Lambert-Eaton myasthenic syndrome: Difference between revisions

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==Clinical Features==
==Clinical Features==
*Often presents with alteration in gait or difficulty rising from a chair
*Fluctuating symmetric weakness and fatigue, esp of proximal leg muscles
*Fluctuating symmetric weakness and fatigue, esp of proximal leg muscles
*Improvement in strength with sustained or repeated exercise (in contrast to MG)
*Improvement in strength with sustained or repeated exercise (in contrast to MG)
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*Paresthesias
*Paresthesias
*Metallic taste
*Metallic taste
*Autonomic symptoms (dry mouth, impotence)
*Eye movements are unaffected
*Eye movements are unaffected
*Sensory examination normal
*Sensory examination normal
*Often presents with alteration in gait or difficulty rising from a chair
*Symmetrical muscle weakness and fatiguability often beginning in lower extremities
*Symmetrical muscle weakness and fatiguability often beginning in lower extremities
*Autonomic dysfunction (dry mouth, erectile dysfunction)
*Autonomic dysfunction (dry mouth, erectile dysfunction)
*Compared with myastenia gravis, ELS begins with lower extremities weakness and rarely begins with extraocular muscle weakness
*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
*Respiratory failure can occur in late stages of the disease
*Paraneoplastic and autoimmune form of LEMS have similar signs and symptoms  
*Paraneoplastic and autoimmune form of LEMS have similar signs and symptoms


==Differential Diagnosis==
==Differential Diagnosis==

Revision as of 12:59, 7 February 2016

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

Epidemiology

  • Predominantly a disease associated with older men with 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

  • Often presents with alteration in gait or difficulty rising from a chair
  • 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
  • Eye movements are unaffected
  • Sensory examination normal
  • 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

Weakness

Diagnosis

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

Treatment

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


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

Disposition

  • Admission required when infectious complications occur or when severe disability requires inpatient immunotherapy
  • Referral to rheumatology
  • Any patients with risk factors for small cell lung cancer will need to be referred for evaluation of underlying malignancy

See Also

References