AUTONOMIC SEIZURES
When seizures affect automatic body functions
Not every epileptic seizure causes:
shaking
staring
collapse
or obvious loss of consciousness.
Some seizures primarily disturb the body's autonomic nervous system.
This is the system involved in regulating functions that normally happen without conscious control, including:
heart rate
blood pressure
breathing
sweating
skin colour
temperature responses
digestion
salivation
pupil size
and bladder function.
During a seizure, these automatic functions can temporarily change.
Someone might suddenly experience:
a racing heart
an intense rising feeling from the stomach
nausea
vomiting
sweating
goosebumps
flushing or pallor
altered breathing
dilated pupils
excessive saliva
or a sudden urge to urinate.
The International League Against Epilepsy recognises all of these as possible autonomic seizure phenomena.
Because many of these symptoms also occur in ordinary medical conditions, autonomic seizures can be particularly difficult to recognise.
What does “autonomic” mean?
The autonomic nervous system regulates many processes that the body performs automatically.
It has major roles in controlling:
the cardiovascular system
breathing
temperature regulation
digestion
bladder function
pupil responses
sweating
and other internal functions.
These processes are regulated not by one single “autonomic centre” but by a network of brain regions often described collectively as the central autonomic network.
That network includes structures involving:
the insula
amygdala
hypothalamus
cingulate cortex
medial temporal structures
prefrontal regions
brainstem
and interconnected cortical and subcortical areas.
When seizure activity enters these networks, autonomic function can change. A systematic review concluded that autonomic symptoms can be the predominant feature of a focal seizure or can accompany focal, generalised and unknown-onset seizures.
Has the terminology changed?
Yes.
Under the 2017 ILAE seizure classification, clinicians could describe a seizure as a:
focal autonomic seizure
when autonomic symptoms were the main early manifestation.
The 2025 ILAE seizure classification changed the structure.
There are now four main seizure classes:
focal
generalised
unknown whether focal or generalised
unclassified.
The newer system separates the biological seizure class from descriptive features of what happens during the seizure.
Autonomic signs are therefore listed as seizure-semiology descriptors, including cardiovascular, gastrointestinal, respiratory, cutaneous, pupillary and urinary phenomena.
So clinicians may still use expressions such as:
“focal seizure with prominent autonomic features”
or:
“autonomic seizure.”
But the full seizure classification should follow the current ILAE framework.
What autonomic symptoms can a seizure cause?
The 2025 ILAE classification lists a wide range.
Cardiovascular
tachycardia — increased heart rate
bradycardia — reduced heart rate
ictal asystole — temporary absence of effective heartbeats
Skin and temperature
sweating
flushing
piloerection — goosebumps
temperature sensations or changes
Epigastric and gastrointestinal
rising epigastric sensations
nausea
vomiting
abdominal sensations
flatulence
excessive saliva
spitting
Pupillary
miosis — constricted pupils
mydriasis — dilated pupils
Respiratory
apnoea
choking sensations
hyperventilation
hypoventilation
Urinary
urinary urgency
urinary incontinence.
These features may occur alone or as part of a seizure containing sensory, cognitive, emotional or motor features as well.
Autonomic symptoms may be the first clue that a seizure has started
A focal seizure may begin with something apparently unrelated to epilepsy.
For example:
sudden rising sensation in the abdomen
followed by:
fear
then:
loss of responsiveness and automatisms.
Or:
sudden nausea
followed by:
staring and impaired consciousness.
Or:
goosebumps and chills
followed by other focal seizure signs.
These early symptoms can provide important information about which networks the seizure is recruiting.
Sometimes the autonomic symptom is almost the entire seizure
Autonomic manifestations can occasionally occur with very little outward evidence of epilepsy.
Someone may repeatedly experience brief, stereotyped episodes of:
palpitations
nausea
sweating
chills
flushing
abdominal sensations
or breathing changes
without obvious convulsions.
