What is the role of EEG video monitoring in the diagnosis of 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

EEG video monitoring is the criterion standard for diagnosis and indicated in all patients who have frequent seizures despite taking medications. With an experienced epileptologist, combined electroclinical analysis of both the clinical semiology of the ictus and the ictal EEG findings allows for a definitive diagnosis in nearly all cases. If an episode is recorded, the diagnosis is usually easy, and PNES can usually be differentiated from epilepsy. The principle is to record an episode and demonstrate that no change in the EEG occurs during the clinical event and that the clinical episode is not consistent with seizures unaccompanied by EEG changes. Ictal EEG has limitations because of occasional false-negative results or uninterpretable results if movements generate excessive artifact.

Analysis of the ictal semiology (i.e., video) is at least as important as ictal EEG because it often shows behaviors that are obviously and unquestionably nonorganic and incompatible with epileptic seizures. Certain characteristics of the motor phenomena are strongly associated with PNES: gradual onset or termination; pseudosleep; and discontinuous (stop-and-go), irregular, or asynchronous (out-of-phase) activity (e.g., side-to-side head movement), pelvic thrusting, opisthotonic posturing, stuttering, and weeping. A useful sign is preserved awareness during bilateral motor activity; this is relatively specific for PNES because unresponsiveness is almost always present during bilateral motor activity.

In experienced hands, EEG video monitoring is a highly reliable tool, and in the vast majority of cases, the diagnosis of PNES is not difficult. A small percentage of difficult cases account for the less-than-perfect interrater reliability. [9]

Using video EEG of patients, Hubsch et al. conducted multiple correspondence analysis and hierarchical cluster analysis to construct a practical and useful semiologic classification of PNES, which identified 5 clusters of signs: dystonic attack with primitive gestural activity, pauci-kinetic attack with preserved responsiveness, pseudosyncope, hyperkinetic prolonged attack with hyperventilation and auras, and axial dystonic prolonged attack. [10]

For more information, see the Medscape Reference article EEG Video Monitoring.


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