Neuromyotonia is a nervous system disorder characterized by muscle stiffness and continuous muscle twitching. This condition can also be called Isaacs' syndrome after the physician who first described it. However, there are many other synonyms for neuromyotonia, including neuromyotonic disorder, peripheral nerve hyperexcitability, cramp-fasciculation syndrome, and Isaac-Merten syndrome. Additionally, other related conditions may be mistaken for neuromyotonia, such as stiff-person syndrome or myoclonus. Knowing the different synonyms and related conditions can help clinicians and patients more accurately identify this rare disorder and tailor appropriate treatments.