This is the most common type of generalized seizure and used to be referred to as a “grand mal” seizure. Patients lose consciousness and fall to the ground, after which they have alternating phases of stiffening (tonic) and jerking (clonic).
The tonic phase of a tonic-clonic seizure is described as stiffening of the body for several seconds. During the tonic phase, extraocular movements, apnea, and tongue biting may occur. This phase is also associated with activation of the sympathetic nervous system.
The clonic phase of a tonic-clonic seizure is characterized by rhythmic jerking of the extremities for 30 to 40 seconds. This is because in the clonic phase, muscles spasm and then relax.
Absence seizures, formerly known as “petit mal” seizures, typically occur in children or early adolescents. They are described as brief staring spells or “daydreaming.” This can often go unnoticed and can occur up to 100 times a day if untreated.
A myoclonic seizure is where the patient experiences a sudden, excessive and arrhythmic jerking of the body or extremities. Typically these are brief and occur in clusters, and these jerks are very forceful.
Atonic seizures, or “drop attacks,” involve a sudden loss of muscle tone. The patient falls to the ground, but not before briefly losing consciousness. Patients with atonic seizures have a high risk of head injury and can be seen wearing protective helmets.
Partial seizures are also known as focal seizures and begin in one hemisphere of the brain, or in a specific region of the cortex. Thus, the seizures show symptoms specific to the affected part of the brain. There are simple and complex partial seizures, describing if consciousness is maintained or lost.
In a simple partial seizure, the person maintains consciousness, but experiences unusual feelings or sensations. This includes emotional feelings, tastes, sounds, visual phenomena, and physical sensations.
In complex partial/focal seizures, patients have a loss or impairment in consciousness. They can experience a daydream-like feeling or develop temporarily strange behaviors called automatisms (unconscious repetitive movements).
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