Highlights & Basics
- Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder of the neuromuscular junction.
- LEMS occurs either as a paraneoplastic disorder in association with an underlying cancer (CA-LEMS), or without cancer and as part of a more general autoimmune state (NCA-LEMS).
- Symptoms include insidious and gradual onset of fatigue, weakness, and a dry mouth.
- Clinical findings include proximal muscle weakness in hip girdle and thigh muscles; absent or reduced tendon reflexes that may facilitate after brief exercise; and dilated, poorly reactive pupils.
- Serum P/Q-type voltage-gated calcium-channel antibodies are usually present. Electrophysiologic studies usually demonstrate decremental responses to low-frequency repetitive nerve stimulation, and may also exhibit postactivation facilitation of >100%.
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AAEM Quality Assurance Committee, American Association of Electrodiagnostic Medicine. Practice parameter for repetitive nerve stimulation and single fiber EMG evaluation of adults with suspected myasthenia gravis or Lambert-Eaton myasthenic syndrome: summary statement. Muscle Nerve. 2001 Sep;24(9):1236-8.[Abstract][Full Text]
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