Lambert Eaton Syndrome is a very rare paraneoplastic syndrome that is related to but different to myasthenia gravis.
- Lambert Eaton Syndrome is associated with autoantibodies against voltage gated calcium ion channels, required for release of acetyl choline
- Myasthenia Gravis is associated with autoantiboies against the acetylcholine receptor on the muscular side of the neuromuscular synapse, leading to impaired response to acetyl choline
It is most commonly seen in association with small cell lung cancer (85% of cases).
Presenting symptoms are proximal muscle weakness (80%), with ocular symptoms usually not present at diagnosis. This helps to distinguish the condition from myasthenia gravis which usually presents with ocular symptoms in addition to muscle weakness. Muscle weakness improves with activity due to increasing levels of acetyl choline in the neuromuscular junction.
Treatment is of the underlying malignancy, which is not always possible. Symptomatic treatment involves the use of 3,4-DAP which promotes depolarization of calcium ion channels and enhances the release of ACh. Immunological therapy is also effective in some cases. Prednisolone is marginally effective. Intravenous gammaglobulin is one proven therapy but remains expensive.