Diagnostic Considerations
Not seizures
Generally, the differential diagnosis of seizures include syncope, psychogenic nonepileptic attacks, migraine, transient ischemic attack (TIA), gastrointestinal reflux resulting in Sandifer syndrome, REM behavior disorder, narcolepsy, cataplexy, parasomnia, tics, nonepileptic myoclonus, tremors, transient global ischemia, and panic.
In patients who are neurologically impaired (mental retardation or cerebral palsy), nonepileptic seizurelike behaviors can also be misinterpreted as seizures. These types of conditions include paroxysmal movement disorders (tonic spasms) associated with cerebral palsy, mannerisms, and self-stimulating repetitive behaviors, as well as nonepileptic staring spells.
Video-EEG is essential in ensuring that events are properly classified. Go to EEG in Common Epilepsy Syndromes and Generalized Epilepsies on EEG for more information.
Other types of epilepsy
Symptomatic generalized epilepsy (SGE) is different from idiopathic (primary) generalized epilepsy, which, by definition, has a genetic etiology and is not associated with evidence of brain dysfunction other than the seizures. Idiopathic (primary) generalized epilepsy (eg, childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy) is usually not difficult to differentiate because these patients are neurologically and intellectually normal, they do not have tonic or atonic seizures, and because EEG findings are normal other than the epileptiform abnormalities.
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Atonic seizure. Abrupt loss of muscle tone is followed by clonic rhythmic movements. This type of seizure is typical for the symptomatic generalized epilepsies of the Lennox-Gastaut type.
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Electroencephalogram demonstrating hypsarrhythmia in infantile spasms. Note the chaotic high-amplitude background.
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Electroencephalogram demonstrating hypsarrhythmia. Note the electrodecremental response that is associated with a spasm in infantile spasms (ie, West syndrome).
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Slow (< 2.5 Hz) electroencephalographic spike and wave discharges associated with atypical absence seizures (ie, Lennox-Gastaut syndrome).
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Slow (< 2.5 Hz) electroencephalographic spike and wave discharges in atypical absence epilepsy (ie, Lennox-Gastaut syndrome).
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Spike, generalized. Significant spikes usually are followed by a slow wave, as shown here. This example also illustrates that generalized spikes are typically maximal frontally. This is typical of primary (ie, idiopathic, genetic) epilepsies. If burst lasted 3 seconds or more, it could be classified as spike-wave complexes.
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Slow spike-wave complexes. In addition to being slower, they are also less monomorphic than 3-Hz spike-wave complexes. With other findings, this often is seen in symptomatic/cryptogenic epilepsies of Lennox-Gastaut type.
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Slow spike-wave complexes. In addition to being slower, they are also less monomorphic than 3-Hz spike-wave complexes. With other findings, this often is seen in symptomatic/cryptogenic epilepsies of Lennox-Gastaut type.
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Hypsarrhythmia. High-amplitude slowing with no organized background and multifocal spikes (left and right frontal in this sample). This is phenotype of first year of life and is associated with West syndrome (ie, infantile spasms).
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Hypsarrhythmia. High-amplitude slowing (note scale) with no organized background and multifocal spikes (right frontal and left occipital in this sample). This is phenotype of first year of life and is associated with West syndrome (ie, infantile spasms).
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Generalized paroxysmal fast activity and electrodecrement. This pattern is characteristic of symptomatic/cryptogenic epilepsies of Lennox-Gastaut type and may be subclinical or associated with tonic or atonic seizures.
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Typical generalized tonic seizure in an adult patient with a "symptomatic" (now termed structural-metabolic) generalized epilepsy of the Lennox-Gastaut type.
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Typical generalized tonic seizure in a patient with a "symptomatic" (now termed structural-metabolic) generalized epilepsy of the Lennox-Gastaut type and severe static encephalopathy with cerebral palsy.
