shows evidence of a seizure, but no symptoms are present, it is referred to as a subclinical seizure. Focal seizures Focal seizures often begin with certain experiences, known as an aura. These may include sensory (including visual, auditory, etc.), cognitive, autonomic, olfactory or motor phenomena. In a complex partial seizure a person may appear confused or dazed and cannot respond to questions or direction. Jerking activity may start in a specific muscle group and spread to surrounding muscle groups—known as a Jacksonian march. Unusual activities that are not consciously created may occur. These are known as automatisms and include simple activities like smacking of the lips or more complex activities such as attempts to pick something up. Generalized seizures There are six main types of generalized seizures: tonic-clonic, tonic, clonic, myoclonic, absence, and atonic seizures. They all involve a loss of consciousness and typically happen without warning. Tonic-clonic seizures present with a contraction of the limbs followed by their extension, along with arching of the back for 10–30 seconds. A cry may be heard due to contraction of the chest muscles. The limbs then begin to shake in unison. After the shaking has stopped it may take 10–30 minutes for the person to return to normal. Tonic seizures produce constant contractions of the muscles. The person may turn blue if breathing is impaired. Clonic seizures involve shaking of the limbs in unison. Myoclonic seizures involve spasms of muscles in either a few areas or generalized through the body. Absence seizures can be subtle, with only a slight turn of the head or eye blinking. The person often does not fall over and may return to normal right after the seizure ends, though there may also be a period of post-ictal disorientation. Atonic seizures involve the loss of muscle activity for greater than one second. This typically occurs bilaterally (on both sides of the body). Duration A seizure can last from a few seconds to more than five minutes, at which point it is known as status epilepticus. Most tonic-clonic seizures last less than two or three minutes. Absence seizures are usually around 10 seconds in duration. Postictal After the active portion of a seizure, there is typically a period of confusion called the postictal period, before a normal level of consciousness returns. This period usually lasts 3 to 15 minutes, but may last for hours. Other symptoms during this period