Lambert-Eaton myasthenic syndrome as a cause of persistent neuromuscular weakness after a mediastinoscopic biopsy -A case report-

Abstract

There are many causes of prolonged postoperative muscle weakness, including drugs, residual anesthetics, cerebrovascular events, electrolyte imbalance, hypothermia, and neuromuscular disease. Neuromuscular diseases are relatively rare, with the most common being myasthenia gravis and Lambert-Eaton myasthenic syndrome (LEMS). We report an unusual case in which a patient who was given a muscle relaxant during mediastinoscopy developed postoperative muscle weakness that was ultimately diagnosed as secondary to LEMS.

Keywords: Lambert-Eaton myasthenic syndrome; Neuromuscular disease; Postoperative muscular weakness.

Fig. 1

Repetitive stimulation of the ulnar nerve at low and higher rates. Trial 2 is single post-exercise stimulation that shows a marked incremental response compared with a single stimulation (trial 1). Repetitive stimulation of the ulnar nerve at low rates (Trials 3 to 5 at 2, 3, and 5 Hz, respectively) produced a decremental response in the amplitude of the compound muscle action potentials (CMAPs) recorded from the left abductor digiti minimi muscle. By contrast, stimulation at higher rates (Trial 6; 50 Hz) definitely produced an incremental response in the amplitude of the CMAP.