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PubMed This is a summary of 30 peer-reviewed journal articles Updated
Neurology · Seronegative Autoimmune Encephalitis

What Seizure Types Occur in Seronegative Autoimmune Encephalitis?

At a Glance

Seronegative autoimmune encephalitis can cause focal aware, focal impaired-awareness, focal-to-bilateral tonic-clonic, and nonconvulsive seizures. Persistent confusion or reduced responsiveness may require urgent evaluation and continuous EEG to detect ongoing electrical seizures.

In this answer

4 sections

01

Emergency Checklist: When to Call for Help

02

Types of Seizures in Seronegative AE

03

Seizure First Aid and Rescue Medications

04

The Role of EEG Monitoring

Supratentorial seronegative autoimmune encephalitis (AE) is a condition where the immune system causes inflammation in the brain’s cerebral cortex. “Seronegative” simply means that standard tests did not find a currently recognized antibody, but the autoimmune disease and its symptoms are very real [1].

This brain inflammation can cause seizures in many patients [1]. It is important to know that anti-seizure medications treat the electrical symptom, but treating the underlying brain inflammation requires immunotherapy; do not change your medication doses without your doctor’s guidance [2].

Because seizures can take many forms—from dramatic convulsions to subtle periods of altered awareness—knowing how to recognize and respond to them is critical for your safety.

Emergency Checklist: When to Call for Help

Work with your medical team to create a written seizure action plan. Call your local emergency number (such as 911) immediately if [3][4]:

  • A convulsive seizure lasts 5 minutes or longer.
  • The person has trouble breathing, or their lips turn blue [5].
  • The person does not wake up or return to their usual baseline awareness after the convulsions stop [6].
  • It is a first-ever seizure, it occurs in water, or the person is injured.
  • Stroke Warning: The person suddenly develops an inability to speak, facial drooping, or weakness on one side of the body. Do not assume this is just encephalitis or a seizure—seek emergency stroke evaluation immediately [3].

Types of Seizures in Seronegative AE

Focal Aware Seizures

Previously called “auras,” these start in one area of the brain while you remain fully conscious. Because seronegative AE often involves the temporal and limbic brain regions (which process memory, emotion, and automatic bodily functions), you might experience [7]:

  • Sensory and autonomic changes: Sudden goosebumps, a racing heart, flushing, or strange unexplained smells and tastes [8][7].
  • Psychic symptoms: Intense feelings of déjà vu, unprovoked fear, or a sense of detachment [8].

Focal Impaired-Awareness Seizures

If the seizure alters your consciousness, it is called a focal impaired-awareness seizure. You may look awake but be unable to respond normally. Symptoms can include:

  • Automatisms: Repetitive, unconscious movements like lip-smacking, chewing, picking at clothes, or wandering [9].
  • Language arrest: Suddenly being unable to speak or understand words [10]. (Note: Language arrest can also happen while you are fully aware).
  • Unusual behavior: Brief episodes of agitation or appearing “frozen” [11].

It can be difficult to tell if confusion or unusual behavior is caused by the background brain inflammation itself or by an active electrical seizure. Because they look similar, medical assessment and brain wave monitoring are needed to tell them apart [12].

Focal to Bilateral Tonic-Clonic Seizures

Focal seizures can spread to both sides of the brain, causing what is commonly known as a generalized convulsion [7]. This involves a sudden loss of consciousness, muscle stiffening, and rhythmic jerking [13].

Nonconvulsive Seizures and Nonconvulsive Status Epilepticus (NCSE)

A serious, sometimes difficult-to-recognize complication is nonconvulsive status epilepticus (NCSE), where ongoing electrical seizures happen without obvious physical convulsions [14].

  • Observable signs: A person in NCSE may simply appear persistently confused, overly sleepy, or uncommunicative [15]. Sometimes there are subtle clues, like rhythmic eye-tracking movements or tiny facial twitches, but observation alone cannot rule NCSE in or out [9].
  • Post-convulsion risk: After a convulsion stops, some confusion is expected. However, if the person fails to steadily improve or their awareness remains altered for a prolonged period, it warrants urgent medical evaluation to ensure silent seizures are not continuing [16].

Seizure First Aid and Rescue Medications

During a Seizure

  • Time the event: Check the clock the moment the seizure begins [17].
  • Keep them safe: Clear the area of hard or sharp objects [17].
  • Do not restrain: Never hold the person down [18].
  • Nothing in the mouth: Never put a spoon, fingers, or oral pills into the mouth of someone having a seizure [19].
  • Record details: If safety is secured, a caregiver can record a brief video of the event (including eye movements and responsiveness) to show the neurologist.

