Initially, these contractions are of a high frequency and low amplitude, which will gradually progress to decreased frequency and high amplitude. An eventual decrease in contraction amplitude just before seizure cessation is also typical.Postictal phaseThe postictal phase causes are multifactorial to include alteration of cerebral blood flow and effects on multiple neurotransmitters. These changes after a generalized tonic–clonic seizure cause a period of postictal sleep with stertorous breathing. Confusion and total amnesia upon regaining consciousness are also usually experienced and slowly wear off as the patient becomes gradually aware that a seizure occurred and remembers their identity and location. Most often, patients regain consciousness within 30 minutes. Rarely, impaired consciousness duration can last several hours after a seizure, especially with a compounding central nervous system condition or a prolonged seizure. Occasionally the patient may vomit or burst into tears from the experienced mental trauma. An additional smaller seizure can also occur several minutes after the main seizure, particularly if the patients seizure threshold has been brought unusually low by known factors or combinations of such. Examples include: severe hangovers, sleep deprivation, elevated estrogen at ovulation, prolonged physical tiredness, and drug use or abuse (including, but not limited to, stimulants, alcohol and caffeine). Rarely, the respiration is inhibited during the postictal phase, leading to sudden unexpected death in epilepsy (SUDEP). Generalized tonic–clonic seizures represent the most important risk factor for SUDEP, especially in patients with nocturnal seizures, who are living alone or do not share a bedroom.
A generalized tonic–clonic seizure, or GTCS, previously known as a Grand mal seizure, is a type of generalized seizure that produces bilateral, convulsive tonic and then clonic muscle contractions. Tonic-clonic seizures are the seizure type most commonly associated with epilepsy and seizures in general and the most common seizure associated with metabolic imbalances. It is a misconception that they are the sole type of seizure, as they are the main seizure type in approximately 10% of those with epilepsy.These seizures typically initiate abruptly with either a focal or generalized onset, the former being known as focal to bilateral tonic-clonic seizure. The seizure itself includes tonic (sustained) and then clonic (repetitive short) contractions. In some seizures, the tonic phase may be preceded by brief, arrhythmic muscle jerks (myoclonus), by a clonic phase or by an absence seizure. After the GTCS, there is an extended postictal state where the person is unresponsive and commonly sleeping with loud snoring. There is usually pronounced confusion upon awakening. Causes
The vast majority of generalized tonic-clonic seizures have a focal origin they start as a smaller seizure that occurs solely on one side of the brain and is referred to as a focal (or partial) seizure. These unilateral seizure types (formerly known as simple partial seizure or a complex partial seizure and now referred to as focal aware seizure and focal impaired awareness seizure, respectively) can then spread to both hemispheres of the brain and cause a generalized tonic-clonic seizure.