If consciousness remains preserved and no one sees the event, the person may initially seek assessment for:
heart disease
panic attacks
gastrointestinal disease
endocrine problems
respiratory disease
or another non-neurological condition.
The ILAE semiology glossary specifically warns that seizures confined to autonomic symptoms can be mistaken for non-epileptic events.
Repetition and stereotypy can be important clues
An ordinary bodily symptom often varies from episode to episode.
A seizure tends to produce a more stereotyped pattern.
For example:
sudden identical rising stomach sensation → pallor → brief loss of responsiveness
occurring repeatedly may be more neurologically informative than non-specific occasional nausea.
Specialists consider:
how abruptly symptoms begin
whether episodes are similar each time
duration
what happens immediately afterwards
associated awareness or responsiveness
other seizure signs
EEG
and imaging.
No single autonomic symptom proves epilepsy.
The rising epigastric sensation
One of the best-known autonomic seizure experiences is the epigastric aura.
People describe it in many ways:
rising sensation in the stomach
butterflies
pressure
an empty feeling
nausea
movement rising towards the chest or throat
or an indescribable internal sensation.
Epigastric phenomena are especially familiar in temporal lobe epilepsy, although they are not exclusive to it. The ILAE semiology glossary identifies epigastric phenomena among clinically useful autonomic features.
An epigastric seizure symptom is not simply indigestion
The digestive tract can obviously produce many genuine gastrointestinal symptoms.
The clue to an epileptic event is not merely:
“something happened in the stomach.”
It is the wider pattern.
For example:
sudden stereotyped onset
short duration
repeated identical episodes
accompanying déjà vu or fear
altered consciousness
automatisms
or later EEG evidence
may increase suspicion of a seizure.
Persistent abdominal pain lasting hours would have a very different differential diagnosis.
Heart rate often increases during seizures
Changes in heart rate are among the most studied autonomic effects of epilepsy.
Ictal tachycardia means the heart rate increases during a seizure.
A review of 34 studies found significant seizure-associated heart-rate increases in a large proportion of people studied with simultaneous EEG and ECG. Across the literature reviewed, ictal tachycardia was reported in approximately 82% of patients, although frequency varied considerably between seizures, individuals and study methods.
The ILAE semiology review likewise identifies sinus tachycardia as the most common cardiovascular autonomic manifestation of seizures.
The heart-rate change can begin early
In some seizures, heart rate changes occur close to — or occasionally before — clear scalp EEG changes.
A systematic review and meta-analysis of nearly 3,000 seizures estimated detectable pre-ictal heart-rate increase in around 36% of seizures, although the evidence was highly heterogeneous and affected by study methodology.
This has encouraged research into heart-rate-based seizure detection.
But a racing heart is extremely non-specific.
It also happens with:
exercise
anxiety
pain
fever
dehydration
arrhythmias
and many other conditions.
Heart rate alone therefore cannot diagnose a seizure.
Seizure-detection technology sometimes uses autonomic signals
Researchers have investigated:
heart rate
heart-rate variability
oxygen saturation
electrodermal activity
ECG morphology
and combinations of these signals
for automatic seizure detection.
A systematic review found promising results from some multimodal systems but concluded that the evidence base was limited by small studies, short follow-up and false alarms.
So autonomic monitoring can contribute to seizure-detection systems.
It does not replace EEG or clinical assessment.
Some seizures slow the heart instead
Ictal bradycardia means the heart rate falls during a seizure.
It is far less common than ictal tachycardia.
Rarely, seizure activity can produce ictal asystole, where effective cardiac activity temporarily stops.
The ILAE semiology review estimates bradycardia and ictal asystole as uncommon compared with tachycardia.
A major systematic review of published ictal-asystole cases found that these events occurred in focal epilepsy and were particularly associated with temporal seizure networks.
Because this is a specialised and important subject, it belongs in its own Information Hub article.
Related Information Hub page:
Ictal Asystole and Seizure-Related Bradycardia
Ictal asystole can cause a second collapse
A focal seizure may begin first.
