A tonic-clonic seizure is a common, potentially severe type of generalized seizure that involves forceful muscle contractions and loss of consciousness and memory. Most tonic-clonic seizures last for about one to three minutes, though it is possible for an attack to last up to 30 minutes or for several seizures to occur in a short period of time. The first signs of a tonic-clonic seizure are typically a shrill cry followed by a collapse to the ground. Within a few seconds, a sufferer starts to convulse violently and uncontrollably. An individual who witnesses another person having a seizure should contact emergency medical services immediately.
The exact symptoms of a tonic-clonic seizure can be different for different people. For many, a phenomenon called an aura precedes an attack. An aura can be a strange tingling feeling, an odd smell or taste, or a visual hallucination. Aura symptoms typically arise a few minutes or seconds before a seizure, and there is usually no way to stop the impending attack.
The first stage of the actual seizure, the tonic stage, involves a sudden loss of consciousness and a tightening of most or all of the muscles in the body. Many sufferers let out screams just as their seizures set in because their vocal cord muscles forcefully contract. Stiff leg muscles cause people to fall down, and contractions in the throat and mouth can lead to bitten tongues and shallow or absent breathing. The skin and lips also may appear blue due to a lack of oxygen.
The tonic stage typically lasts about 15 seconds, followed by the clonic stage. Muscles begin to unpredictably relax and contract, causing the limbs and neck to jerk in a violent, rhythmic pattern. Bowel and bladder incontinence are common during a tonic-clonic seizure. After a few minutes, jerking stops and consciousness slowly begins to return. The sufferer usually feels very weak, confused, and sleepy for several hours. Massive headaches can occur after a tonic-clonic seizure as well.
It is important to call for help and provide assistance for a person who is having a tonic-clonic seizure. Trying to grab and restrain the sufferer during the attack can be dangerous, so a bystander should instead try to remove nearby objects such as chairs and tables to help avoid injury to jerking limbs. Once violent movements stop, the sufferer should be moved onto his or her side to promote better breathing. Emergency responders can assess the situation when they arrive and provide additional first aid if necessary.