Lambert-Eaton myasthenic syndrome

Background

• Autoantibodies against Ca channels of axon nerve terminals responsible for ACh release
• Epidemiology
  • Predominantly a disease a/w older men w/ history of cigarette smoking and lung cancer
    • 50% of pts have concurrent small-cell lung cancer
  • Syndrome can precede detection of malignancy by several years

Clinical Features

• Fluctuating symmetric weakness and fatigue, esp of proximal leg muscles
• Improvement in strength with sustained or repeated exercise (in contrast to MG)
  • Lambert sign: handshake strength increases over several seconds
• Myalgias
• Muscle stiffness (especially in hip and shoulders)
• Paresthesias
• Metallic taste
• Autonomic symptoms (dry mouth, impotence)
• Eye movements are unaffected
• Sensory examination normal

Treatment

• Supportive (progression to respiratory or bulbar failure is rare)
• Acetylcholinesterase inhibitors (e.g. pyridostigmine) can improve symptoms

Disposition

• Admission required when infectious complications occur or when severe disability requires inpatient immunotherapy

See Also

• Myasthenia Gravis

Source

Tintinalli