If the clinician observes one or more NESs, the phenomenology of the event may raise suspicion that the patient does not have epilepsy. Nothing in the clinical expression of NESs can be considered definitively pathognomonic, however. Only by recording the behavioral and electrographic characteristics can the event be diagnosed confidently.

One common clue is that NESs often have a gradual onset, but epileptic seizures typically start and end suddenly. For example, a simple absence seizure (formerly known as petit mal) begins with sudden loss of awareness, which continues for several seconds and then ends abruptly, at which time the person is fully aware and functional. Similarly, a tonic-clonic epileptic seizure begins suddenly with a fall, loss of consciousness, and frequently a cry. Motor activity continues for a minute or so, progressing predictably and ending abruptly. At that point the patient is deeply comatose and flaccid. With NESs, on the other hand, consciousness may be preserved during the peri-ictal phase.

In contrast, a nonepileptic seizure characterized by vigorous motor activity frequently builds in intensity as the event progresses. The event itself is often of longer duration than its epileptic counterpart, sometimes lasting many minutes or even hours. Moreover, the motor movements may have a waxing and waning quality through the course of the seizure. (Some NESs with motor manifestations are characterized by vigorous motor activity and intervening periods of quiet unresponsiveness.) The event tends to subside gradually, and the postictal state-whether unresponsiveness or apparent confusion-is less profound than in the case of a tonic-clonic convulsion.

Although it is often said that tongue biting and incontinence do not occur with NESs, some patients with documented NESs have reported these symptoms. Bladder and bowel incontinence and self-injury are rare but can occur. When biting occurs, it tends to involve the tongue tip, arms, or other body areas more than the sides of the tongue.

NESs that resemble true absence attacks are more difficult to differentiate from epilepsy than motor events. The staring, unresponsive state provides no obvious clues concerning the nature of the attack. However, if such attacks are of long duration, one might suspect that the diagnosis is other than epilepsy. The only way to confirm the true diagnosis is to record the event in question by EEG monitoring, preferably with simultaneous video monitoring.

Patients with NESs resembling complex partial seizures also present diagnostic difficulties, owing to the protean manifestations of the epileptic events. Such patients may exhibit confusional states with or without apparent automatic activities. Again, recording of the event is essential to confirm the diagnosis.

Another feature suggestive of NESs is an emotional response during or after an event. Crying and other emotional vocalizations are common. Although crying occurs in rare patients with epilepsy, it is more frequent in those with NES.

Typical NESs, especially motor events, do not seem to follow a "physiologic" progression. The motor activity tends to be chaotic, sometimes with flinging movements. Alternation of the movements, opisthotonus, pelvic thrusting, and dystonic posturing may be present. One important distinguishing feature of NESs is that, in contrast to epileptic seizures, the face is often not involved.

Some patients with NES exhibit avoidance behavior during events, especially during quiescent phases. For example, if the patient's arm is held aloft and released, the patient may avoid striking himself or herself in the face. Such behavior suggests that the attack is nonepileptic.

In some cases NESs can be initiated and ended by suggestion and verbal intervention.

What is the diagnostic role of prolactin levels?

Elevations in serum prolactin occur in the postictal phase (20 to 25 minutes after the seizure subsides) after some types of epileptic seizures. The most consistent increase is found after generalized tonic-clonic convulsions.

NESs do not usually raise prolactin levels, although this observation has been disputed. Thus, prolactin levels can be useful in some cases of NES, but they cannot be considered diagnostic. (See more about postictal prolactin testing.)

What epileptic seizures are most likely to be mistaken for NESs?

Frontal lobe seizures

Seizures originating in the frontal lobe, including the supplementary motor area, present a major diagnostic dilemma in differentiating NES from epilepsy. Frontal lobe seizures may be characterized by prominent, chaotic, apparently "nonphysiologic" motor activity, such as flailing, alternating repetitive movements of the extremities, "bicycling" movements of the lower extremities, and tonic posturing. To most observers, such a picture appears to be clearly psychogenic or "hysterical." Moreover, the patient retains a degree of awareness during this stage. After the event subsides, there is little or no confusion. These factors appear to confirm that the event was not epileptic.

Frontal seizures often include a brief phase of tonic posturing that precedes the chaotic motor phase. This phase may take the form of abduction of the upper extremities or unilateral posturing with deviation of head and eyes. Forced downward deviation of the eyes has been observed. There may be accompanying vocalization. During this phase the patient is unresponsive, and the transition to the chaotic motor phase is rapid and abrupt. Inasmuch as the initial phase is frequently unobserved whereas the prominent motor activity commands attention, the suspicion that the event may be epileptic is correspondingly diminished.

Seizures with pelvic thrusting movements

Pelvic thrusting movements are often regarded as a sign of NESs, but such movements can be seen in epileptic seizures, either during tonic-clonic convulsions or with complex partial seizures. Pelvic movements in tonic-clonic convulsions are more likely to be retropulsive, however, whereas those associated with NESs are usually propulsive.

Seizures with gradual onset and cessation

The features of gradual onset and gradual cessation, suggestive of NESs, may be present in varying degrees in generalized convulsions or complex partial seizures. The "gradual" aspect of epileptic seizures is more apparent than real; the electrographic seizure begins abruptly, but the clinical expression may seem gradual.

Prolonged or intermittent seizures

The duration of generalized tonic-clonic convulsions and complex partial seizures is usually under 2 minutes, but either seizure type may be prolonged. In addition, the seizures may appear to be intermittent, such as in complex partial status epilepticus or in serial motor seizures.

Clues from the response to treatment

NESs and epilepsy frequently coexist in the same patient. The best available data suggest that in 20% of NES cases there is either a past history of epilepsy or coexisting epileptic seizures (Ramsay 1993).

The presence of both conditions complicates both diagnosis and management. Because the physician usually does not observe the event and it is difficult for most people to describe sudden or rapidly evolving events, a presumptive diagnosis of epilepsy is likely. Changes in therapy probably will be based on a seizure record that contains both epileptic seizures and NESs. Increases in the dosage of antiepileptic drugs (AEDs) will follow reports of continuing seizures, even though the true problem may be superimposed NESs.

If AED dosage increases do not alter the seizure frequency or if seizures appear to increase with increased doses, the possibility of NESs or coexisting epilepsy and NESs should be considered.

Tapering AEDs, on the other hand, may exacerbate epileptic seizures but should not change the frequency of NESs.

Adapted from: Rowan AJ. Diagnosis and management of nonepileptic seizures. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 173-184. With permission from Elsevier (www.elsevier.com).

Authored By: 
Orrin Devinsky
Authored Date: