition to therapy directed at a tumor Prednisone is usually initiated in a daily dose of 60–80 mg and azathioprine in a daily dose of 2 mg/kg orally Symptomatic therapy includes the use of potassium channel antagonists Amifampridine (15–80 mg/day orally in three divided doses) is approved in the United States and Europe Guanidine hydrochloride (25–50 mg/kg/day in divided doses) is occasionally helpful in seriously disabled patients, but adverse effects of the drug include marrow suppression Response to treatment with anticholinesterase drugs, such as pyridostigmine or neostigmine, is usually disappointing