Amnesia for loss of consciousness is common in vasovagal syncope
Europace
Amnesia for loss of consciousness is common in vasovagal syncope
Clodagh O'Dwyer 2
Kathleen Bennett 1
Yvonne Langan 0
Chie Rose Anne Kenny 2
Wei Fan 2
0 Department of Neurophysiology, St. James's Hospital , James' St, Dublin 8 , Ireland
1 Department of Pharmacology and Therapeutics, Trinity Centre for Health Sciences, St James's Hospital , James' St, Dublin 8 , Ireland
2 Falls and Blackout Unit, Department of Medical Gerontology, St James's Hospital , James' St, Dublin 8 , Ireland
Aims The aim of this study was to determine the prevalence of amnesia for loss of consciousness (A-LOC) in those who have a history suggestive of vasovagal syncope (VVS) and who develop syncope on head-up tilt (HUT) table testing. Furthermore, we wished to determine if A-LOC is an age-dependent phenomenon in VVS and whether haemodynamic parameters on tilting can predict for A-LOC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methods Patients were recruited in a dedicated syncope unit and underwent neurocardiovascular evaluation as indicated under and results European Society of Cardiology guidelines to illicit a diagnosis of VVS. A set protocol of questioning occurred following induced syncope to determine the presence of A-LOC. The prevalence of A-LOC following syncope on tilting was 28% (44/159). Forty-two per cent of those ≥ 60 years of age vs. 20% ,60 years of age experienced amnesia post-induced syncope (P ¼ 0.003). However, regression analysis did not show age to be an independent predictor for A-LOC. Blood pressure change between those without amnesia and those with amnesia showed no significant difference (P ¼ 0.687). There was a significant difference in heart rate response; those experiencing amnesia had reduced bradycardic response on HUT compared with those without amnesia (P ¼ 0.001). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion Amnesia for loss of consciousness is common in VVS. Although more prevalent, it is not unique to older age-groups. Absence of syncope associated bradycardia during HUT testing predicts for A-LOC. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Introduction
Amnesia for loss of consciousness (A-LOC) has been commonly
described in the setting of neurological injury such as traumatic
head injury, seizures or in the setting of transient global
amnesia.1 Syncope is defined as a transient spontaneous loss of
consciousness, characterized by a loss of postural tone with a
spontaneous recovery.2 Neurally mediated syncope encompasses
carotid sinus syndrome (CSS) and vasovagal syncope (VVS).
Temporary reduction of cerebral blood flow occurs with syncope,
including to regions which control memory such as the
hippocampus and reticular activating system.3 The relevance of
amnesia in the setting of neurally mediated syncope is important
in the context of unexplained falls particularly in older adults.4,5
If an individual does not recall syncope, an inappropriate pathway
of investigation may ensue and modifiable underlying causes
overlooked. Recurrent episodes increase further the risk of
injury and fracture. In older adults witness account may only be
available in up to 40% of persons with syncope or unexplained
falls.6 A witness account is often the vital key in establishing
whether a definite loss of consciousness has occurred. Without
it, investigating the underlying aetiology of unexplained falls or
drop attacks becomes a much more challenging task.
Thirty per cent of individuals with CSS and witnessed loss of
consciousness have A-LOC during reproduction of symptoms in a
clinical setting.7 A study assessing characteristics of patients presenting
with unexplained falls vs. unexplained syncope reiterated this
point. Ninety-five percent of those presenting with unexplained
falls had A-LOC during carotid sinus massage compared with 27%
of those with syncope as a presenting symptom.8 This exposes the
dilemma which exists when assessing an older faller who presents
with both lack of warning and lack of witness account for events.
Vasovagal syncope is often referred to as a more benign form of
neurally media (...truncated)