Psychogenic pseudosyncope is apparent loss of consciousness without any change in cerebral perfusion or in the electroencephalogram. On tilt testing the diagnostic pattern is an attack occurring with normal blood pressure, normal heart rate and a normal waking electroencephalogram, which excludes both syncope and seizure. The semiology described here is characteristic: high attack frequency, long duration, eyes closed with resistance to passive opening and eyelid fluttering, absence of injury and immediate complete recovery.
Duration and eye behaviour are the most useful clinical discriminators. True syncope is brief, usually under 30 seconds, with the eyes open and often a few myoclonic jerks; epileptic seizures are also usually short, with the eyes open, and are followed by postictal confusion. Prolonged motionless unresponsiveness with closed eyes for many minutes is highly suggestive of a dissociative mechanism. Systematic study of tilt-induced pseudosyncope confirms these features and also notes that patients frequently have a normal or slightly elevated heart rate during the event rather than the bradycardia of vasovagal syncope.
This is solid PGY-3 and PGY-4 knowledge of episodic disorders, placing the item at the Intermediate level of RITE content. Remember that pseudosyncope and true syncope can coexist in the same patient, so a positive tilt study showing hypotension does not exclude additional functional attacks.
Incorrect Answers
- A. Vasovagal syncope on tilt testing is defined by a fall in blood pressure with or without bradycardia at the time of symptoms; both were normal here.
- B. Focal impaired awareness seizures show ictal electroencephalographic change, are usually under two minutes, and are followed by postictal confusion.
- C. Autonomic failure produces a sustained fall in blood pressure on tilt without an adequate compensatory heart rate rise.
- E. Postural orthostatic tachycardia syndrome requires a sustained heart rate increase of at least 30 beats per minute on standing, which did not occur.
Testing Pearls
- Pseudosyncope on tilt shows an attack with normal blood pressure, heart rate and electroencephalogram.
- Prolonged motionless unresponsiveness with closed eyes strongly favours a dissociative cause.
- Resistance to passive eye opening is a useful positive bedside sign.
- True syncope is brief, occurs with the eyes open and may include a few myoclonic jerks.
- Pseudosyncope and genuine syncope can coexist in the same patient.
References
- Jankovic J, Mazziotta JC, Newman NJ, Pomeroy SL, editors. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022. p. 2079.
- Tannemaat MR, van Niekerk J, Reijntjes RH, Thijs RD, Sutton R, van Dijk JG. The semiology of tilt-induced psychogenic pseudosyncope. Neurology. 2013;81(8):752-758.
- Avbersek A, Sisodiya S. Does the primary literature provide support for clinical signs used to distinguish psychogenic nonepileptic seizures from epileptic seizures? J Neurol Neurosurg Psychiatry. 2010;81(7):719-725.
