Reversible tongue atrophy in Lambert-Eaton myasthenic syndrome

A 48-year-old man presented with severe limb, bulbar, and respiratory weakness requiring intubation and ventilation. Decrement was seen on repetitive nerve stimulation, but tested muscles were too weak for voluntary activation and tetanic stimulation was not tolerated. Positive voltage-gated calcium channel and SOX1 antibodies confirmed Lambert-Eaton myasthenic syndrome (LEMS). Despite corticosteroids, 3,4-diaminopyridine, and plasma exchange, severe bulbar weakness persisted, the patient remained tracheostomy-dependent, and he developed marked tongue atrophy (figure, A). Small cell lung cancer was subsequently confirmed. Radiotherapy 3 months after presentation resulted in recovery of bulbar function, improvement in tongue atrophy, and tracheostomy decannulation with improvement sustained 10 months later (figure, B and C). Tongue atrophy uncommonly occurs in generalized myasthenia gravis1 but has not been previously reported in LEMS. The underlying mechanism may be neurogenic atrophy due to severe neuromuscular junction dysfunction.2