Final diagnosis: faint or seizure?

Making the right definitive diagnosis of transient lack of consciousness generally is a challenge for even essentially the most experienced clinician. Syncope and seizures rank high on the differential diagnosis list, followed by narcolepsy, cataplexy, pseudoseizures, and pseudosyncope (Sheldon, 2015). Differentiating between these two major candidates will be difficult, and investigation is commonly equivocal or incorrect.

What is the difference between fainting and seizures?

Studies suggest that 20-40% of patients diagnosed with epilepsy are misdiagnosed, and syncope is essentially the most common misdiagnosis in epilepsy (Hackethal, 2017). Let’s take a more in-depth have a look at this medical enigma of diagnosis.

Symptoms and causes of fainting

Syncope is defined as a symptom that presents with a sudden, transient, complete lack of consciousness related to an inability to keep up postural tone, with a rapid and spontaneous recovery, and that’s attributable to cerebral ischemia. Studies of syncope report prevalence rates as high as 41%, with recurrent syncope occurring in 13.5%, and the prevalence of syncope as a symptom presented to the emergency department has ranged from 0.8% to 2.4% (Shen et al., 2017). The most typical causes of syncope include reflex syncope (blood exposure/trauma), orthostatic syncope, cardiac arrhythmias, and structural cardiopulmonary disease (Benditt, 2024). Often, syncope is preceded by a prodromal or presyncopal period that will include a constellation of symptoms including dizziness, feeling hot or cold, profuse sweating, palpitations, nausea/abdominal discomfort, blurred vision, pallor, or hearing changes (Benditt, 2024).

Symptoms and causes of epileptic seizures

Epileptic seizures are divided into two categories: epileptic and nonepileptic.

They occur spontaneously or unprovoked and are recurrent. They are further classified as generalized tonic-clonic seizures and the more common, complex partial seizures (Sheldon, 2015). Causes of seizures include brain injury, stroke, brain tumors, and neurological disorders. Diagnosis is made based on abnormal brain activity on an electroencephalogram (EEG).

causes may include fever, infection, electrolyte imbalance, drug/alcohol withdrawal, psychiatric conditions, and hypoglycemia. A patient having a non-epileptic seizure can be expected to have normal brain wave activity on EEG.

What is convulsive syncope?

Many cases of syncope involve lack of consciousness because the only symptom. A diagnostic problem arises when the patient with syncope also has myoclonus or seizures. These events are sometimes known as seizure-like syncope or convulsive syncope. Myoclonus and tonic spasms are essentially the most confusing signs within the differential diagnosis between syncope and seizures (Bergfeldt, 2003). The basic pathophysiology of convulsive syncope is as follows: cardiac syncope causes a variable amount of hemodynamic instability, leading to cerebral hypoperfusion, which triggers spinal reticular formation and ends in myoclonic activity that mimics convulsive activity (Patel and Cohen, 2013).

Diagnosing fainting and seizures

The gold standard for distinguishing between the 2 can be video telemetry with simultaneous EEG and electrocardiographic (ECG) recording using electrodes on the pinnacle and chest – a clinical scenario that is never met (Bergfeldt, 2003). One of crucial clues often comes from an attentive bystander who witnesses the event and is capable of report whether the person went limp after which convulsed (fainted) or whether the episode began with convulsions (seizure). Be alert for other clues as well.

Syncope is related to identifiable triggers, and seizures are inclined to be longer in duration than syncope and are followed by postictal confusion and significant fatigue, although temporary periods of confusion have been reported in convulsive syncope. Other typical features of convulsive syncope that aren’t common in seizures include a period of presyncope with prodromal features, pallor, duration lower than one minute, and constant or upward deviation of the eyes. On the opposite hand, typical seizure features that aren’t common in syncope may include tongue biting, prodromal cry, urinary incontinence, duration often several minutes, and lateral deviation of the eyes (Sheldon, 2015). Accurate diagnosis is commonly challenged by the patient’s amnesia concerning the events, lack of witnessing/reporting, and disagreement amongst physicians (McKeon, Vaughan, & Delanty, 2006).

Evaluation of patients for seizures and syncope

The evaluation of a patient who presents with a transient lack of consciousness could also be extensive and sometimes includes cardiology and neurology consultations. All patients will need to have a comprehensive history and physical examination.

