Can POTS Cause Seizures? Convulsive Syncope vs a Seizure

Our team sees the fast heart rate in POTS as a rescue for brain blood flow. In the clinic's words, a rising heart rate is "the way that your brain and body prevent you from passing out," so "it's rescuing you in a way." A faint means that rescue has failed: in our team's view, blood pressure has fallen far enough to starve the brain of blood flow.

That's why the clinic says you can't faint from POTS itself. POTS is the compensation succeeding, and orthostatic hypotension is the same compensation failing. The Heart Rhythm Society's consensus statement describes it from the patient's side: "many patients with POTS faint occasionally, although presyncope is much more common" (Sheldon, 2015). Both statements hold, because people diagnosed with POTS do faint, and our team reads each faint as the moment blood pressure or brain blood flow lost the fight.

In one group of 40 patients who met POTS criteria on a tilt test, 77.5% reported loss of consciousness, and 45% also had neurocardiogenic syncope (Chouksey, 2021). That was a small group referred for symptoms, so it doesn't give a rate for everyone with POTS. Why the faint itself happens is covered in can you faint from POTS.

What Is Convulsive Syncope (Jerking When You Faint)?

Convulsive syncope is a faint followed by muscle jerks. In our team's description, "it's passing out and then having spasms," usually myoclonic jerks, and "sometimes people will kind of vocalize or hallucinate in those moments as well." What sets it apart from a typical seizure, in the clinic's words, is that "we don't see the epileptiform waves on the EEG."

Jerking is common when people faint. A video-EEG study compared 65 faints brought on by a tilt test with 50 convulsive seizures in people aged 15 and older, and found that "jerks and tonic postures were common in syncope, but semiology differed from convulsive seizures" (Shmuely, 2018). Most of the jerks came during the slow-wave phase of the EEG, and in any faint the EEG changes reflect low blood flow to the brain (Brenner, 1997).

Spells like these are sometimes treated as epilepsy first. In 15 people whose seizure-like episodes hadn't responded to antiseizure drugs, a tilt test brought on a faint with seizure-like movements in 67%, and the EEG during the episode showed diffuse slowing, unlike a typical epileptic seizure (Grubb, 1991). Among 19 children and young adults aged 5 to 20 tested with tilt and video-EEG together, 8 fainted during the test, and three-fourths of those with syncope had first been diagnosed with epilepsy and given antiepileptic drugs (Yilmaz, 2012).

Antiseizure drugs help epilepsy. In the clinic's view, their ceiling is a spell that starts with low blood flow to the brain, which fits the spells in Grubb's group that hadn't responded to them. Medication decisions belong with your prescribing doctor.

1. Faint: blood pressure and brain blood flow fall, the EEG slows and briefly goes flat, a couple of jerks come in the slow phase, the body goes limp, and recovery is quick once the person is lying flat.
2. Seizure: the EEG shows epileptiform activity, the body keeps its tone, and the jerks run into the dozens.
3. Under 10 jerks favors a faint and over 20 favors a convulsive seizure, the "10/20 rule" from one video-EEG study.

Seizure or Faint: How Can You Tell the Difference?

Seizures and faints share enough clinical features to cause "diagnostic confusion," even though the processes behind them are distinct (Britton, 2004). In the Shmuely video-EEG study, what the body did during the episode differed in measurable ways.

Jerks, tone and syncope EEG from Shmuely, 2018 (65 tilt-induced faints, 50 convulsive seizures). Seizure EEG as the clinic describes it. Recovery from the Heart Rhythm Society definition of syncope (Sheldon, 2015).

What Is the 10/20 Rule?

The Shmuely study proposed a simple count: "less than 10 indicates syncope and more than 20 a convulsive seizure," which the authors called the "10/20 rule." It also found that "loss of tone strongly favors syncope" (Shmuely, 2018). Between 10 and 20 jerks, the count doesn't point either way. The rule comes from that one cohort, so it adds to the history and testing rather than settling a diagnosis.

What Do EEG, ECG and Tilt Testing Show?

The Heart Rhythm Society lists "differentiating convulsive syncope from true seizure activity" among the uses of tilt-table testing (Sheldon, 2015). Yilmaz's group found that synchronous tilt testing and video-EEG "give more information than doing them separately" (Yilmaz, 2012).

An EEG recorded during a faint can't settle the question alone. Whether the faint comes from a vasovagal reflex, a heart rhythm problem, an epileptic seizure or low blood pressure, the EEG findings "are similar and reflect cerebral hypoperfusion" (Brenner, 1997).