Then, if a substantial pause in cardiac output develops, blood flow to the brain can fall.
The person may subsequently:
lose muscle tone
become unresponsive
collapse
or develop movements associated with cerebral hypoperfusion.
One video-EEG study identified ictal asystole in approximately 0.27% of people with epilepsy undergoing long-term monitoring.
That is a specialist monitoring population rather than a universal prevalence estimate.
Ictal asystole remains rare.
Breathing can also change during seizures
Respiratory autonomic changes include:
faster breathing
slower breathing
hypoventilation
apnoea
obstructed breathing
choking sensations
and reductions in oxygen saturation.
The 2025 ILAE classification formally includes:
apnoea
choking
hyperventilation
and hypoventilation
among autonomic seizure phenomena.
Ictal central apnoea can occur in focal seizures
Ictal central apnoea means breathing temporarily stops because the brain's respiratory drive is disrupted during the seizure, rather than because the airway is physically blocked.
A 2025 review reported ictal central apnoea particularly in focal, especially temporal, seizures and summarised studies in which it occurred in approximately 36–40% of ictal events in selected monitored populations.
Those figures come from specialist epilepsy-monitoring research and should not be interpreted as meaning that more than one-third of all seizures in the community cause obvious apnoea.
The person may not realise their breathing stopped
One remarkable feature of ictal central apnoea is that some individuals appear to have little or no awareness of it.
Other seizure features may dominate their experience.
This means respiratory monitoring during video-EEG can reveal changes that neither the person nor observers recognised.
Breathing changes matter because oxygen can fall
Longer episodes of apnoea can lead to hypoxaemia — reduced oxygen levels in the blood.
The 2025 respiratory review describes hypoxaemia as an important consequence of prolonged ictal apnoea and highlights increasing research interest in peri-ictal breathing disturbances because of their possible relevance to seizure safety and SUDEP mechanisms.
That does not mean every brief breathing change signals imminent SUDEP.
The relationship is far more complex.
Autonomic seizures and SUDEP are related research areas — but they are not the same thing
Researchers study:
breathing
oxygen
heart rhythm
post-convulsive apnoea
and autonomic regulation
because cardiorespiratory dysfunction appears important in sudden unexpected death in epilepsy — SUDEP.
A contemporary cardiac review notes that ictal bradycardia/asystole and the mechanisms believed to underlie SUDEP are not necessarily the same process; current evidence particularly implicates central cardiorespiratory dysfunction following generalised tonic–clonic seizures in SUDEP research.
Someone having an autonomic symptom therefore should not assume:
“This means I am about to have SUDEP.”
Risk assessment requires the broader epilepsy context.
Sweating can be ictal
A person may suddenly develop:
sweating
clamminess
or localised perspiration
during a focal seizure.
Ictal sweating is uncommon as an isolated feature, but it is recognised in seizure semiology.
Because sweating also occurs with:
panic
low blood glucose
infection
pain
menopause
medication
and many other conditions,
its diagnostic value depends on the wider event.
Goosebumps can be a seizure symptom
Piloerection means the hairs stand upright, creating goosebumps.
This normally occurs in response to:
cold
fear
emotion
or temperature regulation.
Rarely, it can be generated by seizure activity.
A 2026 systematic review of cutaneous ictal signs found that piloerection had the strongest evidence among the skin manifestations examined and was frequently associated with temporal-lobe involvement in reported focal epilepsy cases.
However, most evidence came from relatively small studies and case reports.
Piloerection remains a supporting semiological clue, not a localisation test by itself.
Sometimes goosebumps are almost the whole seizure
Rare documented cases show how subtle autonomic seizures can be.
A 2026 case report described a person whose habitual seizures consisted largely of:
bilateral goosebumps
chills
and coughing.
Stereo-EEG demonstrated seizure onset in the right amygdala and hippocampus, and electrical stimulation of these regions reproduced the piloerection.
