Isaacs syndrome is a rare neuromuscular disorder of continuous muscle fibre activity resulting from peripheral nerve hyper excitability. Symptoms commonly include myokymia, pseudomyotonia, muscle cramps and stiffness. It is caused by voltage-gated potassium channel dysfunction and may be inherited or acquired. Recent evidences suggest that autoantibodies against voltage-gated potassium channels (VGKC-Abs) are associated with this disease. Treatment commonly includes anticonvulsants, immunosuppressive therapy and plasma exchange.