A 39-year-old woman presented to the emergency department with a 3-week history of worsening spasms in her axial and lower limb muscles and new-onset urinary retention. Sudden episodes of painful involuntary spasms first appeared in her abdominal muscles 2 weeks after a cold. Soon after, spasms spread to all of her axial muscles and both lower limbs. These paroxysmal episodes lasted a few seconds, occurred up to 20 times a day, and were exacerbated by external stimuli. There was no impairment of consciousness during the attacks. A review of her previous records revealed a diagnosis of Hashimoto thyroiditis 1 month earlier. She had no history of tobacco, alcohol, or drug use.