History
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.
In particular, some characteristics of the motor (i.e., convulsive) phenomena are associated with PNES (see EEG video monitoring in Other Tests). Common and helpful symptoms include side-to-side shaking of the head, bilateral asynchronous movements (e.g., bicycling), weeping, stuttering, and arching of the back. (See video below.) In a study of 120 seizures (36 PNES and 84 epileptic seizures) from 35 patients, only a few signs were reliable in predicting the diagnosis. PNES were predicted by preserved awareness, eye flutter, and episodes affected by bystanders (intensified or alleviated). Epileptic seizures were predicted by abrupt onset, eye-opening/widening, and postictal confusion/sleep. In addition, as compared with signs viewed on video recording, eyewitness reports of these signs were not reliable. [6] It is important to emphasize that no sign isitselfdiagnostic or 100% specific, but fortunately most patients have several of them.
The patient's medical history can be useful. Coexisting, poorly defined, and probably psychogenic conditions, such as fibromyalgia, chronic pain, and chronic fatigue, are associated with psychogenic symptoms. [7] Similarly, a florid review of systems suggests somatization.
A psychosocial history with evidence of maladaptive behaviors or associated psychiatric diagnoses should raise the suspicion of PNES. Pay particular attention during mental status evaluation, especially to the patient's general demeanor, the appropriateness of this or her level of concern, overdramatization, and hysterical features.
Certain symptoms suggest epileptic seizures. These include significant injury. In particular, tongue biting and an ictal cry [8] are highly specific to generalized tonic-clonic seizures and are helpful signs when present.
Antecedent sexual trauma or abuse is thought to be important in the psychopathology of psychogenic seizures and psychogenic symptoms in general. A history of abuse may be more frequent in convulsive rather than limp type of PNES.
Physical Examination
Physical and neurologic findings are usually normal, but the examination can also uncover suggestive features. For example, overly dramatic behaviors, give-way weakness, and a weak voice or stuttering can be useful predictors.
Psychological features suggestive of psychogenic episodes include anxiety, depression, inappropriate affect or lack of concern (la belle indifference), multiple and vague somatic complaints suggestive of somatization disorder, and abnormal interaction with family members.
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Psychogenic nonepileptic attacks. The event is provoked by an induction (or provocative) technique. Note the typical irregular nonclonic nontonic and asynchronous movements (including bicycling) with stop-and-go phenomenon.
