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Low IQ predicts worse long-term seizure outcome after resective epilepsy surgery - A propensity score matched
Jesper Reinholdson1, Ingrid Olsson2, Anna Edelvik Tranberg3
1Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at Gothenburg University, Gothenburg, Sweden.
Insights
Patients with low IQ (<70) undergoing epilepsy surgery have worse seizure control compared to those with higher IQs. However, surgery can still offer significant seizure reduction for individuals with intellectual disability.
Area of Science:
- Neurology
- Neurosurgery
- Epileptology
Background:
- Focal resective epilepsy surgery is a treatment option for drug-resistant epilepsy.
- Intellectual disability (ID) is common in epilepsy, and its impact on surgical outcomes is crucial to understand.
Purpose of the Study:
- To evaluate long-term seizure outcomes in patients with intellectual disability (IQ < 70) after resective epilepsy surgery.
- To determine if baseline IQ predicts seizure control post-surgery.
Main Methods:
- Analysis of a population-based cohort of patients undergoing resective epilepsy surgery (1995-2017).
- Comparison of seizure outcomes between patients with IQ < 70 and IQ ≥ 70, including propensity score matching.
- Assessment of 2-year, 5-year, and long-term (10-20 year) seizure outcomes.
Main Results:
- Patients with IQ < 70 had significantly worse seizure outcomes at all follow-up points compared to those with IQ ≥ 70.
- Long-term seizure freedom rates were 28-32% for IQ < 70 group vs. 54-62% for IQ ≥ 70 group post-matching.
- A substantial proportion (29-45%) of patients with IQ < 70 achieved ≥ 75% seizure frequency reduction.
Conclusions:
- Low preoperative IQ is a predictor of reduced seizure freedom after resective epilepsy surgery.
- While complete seizure freedom is less common in patients with intellectual disability, resective surgery offers significant palliative benefits with substantial seizure reduction.
Objective:
To describe long-term seizure outcomes in patients with IQ < 70 undergoing resective epilepsy surgery and to analyse whether baseline IQ predicts seizure outcome.
Methods:
Patients undergoing focal resective epilepsy surgery 1995-2017 at age ≥ 4 years were identified in the population-based Swedish National Epilepsy Surgery Register. Two-year, five-year and long-term (10-20-year follow-up) outcomes were analysed. Seizure outcomes of patients with IQ ≥ 70 and IQ < 70 at baseline were compared in the full cohort and between propensity score matched groups.
Results:
Follow-up data were available for 884 patients, 79 of whom had IQ < 70. Matched controls were found for 74 of the IQ < 70 patients. Preoperative MRI pathology was unifocal in 54 % and 79 % of IQ < 70 and IQ ≥ 70 patients before matching compared to 58 % and 62 % after matching, respectively. Patients with IQ < 70 achieved significantly worse seizure outcomes at all time points both when analysing the full cohort and the matched groups. After matching, the proportions of seizure-free patients in the IQ < 70 group were 28 %, 32 % and 32 % at the 2-year, 5-year and long-term follow-ups, respectively. Corresponding figures in the IQ ≥ 70 group were 54 %, 62 % and 60 % (p for difference between IQ groups 0.004, 0.002 and 0.049). In the IQ < 70 group, 36 %, 29 % and 45 % had a ≥ 75 % reduction in seizure frequency at the respective three follow-ups.
Conclusion:
Low preoperative IQ predicts lower chances of seizure freedom after resective epilepsy surgery and few patients with IQ < 70 remain completely seizure-free in the long term. Nevertheless, a significant proportion had a reduction in seizure frequency of at least 75 % at long-term follow-up, indicating an important palliative potential of resective surgery for epilepsy patients with intellectual disability.
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