Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 8 5 2024 04 20 217 222 Rasa Zafari School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mona Ahmadi Neurosciences Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran 2023 09 24 2023 11 22 Isaacs Syndrome (IS) is an autoimmune disease characterized by fasciculations, dysautonomia, and hyperactivity of muscle fibers due to hyperexcitability of the peripheral nerve system. Patients with IS often express voltage-gated potassium channels (VGKCs), contactin-associated protein 2 (CASPR2), and leucine-rich glioma- inactivated protein (LGI1) antibodies. Slower rates of grouped fasciculation, known as myokymia, are a common presentation in IS patients. Recently, carbamazepine has been considered as the first-line treatment to alleviate the symptoms of IS patients. In this report, the authors present a case of a female patient with ramps and unintended movements in the abdomen and both lower limbs. She was diagnosed with IS after the detection of myokymia in the needle electromyography (EMG) and a positive paraneoplastic panel for CASPR2 and LGI antibodies. The patient is now symptom-free due to the administration of Carbamazepine, Gabapentin, and Baclofen. Additionally, due to her potential risk for solid tumors, she is under regular follow-up. https://crcp.tums.ac.ir/index.php/crcp/article/view/872