Lambert Eaton Myasthenic syndrome

Question 1

What is Lambert Eaton Myasthenic syndrome (LEMS) ?

Answer 1

Progressive muscle weakness with increased use due to an abnormal immune response.

Question 2

What is the pathophysiology behind Lambert Eaton Myasthenic syndrome?

Answer 2

The immune system produces antibodies against voltage gated calcium channels at the presynaptic terminals of the neuromuscular junction. This causes less ACh to be released into the synapse, hence decreasing firing action potentials and triggering muscle contraction.

Question 3

What causes Lambert Eaton Myasthenic syndrome?

Answer 3

• Cancers - particularly small cell lung cancer
• can be autoimmune

Question 4

How does Lambert Eaton Myasthenic syndrome present?

Answer 4

Symptoms slowly develop and are worse with activity
- mainly affecting proximal muscles
- diplopia (extraocular muscle weakness)
- ptosis
- weakness in facial movements
- difficulty swallowing
- slurred speech
- autonomic dysfunction (dry mouth, dizziness etc.)
- reduced tendon reflexes

Question 5

How is Lambert Eaton Myasthenic syndrome treated?

Answer 5

• diagnose and treat any underlying malignancy
• amifampridine - allows more ACh to be released
• immunosupressants
• IV immunoglobulins
• plasmapheresis