Ehlers-Danlos syndrome (EDS) does not directly cause epileptic seizures, but it creates several conditions that can trigger seizure-like episodes or, less commonly, true seizures. Many people with EDS experience convulsive events that look exactly like epileptic seizures, complete with loss of consciousness, shaking, incontinence, and post-event confusion, but stem from entirely different mechanisms. Understanding the distinction matters because these events require different treatments.
Convulsive Syncope: The Most Common Culprit
The most frequent “seizure” in EDS is actually convulsive syncope, a fainting episode that includes involuntary jerking or shaking. When blood pressure drops suddenly or the heart pauses, the brain loses oxygen. If that oxygen deprivation lasts long enough, the brain responds with convulsive activity that can be nearly indistinguishable from an epileptic seizure.
People with EDS are especially prone to this because autonomic nervous system dysfunction is common in the condition. The autonomic system controls heart rate and blood pressure, and when it malfunctions, it can produce sudden episodes of profound low blood pressure and slow heart rate. The resulting brain oxygen loss triggers the convulsions. These episodes can include urinary or even fecal incontinence, eyes rolling back, collapse with injury, and a prolonged period of confusion and exhaustion afterward. In documented clinical cases, some patients experienced post-event confusion lasting 10 to 20 minutes followed by fatigue that persisted for the rest of the day. Without specialized monitoring, these events are routinely misdiagnosed as epilepsy.
One key difference: convulsive syncope often has a brief warning phase. Ringing in the ears, sudden pallor, lightheadedness, or a sensation of warmth may precede the collapse by a few seconds. Epileptic seizures, particularly generalized ones, tend to strike without that kind of prodrome. But the overlap is significant enough that some patients require implantable heart monitors to record what the heart is doing during the actual event before doctors can tell the two apart. In cases where cardiac monitoring revealed prolonged heart pauses (asystole) during convulsive episodes, pacemaker placement completely eliminated the events, confirming they were never epileptic in origin.
How POTS Triggers Seizure-Like Events
Postural orthostatic tachycardia syndrome (POTS) is one of the most common comorbidities in hypermobile EDS, and it provides a direct pathway to convulsive episodes. POTS causes the heart to race abnormally when you stand up, often paired with inadequate blood flow to the brain. Symptoms include lightheadedness, fatigue, sweating, tremor, palpitations, and fainting.
When someone with POTS faints and remains upright, perhaps caught in a chair or held up by a bystander, recovery of blood flow to the brain is delayed. That extended period of reduced brain perfusion can trigger what’s called an anoxic convulsive seizure. The convulsions look identical to epilepsy but are driven entirely by oxygen deprivation rather than abnormal electrical activity in the brain. Medical guidelines are explicit that these events should not be classified as epileptic, even though they involve real, visible convulsions.
Craniocervical Instability and Brainstem Effects
EDS weakens connective tissue throughout the body, including the ligaments that stabilize where the skull meets the spine. This can lead to craniocervical instability (CCI) or atlantoaxial instability (AAI), conditions where the upper neck joints shift more than they should. That excess movement compresses or stretches the brainstem, cranial nerves, and vertebral arteries.
The consequences are wide-ranging: autonomic dysregulation, dizziness, balance problems, sleep apnea, motor weakness, and sensory changes. The autonomic dysfunction caused by this mechanical irritation of the brainstem can itself trigger the syncope and convulsive episodes described above. Research on EDS patients with atlantoaxial instability has shown that surgical fusion of the C1 and C2 vertebrae significantly improved syncopal episodes, pre-syncopal symptoms, and autonomic dysfunction. The authors attributed these symptoms to chronic low-grade stretching and deformation of neural tissue, as well as compromised blood flow through the vertebral arteries.
Chiari malformation type I, where part of the brain extends into the spinal canal, occasionally co-occurs with EDS and can independently raise seizure risk. However, this combination appears to be underreported and has mostly been documented in individual case reports rather than large studies.
Functional Seizures and EDS
There is a third category that deserves attention: functional seizures, previously called psychogenic non-epileptic seizures. These are real, involuntary events, not faking, but they arise from the nervous system misfiring in ways that don’t show up on EEG as epileptic activity. They fall under the umbrella of functional neurological disorder (FND).
The overlap between EDS and functional neurological signs is striking. In one study of 24 patients with hypermobile EDS or hypermobility spectrum disorder, 92% showed at least one functional neurological sign on examination, compared to almost none in healthy controls. Separately, when researchers assessed joint hypermobility in patients already diagnosed with functional seizures, 57% tested positive. And reviews of clinical records for FND patients found that roughly 8% carried a formal EDS diagnosis, with 21% having documented joint hypermobility.
The reasons for this overlap aren’t fully understood, but chronic pain, abnormal body signals from lax tissues, and the constant autonomic instability common in EDS likely all play a role. Recognizing functional seizures matters because they don’t respond to anti-epileptic medications. They typically improve with specialized physical therapy and psychological approaches that address how the nervous system processes sensory input.
Getting the Right Diagnosis
If you have EDS and experience episodes that look like seizures, the cause could be convulsive syncope from autonomic dysfunction, POTS-related fainting with secondary convulsions, brainstem effects from craniocervical instability, functional seizures, or, less commonly, actual epilepsy. These require fundamentally different treatments. Anti-seizure medications treat epilepsy. Pacemakers resolve cardiac-driven convulsive syncope. Volume expansion and compression garments help POTS. Surgical stabilization addresses craniocervical instability. Specialized rehabilitation treats functional seizures.
The diagnostic process typically involves an EEG to check for epileptic brain activity, a tilt table test to evaluate autonomic function, cardiac monitoring (sometimes with an implantable loop recorder worn for months), and potentially imaging of the craniocervical junction. A normal EEG during or between events is a strong clue that the episodes aren’t epileptic. If you’re on anti-seizure medication and it isn’t helping, that itself is a signal worth discussing, since it may point toward one of the non-epileptic causes that are so common in EDS.