After the Convulsions Stop

  • Recovery position: Gently roll the unresponsive person onto their side to keep their airway clear [20][21]. Do not force them onto their side during active convulsions [22].
  • Check breathing: If they remain unresponsive and are not breathing normally, commence CPR [5].

Using Prescribed Rescue Medications

For patients who experience seizure clusters (multiple seizures close together), doctors may prescribe a fast-acting rescue medication [23].

  • These are typically given as a nasal spray, a rectal gel, or a liquid placed inside the cheek—never as a pill to swallow during a seizure [24][25].
  • Use these exactly as trained. Because these medications can cause marked sedation and slow breathing, your written plan must specify the exact dose, when it is safe to give, and when to call emergency services if the seizures do not stop [25][6].

The Role of EEG Monitoring

An electroencephalogram (EEG) is a test that measures electrical activity in the brain. It is a critical tool for detecting nonconvulsive seizures [26][27].

  • A routine short EEG (usually 30 minutes) might miss seizures that happen intermittently [28].
  • If altered mental status persists or NCSE is suspected, the treating team will often consider continuous EEG (cEEG) monitoring to properly assess the brain’s electrical activity over hours or days [29][30].

Common questions in this guide

What types of seizures can occur with seronegative autoimmune encephalitis?
Seronegative autoimmune encephalitis can cause focal aware seizures, focal impaired-awareness seizures, and focal-to-bilateral tonic-clonic seizures. It can also cause nonconvulsive seizures or nonconvulsive status epilepticus, which may occur without obvious shaking.
How might a nonconvulsive seizure look?
A nonconvulsive seizure may look like ongoing confusion, unusual sleepiness, reduced responsiveness, or inability to communicate. Small facial movements or rhythmic eye movements can occur, but observation alone cannot confirm or exclude a seizure; an EEG is needed.
How can doctors tell whether confusion is from encephalitis or an ongoing seizure?
A neurologic assessment and EEG help determine whether abnormal electrical activity is causing the symptoms. A short routine EEG can miss intermittent seizures, so continuous EEG monitoring may be considered when altered awareness persists or nonconvulsive status epilepticus is suspected.
What should I do if someone with autoimmune encephalitis has a seizure?
Time the seizure, move hard or sharp objects away, and protect the person from injury without restraining them. Do not put anything in their mouth; after active convulsions stop, place an unresponsive person on their side and check breathing.
When should I call emergency services for a seizure?
Call emergency services if a convulsive seizure lasts five minutes or longer, breathing is difficult, the person does not return toward their usual awareness, or it is a first seizure, occurs in water, or causes an injury. Seek immediate stroke evaluation for sudden facial drooping, one-sided weakness, or new inability to speak.
How do anti-seizure medicine and immunotherapy work together?
Anti-seizure medicine helps control abnormal electrical activity, while immunotherapy treats the underlying brain inflammation. Do not change anti-seizure doses without medical guidance, and use any rescue medicine for seizure clusters only according to the written plan from the care team.

Related questions

Is Blood or CSF Better for Autoimmune Encephalitis? What Does CSF Show in Seronegative Autoimmune Encephalitis? Can Seronegative Encephalitis Have Normal MRI, CSF, EEG? How Can Autoimmune Encephalitis Happen Without Antibodies? Why Do Symptoms Fluctuate in Autoimmune Encephalitis?
Show more
Why Rule Out Infection Before Autoimmune Encephalitis? Can Seronegative Autoimmune Encephalitis Develop Slowly? Seronegative Autoimmune Encephalitis: Need a Brain Biopsy? Can Seronegative AE Cause Psychosis Without Seizures? Can Prior Treatments Cause False-Negative Antibody Tests? Can Seronegative Autoimmune Encephalitis Cause Symptoms? How Is Seronegative Autoimmune Encephalitis Distinguished? When Should Seronegative Encephalitis Treatment Begin? Seronegative AE: Is Cancer Screening Needed for Me? Should Autoimmune Encephalitis Antibody Tests Be Repeated? What Does Seronegative Autoimmune Encephalitis Mean? Seronegative vs Antibody-Positive AE: Is Prognosis Worse? When Is FDG-PET Useful After Negative MRI and Antibodies? Why Is Prolonged EEG Needed in Seronegative Encephalitis?

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This page is for informational purposes only and does not constitute medical advice. Your neurologist and care team should tailor your seizure action plan, rescue medication instructions, and emergency guidance.