What are Non-Epileptic Seizures and how are they diagnosed?
Non-epileptic seizures (NES) are sudden, involuntary changes in behavior, motor activity, consciousness, sensation, or autonomic function, but unlike epileptic seizures, they do not involve abnormal electrical brain wave activity and cannot be explained by other neurological or medical conditions. NES are also called non-epileptic events, non-epileptic attacks, pseudoseizures , psychogenic seizures, dissociative seizures; the preferred term is NES. Below, we will call each episode of a NES an “event” to clearly distinguish them from epileptic seizures.
The diagnosis of NES is based on the clinical presentation ( semiology ) and confirmatory negative electrographic findings on video-electroencephalographic (video-EEG) monitoring that captures a typical event. There is no ‘ pathognomonic ' or diagnostic clinical sign or symptom that can reliably distinguish epileptic from non-epileptic events, although some clinical characteristics of the events could be ‘suggestive' of one diagnosis or the other. ‘Suggestive' signs of NES include thrashing movements of the entire body, opistotonic (back-arching) posturing of the trunk, moaning and crying ( Irirarte et al, 2003), out-of-phase oscillatory movements (Gates, 1985), eyelid closure especially at the onset of the event (Chung et al, 2005). Additionally, the clinical presentation can be pleomorphic or variable during NES. There is a variety of clinical features besides the ones described above that include autonomic signs and symptoms, other motor phenomena, altered responsiveness, loss of muscular tone, affective symptoms (such as fear, disgust, anxiety), experiental phenomena (elaborate accounts of perceptual, mnesic and affective components), sensorial symptoms (dizziness, derealization , depersonalization, unelaborated visual and auditory sensations), somatosensory symptoms, language disturbances, other vague feelings ( Galimberti et al, 2003 and Goldstein and Mellers , 2006). As mentioned earlier, no specific type of symptoms can reliably establish the etiology of the event although the presence of some signs and other characteristics of the events (longer duration, lack of post-event confusion) can be highly suggestive.
Non-epileptic events should also be distinguished from other physiological paroxysms (sometimes labeled ‘physiological' non-epileptic events); their accurate diagnosis will lead to a completely different treatment plan and these should always be considered when evaluating patients with suspected NES. These conditions include cardiogenic and noncardiogenic syncope ( ie : vasovagal responses), transient ischemic attacks, some migraine presentations, narcolepsy, parasomnias , intermittent movement disorders, paroxysmal vertigo, etc. (Trimble, 2001).
In addition to the clinical presentation, video-EEG monitoring that captures a typical event with no electrographic findings suggestive of epilepsy can help establish the diagnosis. As a matter of fact, video-EEG monitoring has been considered the ‘gold standard' in NES diagnosis for the last two decades. Without negative electrographic findings during a typical event in video-EEG, the specificity of diagnosing NES by history alone is established at about 50% ( Parra et al, 1999).
Although the existence of video-EEG is undoubtedly advantageous, it does not come with some limitations: many simple partial seizures and frontal lobe seizures might not show helpful ictal patterns with scalp electrodes. Also, the use of interictal EEG, although valuable, cannot reliably establish a connection between an actual event or seizure and the EEG discharges.
Many people with NES might have more than one type of event or clinical presentation and some people can also suffer from comorbid epilepsy and NES. Hence, when performing video-EEG monitoring, it is of utmost importance to have someone determine if the captured event is the ‘typical' event or if there are more types of events. Witnesses to the events ( ie : relatives or friends familiar with these episodes) are important for this task as well as for the clinical description of the events.
If they are not epileptic, where are NES coming from?
The short answer to this question is: it is not well-understood how NES originate. The best accepted hypothesis is that they are ‘psychogenic' in origin. This basically means that NES are considered the expression of some emotion recognition and management problem, even when the distressing factors and the emotional problems remain outside of the awareness of the patient. NES tend to occur in the context of stress and anxiety although some times no stressors can be identified.
