It is clear from referral patterns and current care pathways that many doctors assume that T‐LOC is usually caused by epilepsy, but in fact syncope is more likely1,2,3
(table 1). The majority are cases of reflex syncope, with up to 50% of people suffering reflex syncope during their lives. In most patients this presents as simple fainting, and many sufferers never come to neurological evaluation. However, a very significant number of patients with syncope may be misdiagnosed with epilepsy. This is a common mistake, it damages patients lives, may result in failure to respond to treatment, and may be very dangerous. For example, in the UK only about 4% of patients attending neurological clinics have an ECG recorded (http://www.nice.org.uk/pdf/CG020fullguideline.pdf
). Cases of T‐LOC caused by transient polymorphic ventricular tachycardia (VT) in the congenital long QT syndrome have been misdiagnosed as epilepsy. This has previously led to cardiac arrest and hypoxic brain damage in young people, after wrong treatment with antiepilepsy drugs (author's experience). The STARS Medical Advisory Committee (STARS MAC, www.stars.org.uk
), with European and North American multidisciplinary membership comprising cardiologists, paediatric and adult neurologists and general physicians, agree that this is a worldwide problem. Furthermore, close collaboration between neurologists and cardiologists is now advocated by the National Institute for Health and Clinical Excellence (NICE) guidelines (http://www.nice.org.uk/pdf/CG020fullguideline.pdf
), although generally such collaboration still seems to be unusual.
Table 1Causes of blackout presenting to primary care or emergency departments
Current understanding puts the prevalence of epilepsy at 0.5–1%.4
Syncope is thought to be more common than epilepsy, affecting 15% of children under the age of 18 years and a similar percentage of middle aged men and women.5
The prevalence rises significantly in the elderly population, with approximately a quarter of all patients over 70 years of age experiencing an attack, of which one third will have a recurrent blackout in the next two years.5
A number of studies, including our own,6
have shown that between 20–30% of patients diagnosed as suffering from epilepsy do not actually have this disorder.7w1 w2
Others put misdiagnosis rates as high as 40%, in children.w3
Zaidi and colleagues6
investigated 74 patients (mean (SD) age of 38.9 (18) years, range 18–77 years) diagnosed with epilepsy, half of them continuing to have seizures despite medication, by means of a head up tilt test and carotid sinus massage during continuous electrocardiographic, electroencephalographic, and blood pressure monitoring. In addition, 10 patients also underwent long term ECG monitoring with an implantable loop recorder. An alternative diagnosis was found in 31 (41.9%) patients including 13 (36.1%) of those taking an anticonvulsant. Eleven of 13 patients (84.6%) who were taking medication could successfully stop this because of an alternative diagnosis being established.
Blackouts or T‐LOC are common—some patients clearly have fainting episodes or syncope caused by an evident arrhythmia, and some patients clearly have epilepsy. However, the common experience of a misdiagnosis of epilepsy indicates that many doctors equate blackouts/T‐LOC with epilepsy and should give syncope much greater consideration, and also indicates that there are a great many patients in whom the cause of T‐LOC is far from clear. These patients are in a “grey area” diagnostically between clear fainting and clear epilepsy. This article aims to explore the reasons why this is so, and examine the value of clinical skills and objective testing in T‐LOC, as well as looking at therapeutic options when a diagnosis is made.