What should be the focus of history in the evaluation of suspected psychogenic nonepileptic seizures (PNES)?

Updated: Jul 26, 2018
  • Author: Selim R Benbadis, MD; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Misdiagnosis of epilepsy is common. Misdiagnosis occurs in approximately 25% of patients with a previous diagnosis of epilepsy that does not respond to drugs. Most cases of misdiagnosed epilepsy are eventually shown to be psychogenic nonepileptic seizures (PNES) or, more rarely, syncope. Other paroxysmal conditions are occasionally misdiagnosed as epilepsy, but PNES is by far the most commonly misdiagnosed condition, accounting for >90% of misdiagnoses at epilepsy centers. EEGs misinterpreted as providing evidence for epilepsy often contribute to this misdiagnosis. [3, 4, 5]

Reversing a misdiagnosis of epilepsy can be difficult, as it is with other chronic conditions. Unfortunately, after the diagnosis of seizures is made, it is easily perpetuated without being questioned, which explains the usual diagnostic delay and cost associated with PNES. Despite the ability to diagnose PNES with near certainty by using EEG-video monitoring, the time to diagnosis is long, about 7-10 years. This delay indicates that neurologists may have an insufficiently high enough index of suspicion for PNES.

The patient's history may suggest the diagnosis. Several clues are useful in clinical practice and should raise the suspicion that seizures may be psychogenic rather than epileptic.

Resistance to antiepileptic drugs (AEDs) is usually the first clue and the reason for referral to the epilepsy center, though intractable epilepsy is the other common cause of resistance to AEDs.

Approximately 80% of patients with PNES have been treated with AEDs before the correct diagnosis is made. A psychogenic etiology should be considered when AEDs have no effect whatsoever on the reported frequency of seizures.

The presence of specific triggers that are unusual for epilepsy may suggest PNES, and these triggers should be specifically sought during history taking. For example, emotional triggers such as stress or becoming upset are common in PNES. Other triggers that suggest PNES include pain, certain movements, sounds, and certain types of lights, especially if they are reported to consistently trigger an apparent seizure.

The circumstances in which attacks occur can be helpful. Like other psychogenic symptoms, those of PNES usually occur in the presence of an audience, and an occurrence in the physician's office or waiting room is highly suggestive of PNES. Similarly, PNES usually do not occur during sleep, though they may seem to and though they may be reported as such.

Details of the episodes often include characteristics that are inconsistent with epileptic seizures.


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