We describe a patient who presented with fatigue and pulling sensation in his lower limbs. He had continuous muscle contractions over his trunk (myokymia) which pointed towards the diagnosis of Isaacs syndrome which was confirmed by strongly positive CASPR2 antibodies in blood.

A 40-year-old man presented with history of fatigue, low back ache, and dragging sensation in both his lower limbs since 1 month. On examination, there was continuous undulatory twitching of muscles (myokymia) over his right upper back (Video S1). He had normal muscle power and brisk deep tendon reflexes. MRI spine did not show any significant abnormality except early cervical spondylotic changes. He was clinically suspected to have Isaacs syndrome. CASPR2 antibodies in blood were strongly positive and confirmed the diagnosis. 1 Workup for systemic autoimmune diseases and malignancies was unremarkable. He was given pulse of high dose intravenous methylprednisolone 1 g for 5 days and oral phenytoin at a dose of 5 mg/kg daily. His symptoms were significantly reduced, and myokymia disappeared on follow-up after 1 month. AUTHOR CONTRIBUTIONSAlex Rebello conceptualized, organized, and executed the study, prepared the manuscript, collected the data, and involved in review. Mohd. Asif, Bandi Haritha, Nangadda Narmada, and Kumbha Dhanusha prepared the manuscript and collected the data. Ram Chandra Poudel executed the study, and involved in review and critique. ACKNOWLEDGMENTWe acknowledge the constant support and motivation of Amith Kumar S, who also suggested the title of the article. CONFLICT OF INTERESTNone. DATA AVAILABILITY STATEMENTThe data that support the findings of this study are available from the corresponding author upon reasonable request. CONSENTWritten informed consent was obtained from the patient to publish this report in accordance with the journal's patient consent policy.