Lambert-Eaton syndrome
Síndrome de Eaton-Lambert
CategoryDefinition
Lambert-Eaton myasthenic syndrome, 20 times as rare as acetylcholine receptor positive myasthenia gravis with a prevalence of 3.42 per million, is an immune-mediated disease of the neuromuscular junction. Clinically the disease is characterised by proximal weakness of the legs. In most patients, the weakness extends to other muscles including the oculobulbar ones. Autonomic symptoms (dry mouth, erectile dysfunction, constipation) are frequent. Tendon reflexes are reduced. Repetitive nerve stimulation shows low compound muscle action potentials, decrement > 10% at low frequency and increment > 100% after maximum voluntary contraction at high frequency.
Diagnostic Criteria
Signs & symptoms: Progressive weakness that does not usually involve the respiratory muscles and the muscles of facial expression and if these muscles are involved, the involvement is not as severe as in myasthenia gravis. In contrast to myathenia gravis, symptoms of Lambert-Eaton syndrome tend to be worse in the morning and improve with exercise and nerve stimulation. The proximal parts of the legs and arms are predominantly affected. Many patients have autonomic symptoms. Paraneoplastic in about 2/3 of patients.