Introduction

You may be familiar with epileptic seizures, perhaps having experienced an episode yourself or witnessed one. Seizures can be categorised into three main types: epileptic seizures, psychogenic non-epileptic seizures (PNES), and physiologic non-epileptic seizures. The latter two forms are triggered by psychogenic and physiologic factors, respectively.¹ Non-epileptic seizures (NES) resemble the symptoms of typical epileptic seizures but lack the abnormal electrical activity observed in epilepsy. They are time-limited episodic events that can involve motor, sensory, autonomic, and cognitive symptoms.²

Although NES present clinical differences from epileptic seizures, they are often diagnosed late or misdiagnosed due to difficulties in recognising and distinguishing the two conditions. Specific guidelines have been established, to aid physicians in accurately identifying the semiologic features of NES and elucidating the diagnostic criteria for this condition.

The differentiation of NES primarily relies on observing electroencephalography (EEG), which shows no epileptiform activity in the brain, despite the patient presenting symptoms associated with NES. Further tests for any underlying conditions, in combination with a comprehensive medical history of patients, are essential for accurate diagnosis.³

NES, particularly PNES, is a non-involuntary condition with somatic symptoms that can be exhausting for individuals. It affects patients worldwide, across all age groups, with those assigned female at birth (AFAB), and with a history of past abuse, being more likely to present the condition. Its prevalence is estimated at approximately 2-3.3 cases per 100,000.² Interestingly, 20%-30% of epileptic seizures are misdiagnosed PNES.⁴

What are non-epileptic seizures?

As previously mentioned, NES can be classified according to their origin into psychogenic and physiologic non-epileptic seizures.

Psychogenic non-epileptic seizures (PNES)

PNES are a type of functional neurological disorder/conversion disorder. They occur paroxysmally, with somatic and psychological symptoms similar to epileptic seizures, including abnormal behaviour and changes in consciousness. Major psychological stress or events, and the inability to express emotions, can trigger these symptoms in patients. PNES are often influenced by other psychiatric comorbidities like post-traumatic stress disorder (PTSD), depression, personality disorders, and anxiety.³ Symptoms of PNES are not considered typical of epileptic seizures but can include:^1,3

• Convulsions with abnormal movements
• Emotional distress such as crying or yelling
• Closed eyes
• Fluctuating rhythmic motions
• Asynchronous or side-to-side jerking movements
• Pelvic thrusting
• Subjective symptoms experienced by patients (e.g. dissociation, altered perception)
• Unresponsiveness
• Absence of confusion after the event
• Memory recall after the event

Physiologic non-epileptic seizures

Non-epileptic events of physiologic origin are caused by both neurologic and non-neurologic conditions that mimic epileptic seizures. Migraine, sleep disturbances, transient ischemic attack, and tremors can all induce non-epileptic episodes that may be mistaken for epileptic seizures. Additionally, metabolic problems and cardiac arrhythmias can also be associated with these events. 

An exact description of symptoms right before the event is crucial for distinguishing physiologic causes of non-epileptic episodes. For instance, the sensation experienced right before fainting may suggest syncope due to a heart condition, which may be mistakenly interpreted as an epileptic seizure, especially if tonic or clonic movements are present. A comprehensive medical history of patients and a detailed analysis of symptoms are crucial for an accurate diagnosis.⁵

How do non-epileptic seizures differ from epilepsy?

NES identification can be challenging due to their symptom similarities with epileptic seizures and hence cannot be diagnosed based solely on observational reports. A thorough analysis of all recorded semiologic signs is crucial for distinguishing NES and establishing an appropriate treatment plan. 

Some indicative symptoms of PNES include a prolonged duration and the characteristic symptoms mentioned above. In contrast, epileptic seizures are more likely to include symptoms such as self-injury (e.g. biting the tongue), memory loss, and pain after the event.⁶ Further physiological differences have been recognised between the two conditions with sinus tachycardia being less persistent and having a more gradual onset in NES compared to epileptic seizures.⁷ A summary of some suggestive signs and differences between PNES and epileptic seizures can be seen in the table below.^2,3,6,7

Diagnosis of non-epileptic seizures

The symptoms of NES can be variable, and patients should undergo further clinical investigation to accurately identify their condition. A thorough clinical assessment, considering various clinical factors and diagnostic tests is key in establishing the diagnosis of NES, particularly for PNES. Notably, early diagnosis can be challenging, as patients are often initially treated with antiepileptic drugs, and are only diagnosed with PNES after showing resistance to these agents.⁸

The initial observation of the semiological features of a seizure, either directly by clinicians present during the event or after reviewing a recording of it, is a determinant factor for identifying PNES. A medical psychiatric history of PTSD, trauma, personality disorders, and other functional and somatic symptom disorders should raise suspicion of PNES.

A prolonged video-EEG monitoring during a seizure is considered the gold standard for diagnosing PNES, as it confirms the absence of abnormal electrical activity during the event. However, recording a seizure during a video-EEG can be time-consuming and delay diagnosis, therefore, specific induction techniques can be utilised to trigger such events.⁴

Apart from psychiatric comorbidities, specific psychologic traits are often observed in PNES, such as the inability to cope or express emotions, an abnormal mental state, somatisation, and dissociative events. Finally, supplementary diagnostic procedures assisting in diagnosing PNES include various blood marker tests, neuropsychological tests, and neuroimaging tests using computed tomography (CT) and magnetic resonance imaging (MRI) scans.⁹

Management of non-epileptic seizures

NES do not respond to antiepileptic medications, and specific guidelines for the management of this condition have not yet been established. However, patients may present both epileptic and non-epileptic seizures, and thus the use of antiepileptic drugs may be indicated.⁹

A thorough medical history and clear communication of symptoms during a seizure, by patients themselves or witnesses, are key initial steps to NES management. Referring to an experienced professional who employs a positive and empathic communication strategy can enhance the efficacy of treatment.

Regarding NES of physiologic causes, resolving underlying conditions that may trigger such events is essential. In the case of PNES, the involvement of specialists is crucial, for instance, psychiatrists can evaluate potential psychiatric comorbidities–predominately observed in PNES–and recommend appropriate pharmacological treatment plans, such as antidepressant medications.¹⁰

Ultimately, patients should be fully committed to receiving help and adhering to long-term, tailored interventions. This involves engaging in psychotherapy and other approaches, such as cognitive behavioural therapy, for coping with psychiatric symptoms.⁹

Summary

NES are episodic events that mimic the symptoms of epileptic seizures but have distinguishing characteristics. Unlike epileptic seizures, NES do not present the electrical firing abnormalities of epileptic seizures, as observed in a video EEG recording. NES are classified according to their origin into physiologic or psychogenic causes. PNES are most commonly observed in individuals with preexisting psychiatric conditions, such as PTSD. Individuals AFAB with a history of trauma, like sexual abuse, have a higher likelihood of experiencing NES.

The semiological features of PNES are not well-established but differ from those of epileptic seizures in terms of duration, movements, and emotional responses. For instance, patients with PNES may exhibit asynchronous movements, emotional distress, closed eyes, and a sense of losing control while being cautious to avoid injury. These symptoms are insufficient for diagnosing PNES. Accurate diagnosis requires a comprehensive medical history, video-EEG surveillance, and the involvement of a multidisciplinary team, including psychotherapists.

NES can be significantly burdensome and debilitating for individuals. Management mainly relies on the use of pharmacological psychiatric therapy, but the patient’s ongoing commitment to engaging in psychotherapeutic programs and cognitive behavioural therapies is also crucial.