This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
Seizures are abnormal bursts of electrical activity in the brain that temporarily affect how it works. They can cause people to jerk or shake ('fit'), pass out, or stare blankly into space. A first seizure may be a one-off, but sometimes people go on to have another. New research provides information on how likely someone is to have a second seizure.
A seizure without an obvious cause (such as head injury or fever, for example) is called unprovoked. Someone who has two or more unprovoked seizures more than one day apart is diagnosed with epilepsy.
Researchers analysed data from 46 studies. They found that 6 months after a first unprovoked seizure, 1 in 4 (27%) people had had a second seizure. 1 year after the first seizure, that figure had risen to 1 in 3 (36%); by 2 years it was 2 in 5 (43%) people.
The researchers hope their results will help doctors counsel people on the risks of having a second seizure up to 2 years after their first.
More information on epilepsy is available on the NHS website.
What’s the issue?
More than 633,000 people in the UK have epilepsy; it is one of the most common brain disorders. Seizures vary, but symptoms include uncontrollable jerking and shaking, loss of awareness, or becoming stiff.
Epilepsy is usually a lifelong condition, but it can get slowly better over time. A diagnosis of epilepsy means that someone has had two unprovoked seizures, at least one day apart.
Seizures are common, and 1 in 25 people will have an unprovoked seizure in their lifetime. After a first seizure, many people want to know how likely they are to have a second. However, estimates vary greatly; an influential review stated that the reported risk of recurrence varied between 24 – 65%. This study aimed to provide clarity.
What’s new?
Overall, the review included 58 studies (involving 12,160 people) on the risk of a second unprovoked seizure. 46 studies were included in the analysis: 13 studies on adults (over 16s), 23 on children (1 month – 16 years), 10 on both adults and children.
The analysis concluded that, after a first unprovoked seizure:
- 1 in 4 (27%) adults and children would have had a second seizure in the first 6 months
- 1 in 3 (36%) would have had a second seizure in the first year
- 2 in 5 (43%) would have had a second seizure in the first 2 years
- children had a slightly higher chance of having a second seizure than adults.
This means that an individual's risk of having a second seizure was highest in the first 6 months, but the risk remained elevated for 2 years (and beyond).
Why is this important?
This study provides information that will help doctors to counsel people on their risk of having a second seizure.
People who have a first (provoked or unprovoked) seizure are normally banned from driving for 6 months in the UK if there are no additional identified risk factors. The restriction is increased to 12 months if they have another seizure. This study provides clarification as to how many people, on average, are expected to have a second seizure within 6 months.
The results are likely to be accurate, and the researchers say their report is based on moderate certainty evidence. This means that the true figures are likely to be close to these estimates but there is a chance that they could be substantially different. This was mostly because some studies had findings that were much higher or lower than the average.
What’s next?
The researchers are investigating what increases the chances of a second unprovoked seizure.
They recommend age groups for children and adults are standardised in future research. Data on people receiving medications should be reported separately. They call for longer-term studies (10 years and beyond) and investigation into the impact of treatment on the risk of having a second seizure.
You may be interested to read
This summary is based on: Neligan A, and others. Prognosis of adults and children following a first unprovoked seizure. Cochrane Database of Systematic Reviews 2023;1:1 – 75.
Information about seizures and epilepsy is available on the Epilepsy Action website.
Information on taking part in NIHR epilepsy studies.
A YouTube video describing what a seizure is.
Funding: This study was funded by NIHR Applied Research Collaboration North West Coast (ARC NWC).
Conflicts of Interest: Several study authors have received fees and funding from pharmaceutical companies. Full disclosures can be found in the original paper.
Disclaimer: Summaries on NIHR Evidence are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that the views expressed are those of the author(s) and reviewer(s) at the time of publication. They do not necessarily reflect the views of the NHS, the NIHR or the Department of Health and Social Care.
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