• Detailed medical history
• Number, frequency and duration of episodes
• Time of occurrence
• Body position on the time of the incident
• Provoking aspects or accompanying symptoms preceding the event
• Symptoms after the event
• Witness report, if available
• Medicines
• Family history

• Measurements of heart rate and blood pressure with the patient lying, sitting and standing to evaluate orthostatic hypotension
• Blood pressure in each arms; unevenness indicates aortic dissection or stenosis
• Respiratory rate to evaluate hyperventilation as seen in pulmonary and/or psychiatric causes
• Carefully auscultate heart sounds to evaluate for heart murmurs
• Consider Cautious Carotid Artery Massage within the Elderly Patient
• Neurological examination

Recommended tests

Initial evaluation must also include an ECG, echocardiogram, and basic laboratory tests to rule out anemia, infection, electrolyte imbalance, or renal and hepatic dysfunction.

The ECG is a robust tool within the evaluation of a patient with a transient lack of consciousness. The ECG might help evaluate for arrhythmias (sinus bradycardia, sinus pauses, atrioventricular blocks, ventricular tachycardia, bundle branch blocks), intraventricular conduction delays, preexcited QRS complexes, left ventricular hypertrophy, and pacemaker or implantable cardioverter-defibrillator malfunction, amongst others.

Echocardiogram assesses structural heart disease, including left ventricular dysfunction, hypertrophic cardiomyopathy, significant aortic stenosis, intracardiac masses, and right ventricular enlargement (suggestive of pulmonary embolism). This initial assessment provides a comparatively confident diagnosis in about 50% of cases (Benditt, 2024).

Based on the outcomes of the initial examination, further testing could also be warranted depending on the findings and clinical suspicion. When the suspicion of epilepsy is high with a primary unprovoked seizure or focal neurological deficits, half-hour of interictal EEG and neuroimaging, including CT or MRI.

Ambulatory ECG monitoring is warranted when there’s a suspicion that a cardiac arrhythmia will be the reason behind syncope. There are three options for ECG monitoring, including continuous ambulatory ECG (Holter) and patch monitoring, event monitoring and mobile cardiac telemetry monitoring (MCOT), and implantable cardiac monitors. While exercise testing tends to have poor diagnostic yield in patients with syncope, it could be helpful in those that develop symptoms with maximal exertion. Tilt testing is controversial and is mostly not performed (Benditt, 2024).

Carotid sinus massage could also be considered to detect carotid sinus syndrome, which primarily affects men over 60 years of age or patients with previous head and neck surgery. It must be performed by an experienced clinician and will not be really helpful in patients with a history of transient ischemic attack or stroke inside the last three months or in patients with a neck bruit (Benditt, 2024).

When a patient presents with a transient lack of consciousness, arriving at an accurate diagnosis will be daunting. However, it’s a doable task, first by documenting a superb history and physical examination, then by performing the above standard tests, and eventually by collaborating with colleagues in cardiology and neurology.

Fainting vs. Seizure References

Benditt, D. (2024). Syncope in adults: clinical features and initial diagnostic evaluation. www.uptodate.com/contents/syncope-in-adults-clinical-manifestations-and-diagnostic-evaluation

Benditt, D. (2024). Syncope in adults: risk assessment and extra diagnostic evaluation. www.uptodate.com/contents/syncope-in-adults-risk-assessment-and-additional-diagnostic-evaluation

Bergfeldt L. (2003). Differential diagnosis of cardiogenic syncope and paroxysmal disorders. , (3), 353–358. https://doi.org/10.1136/heart.89.3.353

Hackethal, V. (2017). Epilepsy, syncope, or each?https://www.neurologylive.com/view/epilepsy-syncope-or-both

McKeon, A., Vaughan, C., & Delanty, N. (2006). Seizures and syncope. , (2), 171–180. https://doi.org/10.1016/S1474-4422(06)70350-7

Patel, DP, and Cohen, TJ (2013). Cardiac syncope versus epileptic seizure: the worth of EP consultation. (2). https://www.hmpgloballearningnetwork.com/site/eplab/feature-story/cardiac-syncope-versus-seizure-value-ep-consult

Sheldon R. (2015). How to differentiate syncope from a seizure. , (3), 377–385. https://doi.org/10.1016/j.ccl.2015.04.006

Shen, W. K., Sheldon, R. S., Benditt, D. G., Cohen, M. I., Forman, D. E., Goldberger, Z. D., Grubb, B. P., Hamdan, M. H., Krahn, A. D., Link, M. S., Olshansky, B., Raj, S. R., Sandhu, R. K., Sorajja, D., Sun, B. C., and Yancy, C. W. (2017). 2017 ACC/AHA/HRS Guidelines for the Evaluation and Treatment of Patients with Syncope: Report of the American College of Cardiology/American Heart Association and Heart Rhythm Society Clinical Practice Guidelines Task Force. , (5), e60–e122. https://doi.org/10.1161/CIR.0000000000000499