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Abstract
The differential diagnosis of episodes of transient loss of consciousness can be straightforward but can also present some of the greatest diagnostic difficulties. In most circumstances, when there is uncertainty, usually when there have been only one or a few poorly observed events, it may be reasonable to admit to that uncertainty and await any further events to clarify the diagnosis. We have reason to know from bitter experience that this is not always the case and that more rigorous consideration of investigation may be justified rather than allowing the passage of time to clarify the diagnosis.
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Introduction
Clinicians learn more from their mistakes than from any successes they might enjoy. This paper is intended to pass on the lessons learned from one such mistake.
Case report
Nina is seen in figure 1, aged 23 in 2005 on her graduation in architecture from Liverpool University. She was very proud to have studied at Liverpool. Her grandfather had studied medicine there and one of us (PJ, her mother) was born at the Maternity Hospital. Nina was a healthy, happy and well adjusted young woman. She had suffered no illnesses in her life and was athletic, swimming and playing soccer for her high school team in the USA where she lived for several years. She enjoyed squash at university and was a talented graphic artist (figure 2). Two weeks later she was dead.
Nina Jelen.
Nina's sketch of buildings in Prague.
History
At the age of 21 she had woken her boyfriend in the early hours one morning when they were both sleeping. Her breathing was erratic, her body stiff, her eyes open and she was unresponsive for 2–3 min. She did not have tonic or clonic movements, tongue biting or incontinence. She was drowsy and amnesic for the event. She was taken to an accident and emergency (A&E) department where she was found to be a fit healthy young woman and an ECG was thought to be unremarkable (figure 3). Onward referral was made to the local first seizure clinic.
ECG recorded at first presentation to the accident and emergency department.
She was seen in clinic approximately 4 weeks later, by DC. There had been no further symptoms and no relevant history could be added. There was clinical uncertainty about the nature of the attack but it was felt most likely that an event arising from sleep could be a seizure. A standard EEG (figure 4) and an MR brain scan were both reported as normal.
Normal EEG recording with single channel of ECG.
She was seen again following the results. It was felt that no definite diagnosis could be made but that Nina should be seen again if she were to experience a recurrence. There was none before she was found at home dead, in bed.
Following Nina's death her three brothers had cardiac investigations on the advice of a family friend, a cardiologist who considered that a channelopathy might provide an explanation. Her older brother was investigated in the USA where the cardiologist asked for a copy of the ECG taken when Nina had her first episode (figure 3). A diagnosis of long QT3 was made and subsequently confirmed by a cardiac electrophysiologist who wrote that:
“It is difficult to interpret the A&E ECG and the machine has miscalculated QT and QTc, but there is undoubted QT prolongation. Some QT intervals are almost 600 ms.”
At this stage, the single channel of ECG recorded in her standard EEG was reviewed (figure 4). The QT interval and corrected QT interval (QTc) can be calculated from a formula (figure 5), which although not without some controversy, is a simple method:
ECG QRS complex and QT interval.
where RR is heart rate in beats per min. QT on her ECG recorded with her EEG can be measured as 530 ms, which with a heart rate of 50 beats/min leads to a QTc of 523 ms, exceeding the usually accepted upper limit of normal of 430 ms. It was tragic that her EEG was recorded 2 months before the EEG department started an audit of the routine measurement and reporting of QT and QTc intervals.
Discussion
Congenital long QT syndromes are a group of cardiac channelopathies characterised by delayed repolarisation of the myocardium, QT prolongation and increased risk for syncope, and sudden cardiac death in the setting of a structurally normal heart in an otherwise healthy individual.1 Up to 100 genetic polymorphisms causing abnormality in the myocardial sodium channel have been identified. A number of eponymous syndromes have been described including Romano–Ward and Lange–Nielson syndromes. The channelopathies are a genetically heterogeneous disorder most often inherited as autosomal dominant.
Chanelopathies are thought to affect some 1 in 3000 individuals and to cause 15% of sudden infant deaths and up to 30% of unexplained sudden deaths in adults less than 40 years old. Untreated, channelopathies have approximately a 1% per annum risk of fatal arrhythmia. In about 5% of the total population of those with channelopathies it is thought that a fatal arrhythmia is the first presentation of the condition. The investigation and treatment of long QT syndromes is the preserve of tertiary electrophysiological cardiology. It is important to determine the type of syndrome, particularly with respect to the safety of β blockers. The mainstay of treatment is now an implantable cardiac defibrillator.
The lessons
In the great majority of people, differentiation between seizures and syncope is straightforward although all neurologists must be aware that positive motor phenomena can occur during syncope2 and the diagnostic difficulty that this can cause. However, cardiac causes of transient loss of consciousness can be misdiagnosed as epilepsy.3 Increasing age and the presence of a vascular history and risk factors will always be helpful in identifying patients with cardiogenic syncope. Although in younger people, reflex neurogenic syncope and epilepsy are much more common causes of blackouts than the rare inherited channelopathies, clinicians need to be aware of both their clinical features and ECG characteristics. Unfortunately, a significant proportion of even cardiologists, as well as neurologists, may miss the diagnosis, and automated reporting of QT intervals can be misleading, as in Nina's case.4
In the channelopathies, episodes of transient loss of consciousness are often provoked by factors such as exercise, anxiety and startle. They can also occur in sleep as in Nina's case. ECG abnormalities should always raise the index of suspicion, including unexpected bradycardia (box 1).
Box 1 Electrocardiographic and clinical features of long QT syndrome
So how can we prevent more people dying in tragic circumstances similar to those of Nina's death?
The UK National Institute for Health and Clinical Excellence (NICE) guidelines for epilepsy draw attention to the need for standard ECG recordings in all subjects with a diagnosis of epilepsy or suspected epilepsy (http://www.nice.org.uk/download.aspx?o=CG020NICEguideline). Neurologists should adhere to this.
Neurologists should be familiar with guidelines on the investigation of syncope.5
Neurophysiology departments should ensure that EEGs also record a channel of ECG in which QT and QTc are reported.
Neurologists should be aware that standard automated reporting of QT interval on modern ECG equipment can be erroneous. Where there is any diagnostic doubt, expert cardiological opinion should be sought.
We need to ensure that there are local arrangements for joint working between neurologists and cardiologists for optimal management of patients presenting with transient loss of consciousness.
There will shortly be NICE clinical guidelines published for the management of transient loss of consciousness. Neurologists, cardiologists and other relevant specialists should read these and incorporate the recommendations into their everyday practice.
Medicine is a high risk profession and the stakes can be very high for our patients. Errors and omissions are more likely in rare conditions and when presentations and investigations do not immediately point to a diagnosis. They should always form a learning point to be passed on. It is essential that clinicians are open and honest about the mistakes they make.6 Neurologists, as a specialty, often take great pride in their clinical skills and can exploit their knowledge of the complexities of the nervous system to the discomfort of colleagues from other disciplines. We hope that this short piece will encourage colleagues to contribute to a series of articles, anonymously or otherwise, that describe the mistakes from which they have learned the most. These could be an enormously valuable educational resource.
Footnotes
PJ is East Midlands representative for Cardiac Risk in the Young
Provenance and peer review Commissioned; not externally peer reviewed.
Patient consent Obtained.
Competing interests None.
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