Lambert-Eaton Myasthenic Syndrome (LEMS)

Understanding LEMS

Lambert-Eaton myasthenic syndrome (LEMS) is a neuromuscular disorder (a condition that affects the nerves and muscles). LEMS occurs when antibodies cause the immune system to disrupt communication between nerves and muscles. LEMS disrupts the nerves' ability to release a chemical (acetylcholine) which is necessary for the muscle to work properly.

Symptoms of LEMS

Symptoms of Lambert-Eaton myasthenic syndrome (LEMS) include slow progressive muscle weakness and fatigue. The patient may also experience frequent muscle aches and cramps. The progressive muscle weakness commonly involves muscles of the hips, legs and shoulders and can sometimes cause significant difficulty in performing everyday activities. Involuntary muscles can also be affected. Other symptoms include blurred vision, drooping eyelids, swallowing problems, dry mouth, constipation or erectile dysfunction.

Diagnosing LEMS

Lambert-Eaton myasthenic syndrome (LEMS) is diagnosed based on clinical symptoms, electromyographic (EMG) testing to measure muscle activity and testing for the presence of autoantibodies against voltage gated calcium channels.

LEMS can be categorized into two different classes

• LEMS associated with small cell lung cancer (about 60% of LEMS patients).
• LEMS without cancer association, also known as non-paraneoplastic Lambert-Eaton myasthenic syndrome.

Treating LEMS

Current treatment targets reduction of symptoms and can include:

• Treatment of lung cancer for those patients with small cell lung cancer.
• Medications to help nerve signals reach the muscles.
• Medications targeted at reducing the number of antibodies, include immune globulin administered into the blood stream intravenously (IVIG), plasmapheresis, corticosteroids and immune suppressive medications such as azathioprine (e.g., Imuran^®), mycophenolate (e.g., CellCept^®), methotrexate and others, or monoclonal antibodies.

Resources:

• Muscular Dystrophy Association USA

Reference:

• LEMS.com