It is very important for the patient to understand that the fact that the events are non-epileptic does not imply that they are voluntarily fabricated. There are some predisposing risk factors well established in the literature ( comorbid medical, neurological or psychiatric conditions, childhood experiences, personality traits, intellectual disability, illness representations) but none of them are sufficient to explain the development of NES. The same can be said about precipitating factors (such as new illnesses, life events, relationship conflicts) and perpetuating factors (specifically cognitive and behavioral factors) ( Chalder , 2001; Reuber , 2008).
How common are NES and how can they impact a person's life?
The incidence of NES is 1.4-3.0 per 100,000 in population studies (Davis, 2004). In the US alone, it is estimated that 300,000 to 400,000 people suffer from NES; it is also estimated that 5-20% of the 2.5 million people treated for epilepsy have comorbid NES (Martin et al, 1998; Martin et al, 2003); and 20% of patients referred to tertiary epilepsy centers suffer from NES (Davis, 2004).
The lifetime cost of treating NES for individual patients is estimated at $100,000 (Martin et al, 1998).
The benefit of early recognition is not only economic, but it can have a profound impact in the patient's quality of life. Early recognition can also reduce iatogrenic complications including drug toxicity, emergency interventions and even death (LaFrance and Barry, 2005). Earlier recognition of the non-epileptic origin of the events has been documented to be a positive prognostic factor when it comes to treatment outcome (Bowman and Kanner , 2007).
Can people with NES suffer from other psychiatric and neurological disorders?
Many people with NES suffer from other psychiatric and neurological disorders that may include one or more of the following: depression, anxiety disorders (including post-traumatic stress disorder), dissociative disorders, somatoform disorders, eating disorders, personality disorders (Bowman and Kanner , 2007; Bowmand and Markand , 1996), epilepsy, learning disabilities ( Reuber , 2008), migraine and other types of headache, chronic pain syndromes (LaFrance and Barry, 2005). A comprehensive evaluation for NES should always include a screening of these comorbid conditions.
Many leading authorities in NES have expressed that NES are just one manifestation in a continuum of psychopathology that might include very different expressions throughout the lifetime (LaFrance and Barry, 2005).
What treatments exist for NES?
Once the existence of NES is established, discussing the findings with the patient and, when pertinent, with his or her family, is the first therapeutic step. Many times this has already been initiated by the referring epileptologist . It is important, however, to have this discussion again once a more detailed assessment of the patient's psychiatric and medical comorbidities has been completed. There is literature specifically addressing this issue of “diagnosis presentation” as the very first step for the patient to accept treatment (Shen et al, 1990).
The goals for the treatment of NES need to be clear from the beginning. Although most patients envision the treatment making them NES-free, it is important to broaden the goals and establish priorities. Event reduction (in both frequency and severity) is always a goal but this can take time and treatment might not always lead to complete event control. Instead, improvements in quality of life and social functioning, decrease in medical utilization and unnecessary iatrogenic complications and addressing psychiatric comorbidities should be considered primary goals (La France and Barry, 2005) of equal importance during the treatment of NES.
The current evidence for treatment of NES is limited by the number of studies, small samples and open-label design (Brooks at al, 2007). A promising approach that has shown good evidence in an open-label study is cognitive-behavioral therapy (CBT) (Goldstein et al, 2004). Currently studies using CBT are being conducted at Maudsley Hospital (London, UK – information from clinicaltrials.gov) and Rhode Island Hospital (Providence, RI). Other types of psychotherapies such as group therapy, hypnosis, psychodynamic psychotherapy and family therapy have been studied in small, open-label studies, some in inpatient and some in outpatient settings (LaFrance et al, 2007).
No robust evidence exists supporting the use of pharmacological interventions to treat NES, although psychiatric comobordities commonly encountered in NES usually necessitate pharmacological treatment. A NINDS-supported double-blind, placebo-controlled study is being conducted at Rhode Island Hospital evaluating the antidepressant sertraline (information from clinicaltrials.gov).
References
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