Psychogenic non-epileptic seizures
|Psychogenic non-epileptic seizures|
|Classification and external resources|
Psychogenic non-epileptic seizures (PNES), also known as non-epileptic attack disorders (NEAD), are events resembling an epileptic seizure, but without the characteristic electrical discharges associated with epilepsy.
There is no scientific consensus as to what causes PNES. However, many physicians believe the condition may be triggered by psychological problems (irrespective of whether the patient shows any obvious psychological distress or pathology). It is estimated that 20% of seizure patients seen at specialist epilepsy clinics have PNES.
The differential diagnosis of PNES firstly involves ruling out epilepsy as the cause of the seizure episodes, along with other organic causes of non-epileptic seizures, such as syncope, migraine, vertigo, and stroke. However, between 5-20% of patients with PNES also have epilepsy. Frontal lobe seizures can be mistaken for PNES, though these tend to have shorter duration, stereotyped patterns of movements and occurrence during sleep. Next, an exclusion of factitious disorder (a subconscious somatic symptom disorder, where seizures are caused by psychological reasons) and malingering (simulating seizures intentionally for conscious personal gain - such as monetary compensation or avoidance of criminal punishment) is conducted. Finally other psychiatric conditions that may superficially resemble seizures are eliminated, including panic disorder, schizophrenia, and depersonalisation disorder.
The most conclusive test to distinguish epilepsy from PNES is long term video-EEG monitoring, with the aim of capturing one or two episodes on both videotape and EEG simultaneously (some clinicians may use suggestion to attempt to trigger an episode). Conventional EEG may not be particularly helpful because of a high false-positive rate for abnormal findings in the general population, but also of abnormal findings in patients with some of the psychiatric disorders that can mimic PNES. Additional diagnostic criteria are usually considered when diagnosing PNES from long term video-EEG monitoring because frontal lobe epilepsy may be undetectable with surface EEGs.
Following most tonic-clonic or complex partial epileptic seizures, blood levels of serum prolactin rise, which can be detected by laboratory testing if a sample is taken in the right time window. However, due to false positives and variability in results this test is relied upon less frequently.
The use of older terms including pseudoseizures and hysterical seizures are discouraged. While it is correct that a non-epileptic seizure may resemble an epileptic seizure, pseudo can also connote "false, fraudulent, or pretending to be something that it is not." Non-epileptic seizures are not false, fraudulent, or produced under any sort of pretense.
The condition may also be referred to as non-epileptic attack disorder, functional seizures, or psychogenic non-epileptic seizures. Within DSM IV the attacks are classified as a somatoform disorder, whilst in ICD 10 the term dissociative convulsions is used, classed as a conversion disorder.
Some features are more or less likely to suggest PNES but they are not conclusive and should be considered within the broader clinical picture. Features that are common in PNES but rarer in epilepsy include: biting the tip of the tongue, seizures lasting more than 2 minutes (easiest factor to distinguish), seizures having a gradual onset, a fluctuating course of disease severity, the eyes being closed during a seizure, and side to side head movements. Features that are uncommon in PNES include automatisms (automatic complex movements during the seizure), severe tongue biting, biting the inside of the mouth, and incontinence.
If a patient with suspected PNES has an episode during a clinical examination, there are a number of signs that can be elicited to help support or refute the diagnosis of PNES. Compared to patients with epilepsy, patients with PNES will tend to resist having their eyes forced open (if they are closed during the seizure), will stop their hands from hitting their own face if the hand is dropped over the head, and will fixate their eyes in a way suggesting an absence of neurological interference. Mellers et al. warn that such tests are neither conclusive nor impossible for a determined patient with factitious disorder to "pass" through faking convincingly.
Some studies have reported an elevated frequency of childhood abuse in people with PNES. However, others that have controlled for other demographic factors have failed to find a higher rate of reported childhood abuse than in a comparable groups with organic disease (usually epilepsy).
A number of studies have also reported a high incidence of abnormal personality traits or personality disorders in people with PNES such as borderline personality. However, again, when an appropriate control group is used, the incidence of such characteristics it not always higher in PNES than in similar illnesses arising due to organic disease (e.g., epilepsy).
There are a number of recommended steps to explain to people their diagnosis in a sensitive and open manner. A negative diagnosis experience may cause frustration and could cause a person to reject any further attempts at treatment. Ten points recommended to explain the diagnosis to the person and their caregivers are:
- Reasons for concluding they do not have epilepsy
- What they do have (describe dissociation)
- Emphasise they are not suspected of "putting on" the attacks
- They are not 'mad'
- Triggering "stresses" may not be immediately apparent.
- Relevance of aetiological factors in their case
- Maintaining factors
- May improve after correct diagnosis
- Caution that anticonvulsant drug withdrawal should be gradual
- Describe psychological treatment
Psychotherapy is the most frequently used treatment, which might include cognitive behavioral therapy, insight-orientated therapy, and/or group work. There is some tentative evidence supporting selective serotonin reuptake inhibitor antidepressants.
Though there is limited evidence, outcomes appear to be relatively poor with a review of outcome studies finding that two thirds of PNES patients continue to experience episodes and more than half are dependent on social security at three-year followup. This outcome data was obtained in a referral-based academic epilepsy center and loss to follow-up was considerable; the authors point out ways in which this may have biased their outcome data. Outcome was shown to be better in patients with higher IQ, social status, greater educational attainments, younger age of onset and diagnosis, attacks with less dramatic features, and fewer additional somatoform complaints.
Hystero-epilepsy is a historical term that refers to a condition described by 19th-century French neurologist Jean-Martin Charcot where patients with neuroses "acquired" symptoms resembling seizures as a result of being treated on the same ward as patients who genuinely had epilepsy.
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- Epilepsy Foundation article about non-epileptic seizures
- Epilepsy.com article about non-epileptic seizures
- National Society for Epilepsy (UK) article on Non-epileptic attack disorder – a technical article aimed at health professionals