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Keywords:

  • Lambert–Eaton syndrome;
  • myasthenic syndrome;
  • organ-specific autoimmunity;
  • pernicious anemia;
  • voltage-gated calcium channels

ABSTRACT

Introduction

All descriptions of the Lambert–Eaton syndrome are based on symptomatic patients. We incidentally encountered electromyographic evidence of this syndrome in a patient being studied for another reason. The patient had controlled hypothyroidism and smoked for 9 pack-years but never had symptoms of weakness or had evidence of cancer. Methods: Detailed electrophysiological and serological evaluations were undertaken in this study. Results: Neuromuscular transmission tests were consistent with a presynaptic disorder. Autoantibodies specific for P/Q-type voltage-gated calcium channels (VGCC) were detected in the serum and persisted throughout 7 years of follow-up. Multiple IgG markers of thyrogastric autoimmunity also were detected. Conclusions: This demonstration of asymptomatic Lambert–Eaton syndrome persisting for 8 years provided novel insight into the natural history of the disorder. It is plausible that patients with a subclinical syndrome would have abrupt neuromuscular decompensation when challenged with medications that compromise the safety factor for synaptic transmission. Muscle Nerve 49: 764–767, 2014