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A seizure is an episode of abnormal neurologic function caused by an inappropriate electrical discharge of brain neurons. The seizure is the clinical attack experienced by the patient. Some patients with “epileptic” electroencephalographic (EEG) discharges may not experience any overt clinical symptoms. Some seizure-like clinical episodes may be due to causes other than abnormal brain electrical activity, but such attacks, however impressive, are not true seizures.

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Epilepsy is a clinical condition in which an individual is subject to recurrent seizures. It implies a more or less fixed condition of the brain responsible for the seizures. The term epileptic does not refer to an individual with recurrent seizures caused by reversible conditions such as alcohol withdrawal, poisoning, hypoglycemia, or other metabolic derangements.

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Primary or idiopathic seizures are those in which no evident cause can be identified. Secondary or symptomatic seizures are a consequence of an identifiable neurologic condition, such as a mass lesion, previous head injury, or stroke. Electrical stimulation of the brain, convulsant potentiating drugs, profound metabolic disturbances, or a sharp blow to the head may cause reactive seizures in otherwise normal individuals. Reactive seizures are generally self-limited, and a reactive seizure is not considered to be a seizure disorder or epilepsy.

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The International League Against Epilepsy1 recommends dividing seizures into two major groups: generalized seizures and partial seizures (Table 165-1). When there is inadequate data to categorize the seizure, the seizure is considered unclassified.

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Table Graphic Jump Location
Table 165-1 Classification of Seizures 
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Generalized Seizures

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Generalized seizures are thought to be caused by a nearly simultaneous activation of the entire cerebral cortex, perhaps caused by an electrical discharge originating deep in the brain and spreading outward. The attacks begin with abrupt loss of consciousness. Loss of consciousness may be the only clinical manifestation (as in absence attacks) of the seizure, or there may be a variety of motor manifestations (myoclonic jerks, tonic posturing, clonic jerking of the body and extremities, etc.).

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Generalized tonic-clonic seizures (grand mal) are the most familiar and dramatic of the generalized seizures. They begin with abrupt loss of consciousness without warning or aura. In a typical attack, the patient suddenly becomes rigid, trunk and extremities are extended, and the patient falls to the ground. Patients are often apneic during this period and may be deeply cyanotic. They often urinate and may vomit. As the rigid (tonic) phase subsides, there is increasing coarse trembling that evolves into a symmetric, rhythmic (clonic) jerking of the trunk and extremities. As the attack ends, the ...

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