Eaton Lambert Syndrome

Eaton Lambert Syndrome may be associated with small-cell carcinoma, sometimes developing before the tumor is diagnosed, and occasionally occurs with certain autoimmune diseases. There is defective release of acetylcholine in response to a nerve impulse, and this leads to weakness, especially of the proximal muscles of the limbs. As is not the case in myasthenia gravis, however, power steadily increases with sustained contraction. The diagnosis can be confirmed electrophysiologically, because the muscle response to stimulation of its motor nerve increases remarkably if the nerve is stimulated repetitively at high rates, even in muscles that are not clinically weak.

Lambert-Eaton myasthenic syndrome (LEMS) is a rare condition in which weakness results from an abnormality of acetylcholine (ACh) release at the neuromuscular junction It is an immune-mediated, myasthenia-like syndrome of muscle weakness, characterized by diminished release of acetylcholine from the motor nerve terminal. LEMS is known to be associated with small cell lung cancer. It may also be associated with cancers such as lymphoma , non-Hodgkin's lymphoma, T-cell leukemia, non-small cell lung cancer, prostate cancer , and thymoma . Disorders in which the neuromuscular junction malfunctions include myasthenia gravis, botulism, and Eaton-Lambert syndrome. In most cases, the cancer is discovered within the first 2 years after onset of LEMS and, in virtually all cases, within 4 yearsElectromyography shows increased evoked potentials after repeated galvanic stimulation (the opposite occurs in myasthenia gravis). . Symptoms include muscle weakness, a tingling sensation in the affected areas, fatigue, and dry mouth. LEMS is closely associated with cancer, in particular small cell lung cancer. For example, some of these substances prevent the normal breakdown of acetylcholine after the nerve impulse has been transmitted to the muscle.

The primary physiological disorder in the L ambert- E aton m yasthenic s yndrome (LEMS) is a reduced release of the neurotransmitter acetylcholine from the nerve terminals into the synaptic gap60% of patients have small cell lung carcinoma. The usual age of onset in between 50 and 60 years of age. Men are affected more than women. These plates contain receptors that enable the muscle to respond to acetylcholine, the chemical messenger (neurotransmitter) released by the nerve to transmit a nerve signal across the neuromuscular junction. In patients with LEMS who have SCLC or other cancer, cancer cells presumably contain antigens that mimic VGCC and induce production of VGCC antibodies. The primary symptom of LEMS is muscular weakness or paralysis that varies in intensity and location throughout the body. The disruption of electrical impulses is associated with antibodies produced as a consequence of this autoimmunity. Serum from patients with Eaton-Lambert syndrome contains circulating IgG antibodies that block the voltage-dependent calcium channels in the terminals of normal motor nerve fibers.

Causes of Eaton Lambert Syndrome

The common causes of Eaton Lambert Syndrome :

• All patients with LEMS who have associated SCLC have a history of long-term smoking.
• Infant botulism develops in infants who eat food containing spores of the bacteria rather than previously formed toxins
• There is muscle weakness associated with disturbed communication between nerves and muscles.
• In myasthenia gravis, the neurotransmitter acetylcholine (the chemical that transmits impulses between nerves and muscles) is blocked by antibodies to its receptor.
• This autoimmune reaction is caused by antibodies that a patient produces in response to small cell lung cancer, or one of the other cancers associated with LEMS.
• Adult intestinal colonization botulism also results from eating food containing spores of the bacteria, but it occurs in older children and adults who have an intestinal disorder (such as colitis) or who have recently had surgery on the intestine.

Symptoms of Eaton Lambert Syndrome

Some are common symptoms of Eaton Lambert Syndrome :

• Need to use hands to arise from sitting or lying positions
• Swallowing difficulty , gagging, or choking
• Blood pressure abnormalities
• Dry mouth, eyes, or skin
• Eyelid drooping or double vision (25% of individuals)
• Weakness of the upper legs and upper arms that gets worse over time

Treatment of Eaton Lambert Syndrome

• In the rare case of respiratory distress or failure, treat as in any other patient: initiate supplemental oxygen; secure intravenous (IV) access; and intubate, if indicated.
• Medications can also include anticholinesterase medications such as Neostigmine or Pyridostigmine.
• If necessary to intubate, the use of neuromuscular blocking agents may further exacerbate the weakness and have prolonged effects.
• anticholinesterases are not helpful
• The primary goal of treatment is to identify and treat any tumors or other underlying disorders. Plasmapheresis, where blood plasma is removed and replaced with fluid, may improve symptoms.
• there is not the initial steroid-induced weakness that may be seen in myasthenia gravis
• Medications can also include anticholinesterase medications such as Neostigmine or Pyridostigmine. 3, 4-diaminopyridine is a medicine that increases acetylcholine release from the nerves and helps keep the electrical nerve action working for longer.

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