National Institute for Health and Clinical Excellence (NICE)
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Serious causes behind blackouts under-recognised, warns NICE

People who experience spontaneous blackouts may not be receiving accurate or timely diagnoses because of inadequate assessments made by healthcare staff. NICE is publishing a clinical guideline today (25 August) which hopes to improve the diagnosis and management of this potentially serious symptom.

Around half of the UK population will experience blackouts (known medically as transient loss of consciousness) at some point in their lives. For most people, these will have a simple explanation; for example, if a person has been standing for a long time, feels stressed or anxious, or if they have had a sudden exposure to an unpleasant sight or experience.

However blackouts can also have a cardiovascular or neurological cause, such as heart disease or epilepsy, which may be undetected or misdiagnosed if the necessary checks are not made when the person is first examined by their GP, paramedic or other healthcare professional.

Dr Fergus Macbeth, Director of the Centre for Clinical Practice at NICE said: "Although transient loss of consciousness is a very common symptom that the NHS deals with on a daily basis, its diagnosis can often be inaccurate, inefficient and delayed. For example, some people with epilepsy may also have a heart problem which has caused them to blackout, which could initially be overlooked as the healthcare professional may believe that he or she already has the correct diagnosis. Lapses such as these could lead to delays in treatment for the cardiovascular cause, which subsequently could put the patient’s health at further risk.

"Our clinical guideline hopes to address the huge variation in clinical practice across the NHS, regarding what healthcare professionals should do when they are first presented with people who may have experienced blackouts, as well as when they should consider referring them to specialists for further investigation. It has been based on the most up to date research and so represents best practice for the NHS."

NICE advises healthcare professionals to establish the specific circumstances that occurred before, during and after the suspected blackout, either directly from the person, or from any witnesses. They should also record their medical history and vital signs. Following this:

  • If the initial assessment does not reveal any concerns and if the blackout is symptomatic of an uncomplicated faint, then no further immediate management may be required.
  • However, if there are uncertainties, the healthcare professional should offer a number of tests, including a 12-lead electrocardiogram (ECG). If this reveals possible abnormalities, or if it transpires that the person has a family history of heart disease, has blacked out during exertion, or has unexplained breathlessness, then this may indicate that the underlying cause could be cardiovascular. The NICE guideline then advises that the person should be referred to a cardiovascular specialist within 24 hours for further tests.
  • Alternatively, if a witness reveals that the person suffered limb-jerking or bit his or her tongue during the blackout, or experienced confusion or disorientation once they regained consciousness, then this could mean that the cause is neurological. The guideline advises that the person should then be seen by an epilepsy specialist within 2 weeks.

Dr Paul Cooper, a Consultant Neurologist and Chair of the Guideline Development Group said: "While most people will have a situational or uncomplicated cause for their blackout, which doesn’t require a referral to a specialist, the NICE guideline calls for all healthcare professionals carrying out the initial assessment to assume the symptom is serious until proven otherwise. There are lots of possible causes for transient loss of consciousness and so having a standardised, clinical pathway is crucial."

Dr Greg Rogers, a GP and Guideline Developer said: "The guideline is important as it recognises that patients often present with symptoms rather than diagnoses. Healthcare professionals should gather as much information as possible when they first examine people who may have experienced blackouts so that they can establish an accurate account of what happened before, during and after the episode. The participation of a witness can greatly support this."

Mrs Julie Fear, patient member from the Guideline Development Group said: "From the age of ten, I suffered from recurring blackouts, which eventually led doctors to believe that I had a form of epilepsy. This had a huge impact on my life as I had to take medication to control my seizures and missed out on many childhood experiences like sleepovers and parties. I felt very different from others my age and my self esteem and confidence subsequently became very low. After the birth of my third child, I was given an opportunity to revisit my diagnosis and found out that I actually had a heart problem called an arrhythmia, which was treated on the same day with a pacemaker. Although I am now able to live life to the full, it angers me that for nearly thirty years I had been burdened with a condition that I didn’t actually have.

"I hope this guideline from NICE will ensure that people like me are given the appropriate attention from healthcare staff straightaway so that they can be given a correct diagnosis as quickly as possible, and get the treatment they need."

Trudie Lobban, Chief Executive and Founder of Syncope Trust And Reflex anoxic Seizures (STARS) charity said:

"It is clear from my own experience with my daughter who suffered from blackouts and from the thousands of people who have contacted STARS that we need to improve the diagnosis and management of TLoC in the UK. By following the NICE guideline, healthcare professionals will be better able to accurately and quickly diagnose the cause of a blackout and they should go some way to reducing Sudden Cardiac Death, which is the number one killer in the UK. We aim to promote the new guidelines by providing patient support, education and guidance, improving access to appropriate treatments. STARS has resources and models available to support this."


Notes to Editors

About transient loss of consciousness (TLoC)

1. TLoC is the medical term for a blackout and can be defined as spontaneous loss of consciousness with complete recovery (i.e. without any residual neurological deficit).

2. There are various causes of TLoC, the most common of which is a reduced supply of blood to the brain due to uncomplicated factors such as sudden exposure to an unpleasant sight or experience, standing for a long time, a sudden episode of stress, emotional upset, fear or anxiety, or if they have spent a long time in a hot or stuffy environment - this is known commonly as fainting.

3. However, people can also experience TLoC due to cardiovascular disorders, conditions relating to the brain and nervous system (such as epilepsy) and emotional factors.

4. Because there are many possible causes of TLoC, healthcare professionals may have to conduct a number of assessments to find out the underlying cause. NICE has outlined the most effective diagnostic assessments that they should carry out, as well as when they should consider referring the patient to a cardiovascular or neurological specialist for further investigation.

5. TLoC accounts for 6% of all urgent hospital admissions.

About the clinical guideline

View the NICE clinical guideline 109 on "The management of transient loss of consciousness (blackouts) in adults" for further information. The page includes a version of the guideline, specifically written for patients and members of the public.

About NICE

1. The National Institute for Health and Clinical Excellence (NICE) is the independent organisation responsible for providing national guidance on the promotion of good health and the prevention and treatment of ill health.

2. NICE produces guidance in three areas of health:

  • public health - guidance on the promotion of good health and the prevention of ill health for those working in the NHS, local authorities and the wider public and voluntary sector
  • health technologies - guidance on the use of new and existing medicines, treatments, procedures and medical technologies within the NHS
  • clinical practice - guidance on the appropriate treatment and care of people with specific diseases and conditions within the NHS.


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