Information about non-epileptic seizures (NES)
for health professionals
NEST Group 2009
NEST GROUP
The Non-Epileptic Seizure Treatment (NEST) group was formed in 2005 as interdisciplinary collaboration of clinicians and academics working in Sheffield, Leeds and Manchester. The aim of the group is to develop and evaluate new treatments for non-epileptic seizures (NES).
The group includes professionals from the fields of neurology, psychiatry, clinical psychology and psychotherapy.
Contents
NEST 1
Some General Remarks about NES 4
Definition 5
Epidemiology 5
Diagnosis 6
Predisposing, Precipitating and Maintaining Factors 7
Treatment 11
Outcome 11
Model of NES 12
Further Reading 13
Some general remarks about NES
Many different names are used for non-epileptic seizures (NES). Terms such as psychogenic, dissociative, conversion, functional and hysterical seizures, pseudoseizures, non-epileptic attacks, non-epileptic events or medically unexplained transient loss of consciousness (TLOC) describe the same problem. None of these labels is perfect. Most can be misunderstood and some are likely to offend patients. The term “pseudoseizure” seems to question the true nature of the events. The expressions “dissociative” and “conversion” seizures imply a particular aetiology and a relationship with trauma or distress which may not be relevant in all patients.
One reason why it is difficult to find a good name for NES is the fact that NES can occur in many different clinical scenarios. NES can be the core symptom of a disorder or a relatively insignificant aspect of a more complex problem – such as in patients with many different medically unexplained symptoms or patients with medically explained conditions (for instance epilepsy) who also have occasional NES. NES can occur in the context of time-limited adjustment problems or be the key manifestation of a chronically disabling seizure disorder. In other words, there are many different NES disorders.
Definition
Non-epileptic seizures (NES) are episodes of impairment of self-control associated with a range of motor, sensory and cognitive symptoms, which superficially resemble epileptic seizures but are not associated with abnormal electrical activity in the brain. NES are medically unexplained and attributed to psychological causes. Most NES involve a period of impaired consciousness and amnesia. Some patients with NES experience symptoms which also occur in panic attacks but panic attacks do not cause loss of consciousness.
The overwhelming majority of NES are considered as beyond patients’ voluntary control. NES are categorised under the dissociative or somatoform disorders in the current diagnostic manuals (ICD-10, DSM IV).
Epidemiology
There are no studies which have accurately measured the incidence or prevalence of NES in the general population. The highest quality epidemiological studies were based at tertiary epilepsy referral centres and have only described the frequency of video-EEG proven NES. These studies are likely to underestimate the true number of patients with NES. Bearing this in mind, the following facts have been reported:
· The incidence (the number of new cases) of video-EEG proven NES has been reported as 1.4/100,000, or 3/100,000/year.
· The prevalence (the total number of cases of a disease in a given population at a specific time) of NES has been estimated as between 2 and 33/100,000, illustrating the uncertainty noted above.
· In most patients, there is a delay of several years between the start of NES and the correct diagnosis.
· NES are more common in women; typically there is a 4:1 ratio of female to male patients with the disorder.
· NES typically start in the second or third decade of life, although a seizure onset in children below age ten and adults above seventy has been described.
Diagnosis
The diagnosis of NES and other seizure disorders is often a gradual process rather than a single event. The information available to clinicians about a first seizure is often limited. The diagnosis may become clearer as more events are observed and described. Most patients with NES are initially misdiagnosed as having epilepsy. In many patients the diagnosis of NES is made on clinical grounds alone (for instance because of a typical seizure history). Sometimes NES cannot be proven by video-EEG because seizures are too infrequent or fail to occur in hospital. Even if a NES has been recorded by video-EEG, this does not prove that all previous seizures were also NES. However, studies using prolonged video-EEG monitoring have found that only 5-10% of patients have NES and additional concurrent epileptic seizures. Nevertheless the diagnosis is “very probable” rather than “completely certain” in many cases. The following section briefly describes the most important diagnostic methods.