Cases like this demonstrate that an outwardly minor bodily phenomenon can occasionally represent genuine focal epilepsy.
They do not mean ordinary goosebumps should generally be treated as seizures.
Pallor and flushing can occur
Seizures can alter the autonomic control of blood vessels in the skin.
Someone may become:
unusually pale
flushed
or experience changes in facial colour.
A 2026 systematic review found associations between certain ictal skin signs and seizure localisation, including links between pallor and temporal involvement and between flushing and posterior seizure networks in the available literature.
The researchers also stressed limitations caused by small numbers and retrospective evidence.
Skin colour alone cannot establish seizure origin.
Feeling suddenly hot or cold can also be ictal
Some people report:
sudden heat
sudden cold
chills
shivering sensations
or a wave of temperature change
during focal seizures.
These are recognised thermoregulatory autonomic phenomena.
Older temporal-lobe epilepsy research has specifically documented stereotyped attacks of cold shivering and goosebumps associated with focal seizure activity.
Again, these symptoms have many common non-epileptic causes.
Stereotyped repetition and associated seizure features are essential context.
Pupils can change
The autonomic nervous system controls pupil size.
Seizure activity can therefore cause:
mydriasis — pupil dilation
or:
miosis — pupil constriction.
The 2025 ILAE classification includes both among recognised pupillary autonomic phenomena.
Pupil changes usually form only one part of the overall seizure picture.
They are also influenced by:
light
medication
drugs
eye disease
brain injury
and other neurological conditions.
Excessive saliva can be part of a seizure
Autonomic seizure activity can cause:
hypersalivation
sialorrhoea
spitting
or swallowing-related changes.
These phenomena are particularly associated with some:
temporal
insular
and opercular networks.
The ILAE lists hypersalivation and spitting within gastrointestinal/autonomic seizure semiology.
They should be interpreted alongside other symptoms rather than used alone for localisation.
Nausea and vomiting can be ictal
A seizure can itself produce:
nausea
retching
or vomiting.
The ILAE explicitly lists nausea/vomiting among gastrointestinal autonomic seizure phenomena.
These symptoms can also occur after seizures, particularly alongside postictal headache.
The timing therefore matters.
Related Information Hub page:
Nausea and Vomiting During Recovery
Urinary symptoms can be ictal too
The current ILAE classification recognises:
urinary urge
and urinary incontinence
as autonomic seizure phenomena.
Rare focal seizures can begin with a stereotyped sudden urge to urinate.
Incontinence is more familiar but is not specific to epilepsy and cannot distinguish epileptic seizures reliably from fainting or other events.
Related Information Hub page:
Bladder and Bowel Changes Around Seizures
Autonomic symptoms can occur in children
There is a recognised childhood epilepsy syndrome in which autonomic seizures are particularly prominent:
Self-Limited Epilepsy with Autonomic Seizures — SeLEAS.
It was historically called:
Panayiotopoulos syndrome
or early-onset benign occipital epilepsy.
Current ILAE syndrome classification uses SeLEAS.
What happens in SeLEAS?
SeLEAS generally begins in childhood, most commonly between approximately 3 and 6 years, although the recognised range is broader.
Seizures are usually infrequent.
Autonomic symptoms can include:
nausea
retching
vomiting
pallor
flushing
abdominal discomfort
pupil changes
cardiorespiratory changes
salivation
and incontinence.
Vomiting occurs in approximately 75% of affected children according to ILAE syndrome guidance.
SeLEAS seizures can be surprisingly long
More than 70% of SeLEAS seizures occur from sleep in the ILAE clinical description, and seizures can sometimes last for many minutes or longer.
Prolonged autonomic seizures can therefore initially be mistaken for:
gastroenteritis
migraine
fainting
poisoning
metabolic illness
or another acute medical problem.
SeLEAS deserves its own full syndrome article later in the Epilepsy Syndrome Library rather than being explained completely here.
