Generalized Tonic Clonic Seizures

Clinic

• GTCS, previously known as a grand mal seizure, is a type of generalized seizure that produces bilateral, convulsive tonic and then clonic muscle contractions
• Prevalance:10% of epilepsies.

• It 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 smaller unilateral seizure types were formerly known as simple partial seizure or a complex partial seizure, and are now referred to as focal aware seizure and focal impaired awareness seizure, respectively. Unilateral seizures can then spread to both hemispheres of the brain and cause a generalized tonic-clonic seizure. This type of seizure has a specific term called "focal to bilateral tonic-clonic seizure."

Other generalized tonic-clonic seizures are idiopathic, start in large networks involving both hemispheres, and have a presumed genetic cause. Precipitating factors include chemical and neurotransmitter imbalances and a genetically or situationally determined seizure threshold, both of which have been implicated. The seizure threshold can be altered by fatigue, malnutrition, lack of sleep or rest, hypertension, stress, diabetes, the presence of strobe-flashes or simple light/dark patterns, raised estrogen levels at ovulation, fluorescent lighting, rapid motion or flight, blood sugar imbalances, anxiety, antihistamines and other factors. Tonic–clonic seizures can also be induced deliberately with electroconvulsive therapy.

In the case of symptomatic focal epilepsy, the cause is often determined by MRI or other neuroimaging techniques showing that there is some degree of damage to a large number of neurons. The lesions (i.e., scar tissue) caused by the loss of these neurons can result in groups of neurons forming a seizure "focus" area with episodic abnormal firing that can cause seizures if the focus is not abolished or suppressed via anticonvulsant drugs.

Sign / Symptoms

• Prodrome: Most generalized tonic–clonic seizures begin without warning and abruptly, but some epileptic patients describe an Aura, which is a sort of premonitory feeling hours before a seizure.
• This type of prodrome is distinct from stereotypic aura of focal seizures that become generalized seizures.
• Tonic–clonic seizure comprises three phases:
  1. Tonic phase is usually the first phase. Consciousness will quickly be lost and the skeletal muscles will suddenly tense, often causing the extremities to be pulled towards the body or rigidly pushed away from it, which will cause the patient to fall if standing or sitting. There may also be upward deviation of the eyes with the mouth open. The tonic phase is usually the shortest part of the seizure, normally lasting only 10–20 seconds. The patient typically expresses brief vocalizations like a loud moan upon entering the tonic stage, due to air being forcefully expelled from the lungs. This vocalization is commonly referred to as an "ictal cry". Starting in the tonic phase, there may also be bluing of the skin from respiration impairment and pooling of saliva in the back of the throat. Increased blood pressure, pupillary size and heart rate (sympathetic response) may also be noted with clenching of the jaw possibly resulting in biting the tongue. The initial tonic phase may be preceded by repetitive rhythmic or arrhythmic jerks or by the absence seizure.
  2. Clonic phase is an evolution of the tonic phase and is caused by muscle relaxations superimposed on the tonic phase muscle contractions. This phase is longer than the tonic phase with the total ictal period usually lasting no longer than 1 minute. Skeletal muscles will start to contract and relax rapidly, causing convulsions. These may range from exaggerated twitches of the limbs to violent shaking or vibrating of the stiffened extremities. The patient may roll and stretch as the seizure spreads. 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.
  3. 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.

Entity / Miasm

	JE	TBE	PLV	RBS	VZV	HSV-1	HSV-2	RBL	EEE/WEE	CXA/B/ECHO	RBOL	INFL
Aphasia	+++	+++	+++		+++
Retinitis					+++	+++	+++	+++
Visual field deficit / Blindness	+++				+++	+++	+++	+++	+++	+++
Parestesia		+++	+++	+++	+++	+++	+++			+++		+++
Fear		+++	+++	+++	+++
Olfactory halucination		+++
Thermoregulatory disturbances											+++
Hemiparesis	+++	+++
Halucination	+++	+++	+++	+++	+++	+++	+++		+++
Post ictal Amnesia		+++