With her consent, the psychiatrist obtained collateral information from her brother. He reported that his sister had received a diagnosis of “pseudoseizures” about 5 years before this presentation. The brother was unsure of any emotional precipitants.
Table 1
Psychiatric disorders that may precipitate or coexist with PNES
| Psychopathology | Differentiation |
|---|---|
| Somatoform disorders | Physical symptoms suggest a medical condition but are not the result of a medical condition, substance, or another mental disorder such as panic disorder or schizophrenia |
| Conversion disorder | Psychological symptoms expressed as neurologic symptoms—such as paralysis, blindness, or paresthesia—in the absence of a known medical or neurologic disorder |
| Dissociative disorder | Disruption in consciousness, memory, identity, or perception that may be sudden or gradual, transient or chronic |
| Depressive disorders | Mood or anxiety symptoms related to depressive, bipolar, panic, posttraumatic stress, or acute stress disorders may coexist with PNES |
| Psychotic disorders | Schizophrenia may be associated with seizure-like events in some patients12 |
| Factitious disorder | Seizure-like symptoms may be produced intentionally for secondary gain (as in malingering) or feigned to assume a sick role (as in factitious disorder) |
| Developmental disorders | In a patient with mental retardation, PNES may result from reinforced operant behavior patterns |
| Source: Diagnostic and statistical manual of mental disorders (4th ed., text rev).11 | |
PNES OR EPILEPSY?
Initial assessment of suspected PNES includes a medical, psychiatric, social, psychological, and substance abuse history, as well as a thorough physical examination.
In patients with suspected PNES, obtain collateral histories of seizure precipitants, abortants, childhood events, and family history. Ms. X, for example, has a history of depression and at least one past episode of probable PNES, as described by her brother. An argument with her husband apparently precipitated the most recent seizure episode.
Table 2
Psychogenic seizures PNES vs. epileptic seizures: Differences in presentation*
| Clinical features | Psychogenic nonepileptic seizures (PNES) | Epileptic seizures |
|---|---|---|
| Duration | Variable | Short (20 to 70 seconds) |
| Pattern | Variable | Stereotyped |
| Frequency | Variable | Paroxysmal, cluster |
| Cause | Emotional | Organic |
| Occurs in presence of others | Yes | Variable |
| Occurs during sleep | Rare | Yes |
| Incontinence | Rare | Frequent |
| Biting pattern | Tip of tongue, lips | Side of tongue, cheek |
| Convulsion | Bizarre, trashing, sexual movements | Tonic-clonic |
| Injury | Infrequent, mild | Infrequent, severe |
| Pupillary reflex | Normal | Slow, nonreactive |
| Babinski’s reflex | No | Yes, if convulsion |
| Orientation afterwards | Clear | Confused |
| Postictal stupor | Rare | Frequent |
| Serum prolactin | Normal | Elevated (>18 ng/mL in men; >30 ng/mL in nonpregnant women) |
| EEG | Normal | Abnormal or variable |
| * Apply loosely, as the spectrum of seizure types within epilepsy is very large. | ||
| Source: Adapted from reference 13. | ||
PNES features. Clinical features (Table 2)13—although not definitive—can help differentiate PNES from epileptic seizure.1 PNES features to look for include:
- prolonged and bizarre prodrome
- prominent out-of-phase ictal or postictal activity
- clear-cut precipitants, especially in an emotionally charged atmosphere
- lack of falls or injuries
- fluctuating consciousness or vivid recall of details during ictal moments.
PNES’ physical symptoms are not voluntary. Patients often have out-of-phase upper- and lower-extremity movements and vocalization as the event starts, as opposed to about 20 seconds into the event when true tonic-clonic seizure makes the tonic-clonic transformation. Other common features are high-amplitude, forward pelvic thrusting, and lack of rigidity. Weeping during an apparent seizure strongly suggests a nonepileptic event.14
Ictal duration can be useful in assessment. Events that resemble tonic-clonic seizure but continue for >70 seconds or <20 seconds raise suspicion of nonepileptic seizures, although status epilepticus is possible.
Prolactin elevation. Epileptic tonic-clonic and partial complex seizures increase serum prolactin and are most reliable approximately 20 minutes after event onset. Nipple manipulation can spuriously increase serum prolactin, so observe female patients for this behavior if a seizure occurs in your presence. Psychotropics such as chlorpromazine and haloperidol may also elevate serum prolactin.
INVESTIGATIONS
Video EEG recording is available in most neurologic centers and is the investigation of choice. Epileptic seizure is characterized by recruitment of seizure activity in a physiologic distribution and postictal slowing, which would be difficult for a patient to imitate.
Unlike traditional EEG, video EEG shows evidence of electrographic paroxysmal changes immediately before, during, or after an epileptic seizure.15 Seizure presentations without paroxysmal electrographic changes would be considered PNES.
Traditional EEG is not recommended for a PNES workup because seizure activity is not recorded and myogenic infarcts may obscure readings. Moreover, because interictal EEG changes may occur even in patients with PNES, these changes in isolation cannot be interpreted as evidence of epilepsy.16
Laboratory testing includes full blood count, electrolytes, urea and creatinine, urine drug screen, and thyroid and liver function tests, as well as serum levels in patients taking anticonvulsants. These tests may exclude some seizure causes (such as hypokalemia or hypocalcemia with electrolyte disturbances) and provide baseline values for monitoring drug toxicity. Thyroid function testing will rule out hypo- or hyperthyroidism in patients with comorbid depressive or anxiety disorders. Urine drug screen reveals evidence of drug abuse—a possible organic seizure disorder precipitant.
Normal serum prolactin (men: 2 to 18 ng/mL; nonpregnant women: 3 to 30 ng/mL), cortisol (5 to 22 mcg/dL, morning blood specimen), and creatine kinase (50 to 200 U/L) rise substantially after an epileptic—but not psychogenic—seizure.17 Note, however, that creatine kinase and prolactin may be as elevated in PNES as in an epileptic seizure if PNES presents with vigorous muscular activity.18