Diagnostic methods
· Although NES resemble epileptic seizures there are small but important differences in how patients and witnesses describe these different seizure types. Experts can make a correct diagnosis on the basis of factual and conversational features in at least 80% of patients. Factual features are observations such as the duration of seizures, the situations in which seizures have occurred, the precise nature of movements during seizures or whether the eyes and mouth were open or closed. Conversational features include the observation whether patients focus on their symptoms during the seizures or the situations in which seizures occur and seizure consequences when they talk to their doctor.
· Seizure experts can accurately differentiate between NES and other causes of attacks if they have access to a video recording of a seizure. They would also be expected to diagnose NES correctly if they had observed a seizure directly and examined the patient during the seizure.
· Video-EEG involves the simultaneous observation of the patient’s behaviour and their EEG. This test is highly reliable in the distinction of epilepsy and NES if the recording is analysed by an expert and if the recorded seizure involved impairment of consciousness. This test can only be considered diagnostic if the observed seizures were like the seizures which have happened spontaneously before the test. For this reason, the patient and a seizure witness should confirm that the recorded attack was typical. Seizure provocation techniques (such as hyperventilation, photo stimulation or the injection of saline placebo) are sometimes used to increase the yield of video-EEG.
· A scalp EEG recording of an epileptic seizure can reliably exclude most types of epilepsy. Normal ictal scalp EEG recordings cannot be considered diagnostic of NES if the seizure only produced subjective symptoms (such as tingling or anxiety). Scalp EEG recordings are also normal in some epileptic seizure of frontal lobe origin (for instance seizures with cycling movements or bilateral posturing).
· Blood tests immediately after a seizure (prolactin, creatine kinase) can provide some indication of the diagnosis of NES or epilepsy, especially if the seizure looked like a tonic-clonic (grand mal) seizure.
Predisposing, Precipitating and Maintaining Factors
A number of factors have been identified as possible causes of NES. The framework on page 12 gives an overview.
Predisposing Factors
All studies of predisposing factors such as stressful experiences, childhood neglect or trauma in patients with NES have been retrospective. Many were small and did not take clear account of the base rates of such experiences in the general population, or control for gender differences between NES and control groups. Studies of personality factors and of other psychopathology were typically carried out in patients who had experienced NES for several years. This makes it difficult to understand the relationship between NES and other emotional or behavioural symptoms. Like the studies of childhood trauma or neglect, the results of these studies may have been affected by the fact that more chronic or difficult seizure disorders were probably over-represented in the specialist centres where the research was carried out. Most studies of cognitive factors used test batteries designed for patients with epilepsy. The majority did not include tests of motivation, making the results difficult to interpret. However, the following findings have been reported:
Stressful experience
Around 90% of patients with NES report significant traumatic experiences in their past.
· Around 90% of patients with NES report that they have experienced the kind of events in the past which can be considered stressful enough to cause ongoing emotional problems.
· The most widely studied form of traumatic experience is childhood sexual and physical abuse.
· The reported rates of sexual or physical abuse in patients with NES vary widely, but the best quality studies have found that around 25% of women with NES report some form of early life abuse. Abuse is reported much less commonly by men with NES.
Family dysfunction
· It has been argued that NES are not so much a direct consequence of childhood abuse, but that both NES and childhood abuse are the result of family dysfunction.
· Small studies suggest that patients with NES are more likely to have been exposed to childhood neglect than control populations.
· NES patients are also more likely than patients with epilepsy to report a family history of psychiatric disorder or epilepsy.
· Some studies have suggested that NES patients experience their families as less supportive and communicative than patients with epilepsy or that their families are characterized by high levels of criticism and stronger somatisation tendencies.
Personality Factors
· NES disorders are not associated with one particular personality profile.
· Some NES patients have a personality profile resembling that of patients with borderline personality disorder.
· A further subgroup has a personality profile characterised by an unusually tight control of emotional regulation.
