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By Lucy Piper, Senior medwireNews Reporter

Psychogenic pseudosyncope (PPS) may be going undetected in some patients because it coincides with vasovagal syncope (VVS), researchers report in Neurology.

Roland Thijs (Stichting Epilepsie Instellingen Nederland, Heemstede, the Netherlands) and colleagues found that the two conditions co-existed more often than expected. Among 1164 single tilt-table tests carried out, VVS coincided with PPS in 23 (2%) patients, which was 16 more than would be expected by chance.

In 83% of cases, PPS immediately followed VVS despite the patients’ heart rate, blood pressure and electroencephalogram (ECG) readings returning to normal, while in the remaining 17% of cases, PPS occurred immediately or several minutes before the onset of VVS.

In a related editorial, Selim Benbadis (University of South Florida, Tampa, USA) and Richard Sutton (Imperial College, London, UK) point out the important practical implications of the findings: “Internists and cardiologists who evaluate syncope should consider the diagnosis of PPS more often and earlier”.

To help in this, Thijs and team were able to identify “a complex phenotype” in VVS/PPS patients when compared with 69 individuals with VVS alone.

The patients with co-existing PPS experienced attacks significantly more frequently, at two per month versus 0.25 per month. They were also 2.86 times more likely to lose consciousness for more than a minute and 8.14 times more likely to experience a delay in recovery of consciousness. During an attack, patients with VVS/PPS were 3.75 times more likely to close their eyes than VVS patients.

All the patients reported prodromes and triggers typical of VVS, but the patients with co-existing PPS were 5.57-fold more likely to experience episodes without prodromes and fivefold more likely to experience episodes with atypical triggers.

The editorialists say that the findings illustrate the provocative ability of tilt-table tests, pointing out that “[i]f a standing provocation test were performed on all patients with syncope unexplained by history, physical, and 12-lead ECG, a notable and larger proportion with PPS might be found and coincidence with VVS may be less.”

Thijs and colleagues make the point, however, that diagnosis of PPS should be based on the examination of features in as many attacks as possible, as single tilt-table results indicating isolated VVS or no transient loss of consciousness do not necessarily exclude the occurrence of VVS/PPS in everyday life. This is also why the 2% VVS/PPS rate identified in the study as a result of single tilt-table tests is likely to be an underestimation.

“In our experience, VVS/PPS is a common scenario among those with chronic and apparent refractory syncope”, they conclude.

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