Re: What are the chances of having a second epileptic seizure?

Dear Editor

The results of a Cochrane review of seizure recurrence following first seizure have been recently reported (1,2). Fifty eight studies in adults and children underwent meta-analysis. Seizures recurrence rate was 27% at 6 months, 36% 12 months and 43% percent at 24 months.

A striking finding was the great variation in the results ranging from 8% to 58% at 6 months. In a previous authoritative review recurrence was 24% to 65% at one year(3). People with focal seizures, a structural cause or an EEG with generalised spike and wave are likely to have a higher recurrence rate. The prognosis is slightly worse in children. Treatment probably reduces the recurrence rate by one half. Recurrence rate is likely to be higher if seen in primary rather than secondary care. In established epilepsy the second seizure follows the first within a month in 30% of people. By the time patients are seen in hospital many will have already developed epilepsy and the remaining cases will have a lower recurrence. We found in neurology clinics the recurrence rate was of the order of 40% to 50% at one year, but as high as 70% for those presenting in primary care(4).

The authors of the Cochrane review acknowledge that clinical heterogeneity is probably an important reason for the varying results. For the same reason the results of the Cochrane review should be treated with caution when counselling individual patients.

Robert Elwes MD FRCP, Consultant Neurologist, King’s College Hospital
Edward Reynolds, MD FRCP, Retired Consultant Neurologist, King’s College Hospital

1.BMJ 2023;383:p2285
http://dx.doi.org/10.1136/bmj.p2285
2.Neligan_A, Adan_G, Nevitt_SJ, Pullen_A, Sander_JW, Bonnett_L, Marson_AG.
Prognosis of adults and children following a first unprovoked seizure.
Cochrane Database of Systematic Reviews 2023, Issue 1. Art. No.: CD013847.
DOI: 10.1002/14651858.CD013847.pub2.
3.Berg AT, Shinnar S The risk of seizure recurrence following a first unprovoked seizure: a quantitative review. Neurology 1991 Jul;41(7):965-72. doi: 10.1212/wnl.41.7.965.
4.Elwes RDC, Chesterman P, Reynolds EH. Prognosis after a first untreated tonic-clonic seizure. Lancet 1985; 326(8458): 752-3. PubMed ID:2864487. DOI: 10.1016/S0140-6736(85)90631-2.