Eaton-Lambert Syndrome

Background

• Disease of the neuromuscular junction leading to primary presentation of weakness
• Caused by auto-antibodies against the voltage-gated calcium channels at the NMJ

Clinical Features

• Often presents with alteration in gait or difficulty rising from a chair
• Symmetrical muscle weakness and fatiguability often beginning in lower extremities
• Autonomic dysfunction (dry mouth, erectile dysfunction)
• Compared with myastenia gravis, ELS begins with lower extremities weakness and rarely begins with extraocular muscle weakness
• Respiratory failure can occur in late stages of the disease
• Paraneoplastic and autoimmune form of LEMS have similar signs and symptoms

Differential Diagnosis

• Myasthenia Gravis
• Myositis
• Dermatomyositis
• Amyotrophic Lateral Sclerosis
• Limb-Girdle Muscle Dystrophy
• Inclusion Body Myositis

Diagnosis

• Diagnosis is generally a clinical diagnosis
• Confirmation testing for VGCC antibodies
• Neurophysiologic testing

Management

• Guanidine
• Aminopyridines
• Acetylcholinesterase inhibitors
• IVIG
• Glucocorticoids
• Plasma exchange

Disposition

• Referral to rheumatology
• Any patients with risk factors for small cell lung cancer will need to be referred for evaluation of underlying malignancy

References

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