Psychopathology
· NES are associated with high levels of psychiatric co-morbidity. Common co-morbid disorders include;
o Somatoform disorders
o Dissociative disorders
o Post-traumatic stress disorder
o Depressive disorders
o Anxiety disorders
· The severity of psychopathology measured by self-report questionnaires correlates positively with the severity of the NES disorder.
Illness perceptions
· An important subgroup of patients with NES has difficulty recognising psychological influences on their disorder.
· They are less likely than patients with epilepsy to endorse stress or emotional factors as a possible cause of seizures.
· Many patients score as alexithymic (deficiency in understanding, processing, or describing emotions) on a self-report instrument.
Cognitive factors
· Many studies show that patients with NES tend to perform below expectation in tests of memory, attention and mental processing.
· However, most researchers have failed to identify a characteristic pattern of deficits in patients with NES.
Precipitating factors and seizure triggers
All studies of stress, life events or dilemmas as precipitants of NES are retrospective. Most do not compare the findings in NES patients with those in controls. Many patients report that (some of) their seizures are triggered by particular stimuli. However, there are no high quality studies of trigger factors. Bearing these limitations in mind, the following observations have been made.
Stress and dilemmas
· Many NES patients experience stress, or unresolvable dilemmas in their home environment.
· NES have been reported as developing after a whole range of life events: rape, injury, ”symbolic“ traumatic experience in adulthood after childhood abuse, surgical procedures, giving birth and undergoing anesthetics, death of or separation from family members or friends, job loss, road traffic and other accidents, earthquakes, relationship difficulties, and legal action.
· Many NES disorders do not start soon after a particular negative life event or experience. One small study in which patients were interviewed soon after seizures had first started, showed that (whilst patients with NES reported more negative life events over all than patients with epilepsy) there was no higher incidence of such events within the three months before seizure manifestation, although patients did report more negative life events overall.
Triggers for seizure recurrence
· Some recurrent seizures can be triggered by much less significant events or stimuli, for instance visits to the doctor, sudden noise or flashing light.
· In around two thirds of patients, NES can be provoked during (video-) EEG monitoring by a range of suggestion or provocation techniques.
· NES have also been reported from EEG-documented sleep, although NES from “pseudosleep” (apparent sleep with EEG appearances of wakefulness) are much more common.
· Very rarely, NES can be triggered by simple partial epileptic seizures.
Maintaining factors
Several studies have examined the healthcare use of patients with NES. Although it may be likely that suboptimal communication between patients and healthcare providers can contribute to bad treatment outcomes, the role of healthcare contacts as an aetiological factor remains unproven. Existing work in this area may have been influenced by the fact that most studies have been carried out in patients with relatively chronic seizure disorders presenting to specialist centres. Other possible maintaining factors such as financial illness benefits are very difficult to study. Nevertheless the following findings have been published:
Healthcare contacts
· Many patients with NES are frequent users of healthcare services.
· Patients with NES often have other medically unexplained physical symptoms including chronic pain, fibromyalgia, irritable bowel syndrome or menstrual problems.
· Frequent healthcare contacts mean that some patients are being repetitively investigated and hear different explanations from the many doctors they encounter.
Social / financial illness gain
· It is possible that financial or social benefits related to the seizures play a perpetuating role in some cases.
· Some patients may acquire a “sick role“ and off-load unpleasant responsibilities onto others. However, there is no systematic evidence suggesting that this is more common in NES patients than in those with other medical or psychological conditions.
· There is no evidence that malingering or the exaggeration of symptoms is seen more commonly in patients with NES than in patients with medically explained disorders.
Behaviour Change/Avoidance
· Avoidance is common in NES. Patients often stop doing activities they previously enjoyed or took part in because of the fear of having a seizure. This might be related to anxiety about what others might think, or fears about injury.
· Avoidance will typically lead to restrictions on the patient’s life over and above the level explained by physical disability.
Treatment
There is no high quality evidence for effective treatments for NES. A number of case reports, large uncontrolled studies and small controlled studies have been published. Many treatment suggestions are based on experience from the treatment of similar conditions such as somatoform disorder, dissociative disorder, or panic. The following statements can be made.