Autonomic seizures are not only a childhood phenomenon
Adults can also experience focal seizures dominated by autonomic manifestations.
Examples include:
epigastric sensations
heart-rate changes
nausea
sweating
piloerection
respiratory phenomena
urinary urge
or combinations of these symptoms.
Autonomic seizure semiology therefore applies across age groups.
Temporal lobe seizures commonly produce autonomic phenomena
Many autonomic seizure manifestations are associated with temporal and mesial temporal networks.
This is partly because structures such as:
the amygdala
hippocampus
and surrounding limbic networks
have extensive connections with autonomic regulatory systems.
For example, ictal tachycardia is particularly frequent in temporal-lobe seizures in published research.
But:
autonomic symptom = temporal lobe epilepsy
is too simplistic.
The insula is particularly important
The insula is deeply involved in processing internal bodily sensations and autonomic regulation.
It contributes to perception of:
heartbeats
breathing
visceral sensations
nausea
pain
and other internal states.
Autonomic manifestations involving:
vomiting
throat sensations
cardiovascular changes
and other visceral symptoms
can occur when seizures arise from or spread through insular networks.
The ILAE semiology literature repeatedly identifies insular or insulo-opercular involvement with several autonomic phenomena.
But seizure symptoms do not always reveal where the seizure began
This distinction is fundamental.
A symptom may reflect:
the seizure-onset zone
or:
the network the seizure spread into.
For example, a seizure could begin in one temporal region and only later recruit autonomic networks responsible for nausea or heart-rate change.
Therefore even a strongly localising-looking symptom should be interpreted alongside:
EEG
MRI
video telemetry
chronology
neuropsychology
and other investigations.
Some autonomic signs have proposed lateralising value
Researchers have examined whether certain signs are more associated with one cerebral hemisphere.
Examples historically proposed include:
ictal vomiting
urinary urge
spitting
and some forms of piloerection.
But evidence is often based on relatively small series and can be inconsistent.
The ILAE semiology glossary therefore treats these as potential clues, not absolute rules.
A symptom can be valuable without being diagnostic
For example:
repeated stereotyped ictal vomiting
may help specialists build a hypothesis about seizure networks.
But it cannot replace:
EEG
imaging
or clinical assessment.
The same applies to:
pallor
piloerection
urinary urge
coughing
or other unusual autonomic features.
Seizure localisation is a process of concordance between multiple pieces of evidence.
Autonomic seizures can mimic panic attacks
Several autonomic seizure features are also classic symptoms of anxiety or panic:
racing heart
sweating
chest sensations
breathlessness
nausea
chills
fear.
A focal seizure may even include intense ictal fear at the same time.
That can make differentiation difficult.
Specialists consider:
stereotypy
abruptness
duration
alteration of consciousness
associated automatisms
post-event symptoms
EEG evidence
and the broader history.
Neither panic nor epilepsy should be diagnosed from a single symptom such as palpitations.
Heart disease can mimic autonomic seizures
An abnormal heart rhythm can cause:
palpitations
dizziness
altered vision
fainting
collapse
stiffening
and brief jerking.
That can closely resemble epilepsy.
A 2024 state-of-the-art review emphasises the importance of distinguishing cardiac syncope and arrhythmia from epilepsy and highlights combined EEG and ECG monitoring where appropriate.
Related Information Hub page:
Fainting, Heart Problems and Epilepsy Lookalikes
This is why ECG can matter in seizure assessment
An EEG measures electrical brain activity.
An ECG measures electrical heart activity.
They answer different questions.
For somebody whose events involve:
palpitations
fainting
unexplained falls
or possible rhythm abnormalities,
both may be relevant.
Video-EEG telemetry often includes simultaneous ECG precisely because neurological and cardiac events can overlap.
Gastrointestinal illness can mimic autonomic seizures
Repeated vomiting, nausea or abdominal discomfort may obviously arise from:
infection
reflux
gastrointestinal disease
migraine
medication
food intolerance
or other conditions.
