Tonic clonic activity (TCA) is a complex phenomenon. It can be a generalized seizure associated with focal epileptiform activity and autonomic phenomena. The onset of TCA has been reported in 3% to 21% of subarachnoid hemorrhage (SAH) patients.In the present study, we investigated the clinical features of the patients with TCA. We also evaluated their physiologic and neuropathologic characteristics. A 19-year-old male patient with no serious medical history presented to the emergency department with seizure-like activity. He denied any infectious symptoms and denied drug use. An EEG was performed.Tonic clonic activity was observed in all extremities. The patient's mother reported unresponsiveness. Emfit Epilepsy Alarm Family witnesses reported an episode lasting 20 minutes with confusion.After an initial period of confusion, a clonic phase appeared with the emergence of slow-wave discharges. A deep cyanosis attack then became shock-like.The patient had a history of epilepsy. Although abnormal laboratory tests and risk factors for seizures were not significantly different between the NCSE group and the NCSE group, ocular movement abnormalities were significantly more common in the NCSE group.Generalized tonic-clonic activity is frequently described as clonic twitching of the face. However, there are many other variations of the pathological rhythms associated with tonic clonic activity.The tonic-clonic phase is usually characterized by a high frequency, low amplitude and slow-wave discharges. During this stage, the person may become sleepy and confused, and he or she might bite the tongue or cheek.The tonic-clonic phase may last for several hours. In some cases, the person will lose bladder control and bowel control.