Syncope toolkit

Other types of blackout and syncope

In this section: 

• Syncope of unknown origin
• Epilepsy and syncope
• ‘Psychogenic’ pseudo-syncope (PPS)
• Rare causes of blackouts
• Non-haemodynamic collapse / Psychogenic Pseudosyncope (PPS) case history
  

Back to top

Syncope of unknown origin

Reported diagnostic rates can vary considerably depending on a number of factors including the setting in which patients were reviewed, the special interests of the clinicians, whether syncope guidelines are followed, and whether patient who fainted sought medical advice.

In a 2002 study reviewing patients in the original Framingham Heart and Offspring studies, a cause for syncope was not identified in 36.6% of patients, although this study included patients who reported fainting but did not seek medical help and were therefore categorised as ‘undiagnosed’.

In another study where European Society of Cardiology Syncope Guidelines were very carefully followed, 2% of patients remained undiagnosed after investigations. In recent analysis of 10 Syncope Units, a no-diagnosis-rate of the order of 10% was reported.

Back to top

Epilepsy and syncope

In comparison with syncope, epilepsy is much rarer, affecting a little under 1% of the UK population.

• Ictal or epileptic asystole – bradycardia and asystole are rare occurrences during partial complex seizures
• Syncopal epileptic seizures – brain hypoxia as a consequence of syncope can trigger epileptic seizures.

Back to top

‘Psychogenic’ pseudo-syncope (PPS)

There are two main types of conversion disorder associated with blackouts:

• Non-epileptic Seizures (NES) – where limb movements are marked. These can be diagnosed using video or EEG monitoring.
• ‘Psychogenic’ Pseudosyncope (PPS) – episodes which resemble syncope and limb movements are minimal. PPS is collapse which is associated with maintained blood pressure and slightly increased heart rate without the impairment of cerebral circulation that occurs in vasovagal syncope (VVS).

Terminology

There is controversy around the terminology used to describe these episodes. Collapses that look like other conditions but are not explained by the same physiological mechanisms have tended to fall under as many labels as there are specialties encountering them. Hence historically within neurology the term ‘non-epileptic seizures’ is favoured, within cardiology ‘psychogenic pseudosyncope’, and within psychiatry ‘conversion disorders’.

The authors favour the terms non-haemodynamic and non-epileptic collapse; we hope this will be considered and recommended in future working groups but recognise that this is not yet accepted practise. Having taken advice on this with our steering committee and especially patient representatives, it was agreed that an accepted label that enables referral to the appropriate treating specialty is the priority meantime, and hence ‘psychogenic’ pseudosyncope (PPS) is used within this document.

Diagnosis

PPS is not just a diagnosis of exclusion, but in fact such episodes can be diagnosed by appropriate history taking, with very frequent episodes being the main feature.

Diagnosis can be made when episodes are monitored by simultaneous video, beat-to-beat blood pressure and ECG recordings on a tilt-table, without hypotension/bradycardia and confirmed by the patient as being a typical attack. Importantly, there is increasing evidence that both VVS and PPS can commonly both occur in the same patient. Thus, the presence of one does not exclude the other, but different treatment approaches may be required for each.

It is important to be clear that these collapses are outside of the patient’s conscious control and are therefore not malingering or attention seeking behaviours.

Management

Timely delivered psychological therapies to provide reassurance and improve functionality are the primary treatment modalities.

Psychotropic medications may need to be considered in patients with comorbid psychiatric disorders. There is limited evidence for therapy efficacy in PPS, however studies in related conversion disorder populations supports use of psychotherapy. Appropriate interventions include improving detection of bodily sensations and stress markers, and especially in PPS the treatment of underlying anxiety, stress or trauma. Working with a practitioner experienced in this area, motivated patients, with sufficient cognitive capacity for self-insight, can be optimistic of becoming PPS episode free.

Back to top

Rare causes of blackouts

Vertebrobasilar TIA – rarely causes syncope and always associated with neurological signs including nystagmus, dysarthria, limb weakness, ataxia, vertigo and diplopia.

Subclavian Steal – this is a rare phenomenon which occurs if blood flow is reversed in the vertebral artery toward the ipsilateral distal subclavian artery by the demand for flow to the exercising arm of the same side. The cause is a narrowing or occlusion of the proximal subclavian artery. The phenomenon is associated with neurological signs.

G-induced loss of consciousness (G-LOC) – this is due to the centrifugal effect of rapid acceleration. Although rare, it is common in aircrew, and was experienced by 15% of RAF crew in 2015, mostly during training. G-LOC has been associated with air crash fatalities.

Back to top