A seizure becomes more plausible when episodes are:
very stereotyped
sudden
brief or predictably patterned
accompanied by other seizure features
or supported by EEG evidence.
SeLEAS is a classic example in children where seizure-related vomiting can initially be mistaken for gastrointestinal illness.
Migraine can overlap too
Migraine can cause:
nausea
vomiting
pallor
sensory changes
visual phenomena
and autonomic symptoms.
Epilepsy and migraine can also occur in the same person.
Timing, symptom evolution and neurological context therefore matter.
One autonomic symptom cannot determine which disorder is responsible.
Low blood sugar can look similar
Hypoglycaemia can produce:
sweating
pallor
tremor
palpitations
behavioural change
confusion
and eventually seizures.
This illustrates an important point:
an autonomic symptom may occur because of:
the seizure itself
or because of:
the medical condition causing the seizure.
Those are very different situations.
The same principle applies to infection and fever
A person with an infection may experience:
chills
sweating
flushing
rapid heart rate
vomiting
and eventually seizures.
Those symptoms are not necessarily seizure manifestations.
Chronology matters.
Clinicians need to ask:
Which symptoms occurred as part of the ictal event, and which were already present because the person was ill?
How are autonomic seizures diagnosed?
There is no single autonomic-seizure test.
Diagnosis may involve:
detailed history
eyewitness description
seizure diary
video
EEG
video-EEG telemetry
MRI
ECG
heart-rate monitoring
oxygen monitoring
and other investigations tailored to the symptom.
If cardiac events are possible, longer ECG monitoring may sometimes be required.
If respiratory manifestations are suspected, respiratory channels during specialist video-EEG can provide important information.
A normal routine EEG does not exclude them
As with other focal seizures, a routine scalp EEG may be normal between events.
Some seizures also arise from deep regions that are difficult to detect clearly at the scalp.
Diagnosis therefore cannot depend solely on:
“Did the routine EEG show a seizure?”
Related Information Hub page:
EEG — What It Can and Cannot Tell You About Epilepsy
Video telemetry can be especially useful
During inpatient video telemetry, clinicians can simultaneously record:
behaviour
scalp EEG
ECG
and, in some units, additional physiological channels.
This makes it possible to determine whether symptoms such as:
vomiting
tachycardia
apnoea
pallor
or unusual movements
occur at the same time as an electrographic seizure.
Related Information Hub page:
Video Telemetry — Recording Seizures in Hospital
Some autonomic changes are invisible without monitoring
A person might have:
substantial heart-rate acceleration
reduced oxygen saturation
or temporary breathing interruption
without describing any sensation.
Video alone may therefore miss part of the event.
This is one reason multimodal physiological monitoring is increasingly important in epilepsy research.
Wearables may detect some autonomic changes
Some devices monitor combinations of:
heart rate
electrodermal activity
movement
oxygen saturation
and other physiological signals.
Autonomic changes can potentially contribute to seizure detection.
But the 2019 systematic review of autonomic seizure-detection algorithms found that false-alarm rates and study quality remain significant limitations.
No consumer wearable should therefore be assumed to detect every autonomic seizure reliably.
What should be recorded?
If autonomic seizures are suspected, useful information includes:
exactly what the first symptom was
whether the sensation rose or moved
skin colour
sweating
goosebumps
nausea or vomiting
heart sensations
breathing changes
pupil changes
urinary symptoms
consciousness
responsiveness
subsequent movements
duration
recovery
and whether each episode follows the same sequence.
Chronology is particularly important under the 2025 ILAE classification, which emphasises describing the sequence of seizure manifestations rather than relying only on the first sign.
Record what was observed separately from what was felt
Some autonomic symptoms are subjective.
For example:
“My heart suddenly felt like it was pounding.”
Others can be observed:
pulse accelerated on ECG.
Similarly:
“I suddenly felt extremely hot.”
is different from:
visible facial flushing and sweating.
