Neurocardiogenic Syncope: Frequency and Consequences of its Misdiagnosis as Epilepsy

Abstract

Neurocardiogenic (vasovagal/vasodepressor) syncope (NCS) is a reflex mediated loss of consciousness resulting from the failure of the autonomic nervous system to maintain adequate cerebral perfusion pressure. 1,2 Excessive peripheral venous pooling of blood in combination with aberrant responses of mechanoreceptors to compensatory cardiac hypercontractility results in a paradoxical reflex bradycardia and drop in peripheral vascular resistance. 3,4 The consequent cerebral hypoperfusion induces a transient loss of consciousness that is associated with abnormal movements (e.g. myoclonic jerks) in 12-90% of patients. 2,[5][6][7][8][9][10] Despite clinical guidelines that distinguish NCS ABSTRACT: Background: Neurocardiogenic syncope (NCS) can be mistaken as a seizure. We reviewed the frequency and diagnostic consequences of this misdiagnosis. Methods: A retrospective review of outpatient adult epilepsy clinic charts (QEII Health Sciences Centre, Halifax, NS) was conducted to identify NCS patients referred with a provisional diagnosis of seizures. Charts were reviewed in detail with an emphasis on the consequences of misdiagnosis. Results: Of 1506 consecutive referrals to the epilepsy clinic, 194 (12.9%) ultimately had a clinical diagnosis of NCS. Mean age was 38 +/-16 years (mean age of syncopal onset was 28 +/-16 years). Two-thirds of referrals were from primary care physicians (including emergency departments) and 18% from neurologists. Thirty-five percent were prescribed antiepileptic drugs (AEDs) prior to referral with eight patients (4.1%) experiencing hypersensitivity reactions. Three of five women had adverse pregnancy outcomes while taking AEDs. One-third of patients had restrictions placed on their driving privileges while 11 patients (5.7%) had their employment interrupted. Diagnostic modalities used in the work-up included EEG (90%), CT head (51%), and MRI head (15%). Conclusions: NCS is commonly misdiagnosed as epilepsy. Some patients had an incorrect diagnosis for > 10 years. Patients with this misdiagnosis are often excessively investigated, inappropriately treated, and have unnecessary restrictions placed on driving and employment. RÉSUMÉ: Syncope neurocardiogénique : fréquence et conséquences d'un diagnostic erroné d'épilepsie.Contexte : Une syncope neurocardiogénique (SNC) peut être prise à tort pour une crise convulsive. Nous revoyons la fréquence et les conséquences d'un tel diagnostic erroné. Méthodes : Nous avons effectué une révision rétrospective des dossiers de patients de la clinique externe d'épilepsie (QEII Health Sciences Centre, Halifax, NS) afin d'identifier les patients ayant présenté une SNC qui y ont été référés avec un diagnostic provisoire de crise convulsive. Les dossiers ont été révisés en détail, particulièrement en ce qui concerne les conséquences d'un diagnostic erroné. Résultats : On a posé ultérieurement un diagnostic de SNC chez 194 (12,9%) de 1506 patients consécutifs référés à la clinique d'épilepsie. L'âge moyen des patients était de 38 ± 16 ans et l'âge moyen au moment ...

Paroxysmal nonepileptic events in pediatric patients

“…Obtaining a detailed history including provocative factors, pre-and perisyncopal symptoms, and recovery period plays a key role in differentiating syncope from seizure. Important features of the history that contributed to the diagnosis of syncope were the development of syncope with postural changes after prolonged standing or sitting, the presence of diaphoresis, the absence of aura, postictal sleep or loss of consciousness, and a short duration of episodes [21][22][23][24]. Tilt testing provides a simple confirmatory test, although various tilt angles are in use and have different sensitivities/specificities [25].…”

EEG in Suspected Syncope: Do EEGs Ordered by Neurologists Give a Higher Yield?

“…Reducing the number of inappropriate EEGs requested for suspected syncope would lower the risk of misinterpretation of minor, non-significant abnormalities and inappropriate treatment of patients with anti-epileptic medication (such as may have occurred in one of our patients). In one study from a Canadian tertiary adult epilepsy clinic, 13% of patients were misdiagnosed as having epilepsy when they were in fact suffering from neurocardiogenic syncope 11 . Inappropriate treatment was instituted in 35% of cases, leading to hypersensitivity reactions (4.1%) and adverse pregnancy outcomes (5% of females) 11 .…”

“…In one study from a Canadian tertiary adult epilepsy clinic, 13% of patients were misdiagnosed as having epilepsy when they were in fact suffering from neurocardiogenic syncope 11 . Inappropriate treatment was instituted in 35% of cases, leading to hypersensitivity reactions (4.1%) and adverse pregnancy outcomes (5% of females) 11 . Moreover, one third of their patients had unnecessary restrictions placed on driving and employment 11 .…”

“…Inappropriate treatment was instituted in 35% of cases, leading to hypersensitivity reactions (4.1%) and adverse pregnancy outcomes (5% of females) 11 . Moreover, one third of their patients had unnecessary restrictions placed on driving and employment 11 . More appropriate requisitions would also result in significant cost savings ($23 321.87 per year in our institution alone).…”

Diagnostic Accuracy of Neurological Problems in the Emergency Department

“…[5][6][7] These misdiagnoses may have major implications on the medical care provided to patients, as well as impacting on their quality of life. Such errors can also reduce efficiency within the health care system.…”