The heart needs checking too. In 376 people sent for EEG because of suspected epilepsy, a single ECG channel recorded alongside it showed abnormalities in 68 (18%), and the authors concluded that "arrhythmia is not uncommon in the etiology of syncope which mimics epilepsy" (Kendirli, 2015). That was a retrospective review with one ECG channel.

When people come in with spells like these, our team wants to "look very very hard at what blood pressure looks like and specifically what does blood flow to the brain look like." What the test involves, including passing out during one, is in the tilt table test guide.

Can You Have Epilepsy and Fainting at the Same Time?

Seizures and syncope "may coexist in the same patient," and a seizure can itself be complicated by a heart rhythm problem and a faint (Britton, 2006). In a prospective study of 107 patients at epilepsy centres with possible or drug-resistant epilepsy, the final diagnosis was syncope alone in 42.1%, epilepsy alone in 19.6% and both in 37.4% (Ungar, 2017). Those patients were epilepsy-clinic referrals without a POTS diagnosis, so the figures don't transfer to POTS. They do show why a faint with jerks deserves a look at both the brain's electrical activity and its blood flow.

Is It Vasovagal Syncope or POTS?

It can be both. The Heart Rhythm Society notes that vasovagal syncope and POTS "are not mutually exclusive" (Sheldon, 2015). Vasovagal syncope comes in 3 types on a tilt test, in our team's description. In the cardioinhibitory type, "the heart rate starts to drop" until blood flow can't be maintained. In the vasodepressor type the blood pressure drops until people pass out, and in the mixed type both fall. In the clinic's view there also "appears to be a neurogenic component," because some work shows the faint can come before blood pressure or heart rate reaches a threshold.

The timing on a tilt test differs by type. Vasovagal syncope shows blood pressure falling after more than 3 minutes upright and the heart rate falling later, while classic orthostatic hypotension shows an immediate, progressive fall in blood pressure with little change in heart rate (Cooper, 2023).

Dehydration adds to the risk: in our team's words, people who are dehydrated are "more likely to faint." Low blood volume has its own page on hypovolemic POTS.

What Are Pseudo-Seizures (PNES)?

A pseudo-seizure, in our team's description, is an episode where "when you measure them with the EEG even during the seizure episode we don't see evidence of increased brain activity for epileptiform activity." When someone passes out with convulsive movements and no epileptiform activity, they "kind of get bucketed" into this category, and the common term now is PNES, psychogenic non-epileptic seizures.

In the clinic's view, the label leaves the cause open. Our team sees cerebral hypoperfusion as "a common one" behind these episodes and warns that "if we kind of dismiss people and tell them that it's all in your head then we steal the ability to tackle it." That's why our chiropractic neurologists check blood pressure and brain blood flow before accepting the label. In the clinic's view, a faint should be ruled out before an episode is called PNES. The wider plan is in POTS treatment, and how functional disorders overlap with fainting is covered in FND and fainting.

When Should You Go to the ER or See a Neurologist?

• Call emergency services for a first seizure, an injury, or when the person doesn't recover quickly. This is general safety guidance, not a clinic position. A faint by definition comes with "rapid and spontaneous recovery" (Sheldon, 2015), so an episode without quick recovery is a reason to call.
• Ask a doctor promptly about an unexplained faint. A 2026 review found that emergency department patients with syncope "are mostly high-risk according to ESC criteria and not suitable for direct discharge from ED" (Mockel, 2026).
• Ask for a heart workup when a faint has features of a heart rhythm problem. A review of drop attacks sets out clinical and electrographic criteria that "suggest underlying arrhythmia or other serious cardiac disorders that require further investigation" (Manford, 2024).
• Ask a neurologist about any first spell, spells with more than 20 jerks, or spells where the body stays stiff, ideally with tilt and video-EEG recorded together (Shmuely, 2018; Yilmaz, 2012).

None of the sources behind this article sets a seizure length at which to call for help, so ask your neurologist what length should trigger a call in your case.

Where Do You Start If Your Spells Were Called Seizures?

Start by measuring what happens to your blood pressure and brain blood flow when you stand, since that's where a faint with jerks begins.

POTS and Seizures FAQ

Dr. Keiser is a board-certified chiropractic neurologist (DC, DACNB, FABBIR), not a medical doctor (MD/DO). This content is for educational purposes and does not constitute medical advice. It is not a substitute for professional medical evaluation, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. Medication decisions should be made with your prescribing physician.

← Back to Blog