A 58-year-old previously healthy man had complaints of fluctuating drooping eyelids and weakness of neck extensors, arms, and legs. He almost continuously experienced double vision. Following a diagnosis of myasthenia gravis and improvement with pyridostigmine, he noticed twitches and spasms of muscles virtually all over his body. This became severe, he did not sleep well, was restless, and almost continuously felt the urge to move and walk around. His wife mentioned that he also behaved differently. Initially, a pyridostigmine intoxication was considered, but lowering the dose did not help. Additionally, some autonomic features (constipation, erectile dysfunction) appeared.