Diagnostic Considerations
The diagnosis of epilepsy refers to recurrent seizures and cannot be made on the basis of a single episode, even if anticonvulsant treatment is administered. This is especially important because of the serious medical, social, economic, and legal consequences surrounding the diagnosis of epilepsy.
The wrong diagnosis of epilepsy is common; 20-30% of cases seen at epilepsy centers are misdiagnosed. [28, 33] The annual cost of misdiagnosis of nonepileptic spells as epileptic seizures has been reported to be between $650 million and $4 billion. [34]
Disease states and conditions often misdiagnosed as epilepsy include the following:
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Convulsive syncope: Decreased cardiac output causes reduced cerebral perfusion with loss of consciousness and convulsive motor activity. Scheepers et al reported that cardiovascular disease was the most common diagnosis among patients whose conditions were initially misdiagnosed as epilepsy. [1] Using a comprehensive battery of cardiovascular tests in a population of patients diagnosed with epilepsy, Zaidi et al reported alternative diagnoses in 41%. [35]
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Transient ischemic attack
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Transient global amnesia
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Paroxysmal vertigo
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Panic attacks
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Migraine
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Sleep disorders, parasomnias, non–rapid-eye movement (REM) parasomnias (eg, night terrors, sleepwalking, and confusional arousals), REM behavior disorder, cataplexy (part of the narcolepsy tetrad, consisting of an abrupt loss of tone), hypnic jerks (ie, benign myoclonic jerks)
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Paroxysmal movement disorders, including acute dystonic reactions, hemifacial spasms, and nonepileptic myoclonus
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Psychogenic nonepileptic attacks: These are the most common conditions at epilepsy monitoring units, comprising more than 90% of misdiagnosed adult cases and more than 50% of cases in children. [33]
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Malingering
Other conditions that may be considered in the evaluation of a new-onset seizure in an adult include the following:
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Chorea gravidarum
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Essential tremor
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Hemifacial spasm
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Hyperammonemia
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Juvenile myoclonic epilepsy
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Restless legs syndrome
Differential Diagnoses
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An electroencephalogram (EEG) recording of a temporal lobe seizure. The ictal EEG pattern is shown in the rectangular areas.
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An electroencephalogram (EEG) recording from a patient with primary generalized epilepsy. A burst of bilateral spike and wave discharge is shown in the rectangular area.
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An electroencephalogram (EEG) recording of a seizure from a subdural array in a patient evaluated for epilepsy surgery. The subdural electrodes record from the left anterior temporal (LAT), left middle temporal (LMT), and left posterior temporal (LPT) regions. The EEG seizure pattern is seen best in bipolar EEG channels LAT 3-4 and LMT 3-4 (rectangular areas).