The ILAE semiology glossary specifically distinguishes subjective autonomic auras from objective autonomic signs.
Both can be clinically useful.
When can an autonomic symptom be an aura?
An aura is itself a seizure manifestation, usually experienced while the person can still report the symptom.
An autonomic aura might include:
epigastric sensation
palpitations
nausea
sudden temperature sensation
urinary urge
or another internal bodily change.
It may remain isolated.
Or the seizure may continue into:
impaired consciousness
automatisms
motor activity
or a bilateral tonic–clonic seizure.
Related Information Hub page:
Auras and Epilepsy — The Seizure Before the Seizure?
Autonomic does not mean “mild”
Some autonomic seizures are brief and relatively limited.
Others can produce important physiological changes.
Rare manifestations include:
prolonged apnoea
substantial oxygen desaturation
marked bradycardia
and ictal asystole.
So the absence of convulsions does not mean an event is automatically harmless.
At the same time, most ordinary autonomic sensations are not seizures.
Both points matter.
When do autonomic symptoms need urgent medical assessment?
Urgency depends on the symptom and circumstances.
Medical assessment is particularly important for:
new unexplained collapse
prolonged breathing cessation
significant breathing difficulty
blue or grey colour
prolonged loss of consciousness
severe chest pain
suspected serious heart-rhythm disturbance
repeated seizures without recovery
prolonged seizure activity
or a first unexplained event.
A known epilepsy diagnosis should not cause new cardiac or respiratory symptoms to be automatically attributed to seizures.
Palpitations should not automatically be labelled epilepsy
A person with epilepsy can also develop an independent heart problem.
If episodes involve:
prolonged palpitations
exertional symptoms
fainting
chest pain
or a family history of sudden cardiac death,
cardiac assessment may be necessary.
The brain and heart can produce very similar transient loss-of-consciousness presentations, which is why current reviews emphasise combined neurological and cardiac investigation when uncertainty remains.
Breathing changes deserve their own detailed page
Respiratory seizure phenomena are sufficiently important to deserve a dedicated Information Hub article.
That page can cover:
ictal central apnoea
obstructive apnoea
hypoventilation
oxygen desaturation
post-convulsive breathing changes
and their relationship with seizure safety and SUDEP research.
This page therefore introduces respiratory autonomic seizures without duplicating that later material.
Related Information Hub page:
Breathing Changes During Seizures
Heart-rhythm changes also deserve separate coverage
Likewise, the detailed questions surrounding:
ictal tachycardia
bradycardia
asystole
syncope
cardiac pacing
ECG monitoring
and seizure-versus-arrhythmia diagnosis
need their own specialist pages.
Related Information Hub pages:
Ictal Asystole and Seizure-Related Bradycardia
Seizure-Related Changes in Heart Rhythm
Fainting, Heart Problems and Epilepsy Lookalikes
Autonomic features can help specialists — but only in context
An unusual symptom may provide an important clue.
Examples include:
piloerection
ictal vomiting
urinary urge
pallor
or particular cardiorespiratory changes.
But modern epilepsy localisation does not rely on one symptom.
Specialists ask whether different sources of information are concordant.
That includes:
clinical semiology
scalp EEG
MRI
PET/SPECT/MEG where appropriate
neuropsychology
invasive EEG where necessary
and treatment outcome.
The most important message
Seizures can affect automatic body functions.
The 2025 ILAE classification formally recognises autonomic seizure phenomena involving:
the heart
breathing
skin and temperature
gastrointestinal function
pupils
and the urinary system.
These manifestations may include:
tachycardia
bradycardia
ictal asystole
flushing
sweating
goosebumps
epigastric sensations
nausea
vomiting
pupil changes
apnoea
hyperventilation
urinary urgency
and incontinence.
Autonomic symptoms can be the dominant manifestation of a focal seizure, or they can occur as one part of a wider focal or generalised event.
Some are common — particularly seizure-associated heart-rate increases.
