AbstractBackground. Rasmussen syndrome is a rare, inflammatory and probably autoimmune disease presenting with epilepsia partialis continua which is generally in the form of myoclonic jerks and involves the upper extremities with or without head involvement. We sought to demonstrate the electrophysiological features in patients with Rasmussen syndrome.Methods. We performed continuous electrophysiological recordings of involuntary movement, as well as recordings of startle responses and long latency reflex in three patients with a diagnosis of Rasmussen syndrome.Results. Positive and negative myoclonus were recorded. Startle responses were found to be suppressed. However, long latency reflexes were high in amplitude and one patient even had a C reflex.Conclusion. Stimulus‐sensitive positive and negative cortical myoclonus are typical in epilepsia partialis continua of Rasmussen syndrome and degeneration of brainstem and reticulospinal pathways may develop in Rasmussen syndrome.