Also known as myasthenic syndrome, Lambert-Eaton syndrome is an autoimmune disease of neuromuscular transmission that is most commonly associated with small cell carcinoma of the lung. Pathophysiology: Antibodies against presynaptic voltage gated calcium channels develop. These antibodies are IgG mediated. These channels control the release of acetylcholine at the NMJ, and the antibodies lead to decreased acetylcholine release. The result is proximal muscle weakness that typically begins in the lower extremities but may spread to involve upper limbs and eventually the respiratory muscles. In Lambert Eaton syndrome, muscle weakness improves with repeated effort. LE syndrome versus MG: •Receptors: LE syndrome affects presynaptic release of acetylcholine. Myasthenia gravis affects postsynaptic nicotinic acetylcholine receptors. •Muscle group affected: LE syndrome affects primarily proximal muscles, while MG can affect any skeletal muscle. •Effects of NMBs: Patients with Lambert-Eaton are sensitive to both depolarizing and nondepolarizing NMBs. Note that in myasthenia gravis, patients are relatively resistant to succinylcholine. NMBAs should be given only in small increments if used at all. •Effect of repeated movement: In LE syndrome, repeated muscle movement leads to improvement in motion, while in myasthenia gravis, repeated movement leads to muscle weakness. Barash: Clinical Anesthesia, ed 6, p 627-8 Morgan: Clinical Anesthesiology, ed 4, p 819
Posted on: Thu, 27 Jun 2013 19:27:22 +0000
Trending Topics
Recently Viewed Topics
© 2015