Others, such as:
ictal asystole
prominent piloerection
or isolated urinary urge,
are unusual.
And many autonomic seizure symptoms closely resemble non-epileptic disorders.
Palpitations may be cardiac.
Sweating may reflect low blood glucose.
Vomiting may be gastrointestinal.
Breathlessness may be respiratory or anxiety-related.
Collapse may be syncope.
That is why autonomic epilepsy cannot be diagnosed from one bodily sensation alone.
The strongest clue is often the whole recurring pattern:
what happens first, what follows it, how stereotyped it is, and what objective neurological and physiological recordings show.
A seizure does not always announce itself with a convulsion.
Sometimes the first evidence is simply that one of the body's automatic systems suddenly begins behaving in a very unusual — but repeatedly identical — way.
Related Information Hub pages
Focal, Generalised, Unknown and Unclassified Seizures — Understanding the 2025 ILAE Classification
Auras and Epilepsy — The Seizure Before the Seizure?
Fainting, Heart Problems and Epilepsy Lookalikes
Video Telemetry — Recording Seizures in Hospital
EEG — What It Can and Cannot Tell You About Epilepsy
Nausea and Vomiting During Recovery
Bladder and Bowel Changes Around Seizures
Breathing Changes During Seizures
Ictal Asystole and Seizure-Related Bradycardia
Seizure-Related Changes in Heart Rhythm
Self-Limited Epilepsy with Autonomic Seizures — SeLEAS — planned Syndrome Library article
Sources and further reading
International League Against Epilepsy — Updated Classification of Epileptic Seizures, 2025
Current international classification separating seizure classes from semiology descriptors and formally listing cardiovascular, cutaneous, gastrointestinal, pupillary, respiratory and urinary autonomic phenomena.
Beniczky S and colleagues — Seizure semiology: ILAE glossary of terms and their significance — Epileptic Disorders, 2022
Detailed ILAE review defining autonomic seizure manifestations and examining their possible localising and lateralising value.
Baumgartner C and colleagues — Epidemiology and pathophysiology of autonomic seizures: a systematic review — Clinical Autonomic Research, 2019
Systematic review of cardiovascular, respiratory, gastrointestinal, cutaneous, sexual and urinary manifestations occurring during epileptic seizures.
Eggleston KS and colleagues — Ictal tachycardia: the head-heart connection — Seizure, 2014
Review of seizure-associated heart-rate increases and the evidence supporting autonomic cardiac signals as potential seizure biomarkers.
Micalizzi E and colleagues — Seizures and breathing: lessons from peri-ictal respiratory disturbances — Clinical Neurophysiology, 2025
Current review of ictal central apnoea, hypoventilation, hypoxaemia and post-convulsive respiratory dysfunction, including their relevance to SUDEP research.
Epilepsy and Cardiac Arrhythmias: A State-of-the-Art Review — 2024
Contemporary review examining ictal arrhythmias, syncope, bradycardia, asystole, ECG monitoring, heart–brain channelopathies and current understanding of cardiorespiratory mechanisms relevant to epilepsy.
Localizing value of cutaneous ictal phenomena: A systematic review — Epileptic Disorders, 2026
Recent systematic review of piloerection, sweating, pallor and flushing during focal seizures and their potential value as supporting localisation clues.
International League Against Epilepsy — Classification and definition of epilepsy syndromes with onset in childhood, 2022
Current syndrome definition of Self-Limited Epilepsy with Autonomic Seizures, including prominent nausea, retching, vomiting, pallor, flushing and cardiorespiratory symptoms.
Information reviewed: September 2026.
This page provides general educational information for an international audience. Autonomic symptoms can result from epilepsy, cardiac disease, fainting, metabolic disorders, gastrointestinal illness, panic and many other conditions. New unexplained loss of consciousness, significant heart-rhythm disturbance, prolonged breathing difficulty or other severe autonomic symptoms require appropriate medical assessment. Emergency pathways vary between countries.
