Objective To determine reasons for adult patients with drug-resistant focal epilepsy who undergo presurgical evaluation not proceeding with surgery and identify factors that influence this decision.

Methods We analyzed demographic, imaging and electroclinical data on 617 consecutive patients brought to the Queen Square presurgical epilepsy MDT between January 2015 and December 2019. Multivariable logistic regression was performed to identify predictors of not proceeding with surgery, using comparative data from a prospectively-followed cohort of individuals who had epilepsy surgery at the same centre over an identical 5-year period.

Results A definitive decision not to proceed with surgery was made in 315 (51%) cases. Common reasons behind this were an inability to localise the epileptogenic zone (n=104), multifocal epilepsy (n=74) and patients’ decisions not to proceed with intracranial EEG (n=50) or surgery (n=39). Learning disability (OR: 2.35; 95% CI 1.07-5.16), normal MRI (OR: 6.68; 95% CI 3.71-12.05), extratemporal epilepsy (OR: 2.93; 95% CI 1.82-4.71) and bilateral seizure onset zones (OR 3.05; 95% CI 1.41-6.61) were independent predictors of not having surgery. Probability of having surgery in those with normal MRI and extratemporal epilepsy was <10%. Those who did not proceed to surgery resided in more deprived socio-economic areas (median deprivation decile 40-50% vs 50-60%, p<0.05).

Conclusions Although underutilized, epilepsy surgery is only appropriate for selected individuals with drug-resistant focal epilepsy. A predictive model based on demographic, imaging and electroclinical data can help determine those unlikely to be suitable for surgery and aid the decision to refer for more extensive or invasive evaluation.