Non-epileptic seizure

Non-epileptic seizures are paroxysmal events that resemble epileptic seizures but are not caused by abnormal electrical discharges in the brain. They are not a single condition, but a descriptive category encompassing multiple disorders that can produce seizure-like episodes without the electrical activity that defines epilepsy. Some may arise from functional disruptions in brain activity, as seen in psychogenic non-epileptic seizures – a common subtype classified under functional neurological disorders. Others result from physiological causes, including fainting, sleep disorders, or movement disorders, which can mimic epileptic seizures despite distinct mechanisms.
Non-epileptic seizures do not respond to anti-seizure medications. The gold standard for distinguishing them from epilepsy is video-electroencephalographic monitoring. Management depends on the underlying cause: functional seizures are treated with psychological and rehabilitative therapies, while physiological mimics require targeted medical care.

Terminology

Older terms such as pseudoseizure are now considered outdated and potentially pejorative. They have been discouraged by professional societies, including the International League Against Epilepsy, due to their implications of falsification or triviality.

Classification

Non-epileptic seizures are classified according to their underlying mechanism. While they all present with seizure-like symptoms, their causes vary widely. Broadly, NES are divided into two categories: functional seizures and physiological non-epileptic events.

Psychogenic non-epileptic seizures

The most common type of non-epileptic seizure encountered in neurology clinics is the functional seizure, also known as a psychogenic non-epileptic seizure or dissociative seizure. These events are classified as a subtype of functional neurological disorder, in which normal brain networks may be disrupted without structural damage or epileptic activity. Functional seizures are involuntary and may be associated with psychological distress, trauma, or dissociation, though not all patients have identifiable psychiatric conditions. The events often involve complex motor behaviors, unresponsiveness, or convulsions, and are frequently mistaken for epilepsy.

Physiological non-epileptic events

Other seizure-like episodes are caused by physiological processes unrelated to brain network dysfunction. These include:

Circulatory causes:
* Reflex anoxic seizures – brief asystole triggered by pain or fright, typically in young children
* Breath-holding spells – apnea and collapse following crying or frustration, common in toddlers
* Syncope – fainting from transient cerebral hypoperfusion
Sleep-related disorders:
* Parasomnias – sleepwalking, night terrors, or confusional arousals
* Narcolepsy with cataplexy – sudden muscle tone loss during wakefulness, often emotion-triggered
* REM sleep behavior disorder – dream-enactment movements during REM sleep
Movement and neurological disorders
* Tics – repetitive, often suppressible motor or vocal behaviors
* Paroxysmal kinesigenic dyskinesia – brief dystonic episodes triggered by sudden movement
* Hyperekplexia – exaggerated startle reflex with stiffness or falls
* Non-epileptic myoclonus – isolated muscle jerks without epileptiform discharges
Other mimics
* Migraine variants – especially basilar or hemiplegic types, with transient neurologic symptoms
* TIAs – brief focal deficits without convulsive movements
* Opsoclonus myoclonus syndrome – chaotic eye movements with myoclonus, often post-infectious
* Hypoglycemia – low blood sugar causing confusion or collapse

These events are sometimes referred to as organic non-epileptic seizures, though this terminology is less common. Their mechanisms are diverse – ranging from impaired cerebral perfusion to disrupted sleep physiology – but none involve the epileptiform activity that defines epileptic seizures.

Signs and symptoms

NES are defined by their resemblance to epileptic seizures. These events may involve convulsive movements, altered awareness, unresponsiveness, or sudden collapse, and are often difficult to distinguish based on appearance alone. The specific symptoms vary depending on the underlying cause – whether functional or physiological. However, some general features may help raise suspicion for a non-epileptic event:

Variable duration and motor patterns between episodes
Unusual movements
Eye closure during convulsions
Emotional triggers or context-specific occurrence
Lack of postictal confusion despite prolonged unresponsiveness
Resistance to anti-seizure medications

Diagnosis

The diagnosis of NES requires careful evaluation, as these episodes can closely resemble epileptic seizures. Because treatments differ significantly, distinguishing NES from epilepsy is essential to avoid misdiagnosis and inappropriate use of anti-seizure medications. The gold standard for diagnosis is video-electroencephalographic (video-EEG) monitoring, which allows for simultaneous recording of behavior and brain activity. Additional tests may be performed depending on the suspected underlying cause. These can include electrocardiography or tilt-table testing to evaluate for syncope, sleep studies for suspected parasomnias or narcolepsy, metabolic panels to identify electrolyte or glucose abnormalities, and neuroimaging to rule out structural brain lesions. Neuropsychological assessment may be useful in individuals with functional seizures, particularly when there is concern for cognitive or psychiatric comorbidities.

Management

For physiological causes of non-epileptic seizures, treatment is directed at the underlying medical condition precipitating the episodes. For functional seizures PNES, management focuses on clear communication of the diagnosis and a multidisciplinary approach. Functional seizures are treated with evidence-based psychological therapies. Cognitive behavioral therapy has the strongest evidence to date, with additional support for trauma-focused therapies and physical rehabilitation approaches. Educating the patient about the diagnosis in a validating, non-stigmatizing way is a critical first step. Discontinuation of anti-seizure medications may be appropriate if epilepsy has been excluded.