A seizure is defined as a sudden, uncontrolled electrical disturbance in the brain that causes changes in behavior, movements, feelings, or consciousness. Because seizure symptoms often involve dramatic, involuntary movements or loss of awareness, many other medical events are easily mistaken for this neurological condition. Differentiating a true epileptic seizure from a seizure mimic is an ongoing challenge in medicine. An incorrect diagnosis can lead to years of ineffective treatment with anti-seizure medications. Understanding the differences between an epileptic event and a non-epileptic event is the first step toward receiving the correct diagnosis and effective care.
Psychogenic Non-Epileptic Events
Psychogenic Non-Epileptic Events (PNEEs), also known as functional seizures, are the most difficult seizure mimics to distinguish from true epilepsy. These events are not caused by abnormal electrical firing in the brain but by underlying psychological distress, often related to trauma, anxiety, or stress. PNEEs are genuine, involuntary attacks that can manifest with convulsive movements, staring, or unresponsiveness.
PNEEs often exhibit specific characteristics that differ from epileptic seizures, which can be observed by a witness. The movements frequently appear asynchronous, meaning the limbs shake or flail out of rhythm, and may involve features like pelvic thrusting or side-to-side head movements. A person experiencing a PNEE may also keep their eyes closed tightly or resist eye opening, which is uncommon during a tonic-clonic epileptic seizure.
The duration of these events is another differentiating factor, as PNEEs typically last much longer than true seizures, often continuing for 10 to 30 minutes, while most epileptic seizures are brief. Following the event, individuals with PNEEs usually do not experience the prolonged post-seizure confusion or deep exhaustion (post-ictal state) common after an epileptic event. The definitive diagnosis relies on video-EEG monitoring, which captures the event while simultaneously recording normal brain wave activity, confirming the absence of an electrical discharge.
Events Caused by Circulatory Issues
Syncope, commonly known as fainting, is a widespread circulatory event frequently mistaken for a seizure, particularly when it includes jerking movements. Syncope occurs when a sudden, temporary reduction in blood flow to the brain deprives the organ of the oxygen and glucose it needs to function. This brief cerebral hypoperfusion causes a transient loss of consciousness and postural tone, leading to collapse.
The feature that causes confusion is “convulsive syncope,” where the lack of blood flow triggers brief, involuntary muscle jerks, known as myoclonus, after the loss of consciousness. These movements are usually limited, often fewer than 10 jerks per episode, and are not the sustained, symmetrical, rhythmic convulsions seen in a generalized tonic-clonic seizure. Syncope is typically preceded by warning signs such as lightheadedness, nausea, sweating, or visual dimming (presyncope), which are usually absent before a sudden epileptic seizure. Recovery from syncope is swift, often within seconds or a minute of lying down as blood flow is restored, though the person may feel weak or nauseous afterward.
Involuntary Movement and Sleep Disorders
Certain neurological and sleep-related conditions can involve movements that look like seizure activity but stem from entirely different mechanisms. Severe movement disorders, such as dystonia, involve sustained or repetitive muscle contractions that result in twisting or abnormal postures. An acute dystonic reaction, sometimes triggered by certain medications, can cause bizarre, dramatic movements that are visually misinterpreted as a focal seizure. Unlike a seizure, these movements can sometimes be temporarily suppressed with voluntary effort or special sensory tricks, and they do not correspond to an epileptic electrical discharge in the brain.
Sleep disorders, known as parasomnias, are a common source of nocturnal seizure mimics because they involve complex behaviors arising from sleep. Parasomnias like confusional arousals or night terrors occur during non-rapid eye movement (NREM) sleep and can include screaming, thrashing, or complex motor activity. These episodes tend to be longer than brief nocturnal seizures, and upon waking, the person may be confused or have partial memory of the event, distinguishing them from the stereotyped, unconscious movements of nocturnal epilepsy.
Systemic and Metabolic Triggers
The brain relies on a stable internal chemical environment, and any significant disruption to the body’s balance can cause neurological symptoms that mimic a seizure. Hypoglycemia, or severely low blood sugar, is a common metabolic trigger because glucose is the primary fuel source for brain cells. When glucose levels drop too low, brain function is impaired, leading to symptoms like confusion, unresponsiveness, or even convulsive activity.
Significant electrolyte imbalances can similarly destabilize the electrical activity of neurons. For instance, hyponatremia (low sodium levels) can cause the brain to swell and trigger seizure-like events by disrupting the ionic gradients necessary for normal nerve signaling. Severe systemic issues, such as acute intoxication or withdrawal from alcohol or sedatives, also cause widespread neurochemical disruption that lowers the seizure threshold.