If the entire cerebral cortex is involved in the seizure from the onset of the seizure, the seizure is classified as primary generalized. The following are types of primary generalized seizures:
• Tonic-clonic: Characterized by a sudden loss of consciousness accompanied by tonic extension and rhythmic clonic contractions of all major muscle groups. The duration of the seizure is usually 1 to 3 minutes. These seizures are often described as "grand mal."
• Absence: Characterized by sudden and brief (i.e., several seconds in duration) losses of consciousness without muscle movements. These seizures are often described as daydreaming or blanking out episodes. A common term for these seizures is "petit mal."
• Myoclonic: Characterized by single and very brief jerks of all major muscle groups. Patients with these seizures may not lose consciousness due to the seizure lasting less than 3 to 4 seconds. Patients may describe these seizures as shoulder shrugs or spinal chills. Myoclonic seizures may cluster and build into a generalized tonic-clonic seizure.
I. Localization-related (focal, local, partial) epilepsies and epileptic syndromes
A. Idiopathic with age-related onset
1. Benign childhood epilepsy with centrotemporal spikes
2. Childhood epilepsy with occipital paroxysms
II. Generalized epilepsies and epileptic syndromes A. Idiopathic and age-related onset
1. Benign neonatal epilepsy
2. Childhood absence epilepsy (pyknolepsy)
3. Juvenile myoclonic epilepsy (impulsive petit mal)
4. Juvenile absence epilepsy with generalized tonic-clonic seizure on awakening
B. Secondary (idiopathic or symptomatic)
1. West's syndrome (infantile spasms)
2. Lennox-Gastaut syndrome
1. Nonspecific etiology (early myoclonic encephalopathy)
2. Specific syndromes (epileptic seizures that may complicate many diseases, e.g., Ramsay-Hunt syndrome, Unverricht's disease)
• Atonic: Characterized by loss of consciousness and muscle tone. No muscle movements are typically noted, and the patient falls if not lying down or sitting in a chair. These seizures may be described as "falling out."
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