Metabolic syndrome as a modifiable risk factor for complications after epilepsy surgery

Metabolic syndrome (MetS) is a growing public health concern in what has been called a "global epidemic." The aim of this study was to investigate how MetS influences postoperative seizure freedom outcomes and complications following elective neurosurgical intervention for drug-resistant epilepsy (DRE), offering an opportunity to uncover modifiable outcome drivers.

Adult patients with DRE who underwent a first resective epilepsy surgery from 2000 to 2017 were identified retrospectively from a prospectively collected institutional outcomes registry. MetS was defined as having ≥ 3 of 4 diagnostic criteria: obesity, hyperglycemia, hypertension, or dyslipidemia. Patients who met 2 criteria preoperatively (pre-MetS cohort) and patients who met ≥ 3 criteria preoperatively (MetS cohort) were matched with non-MetS patients by using covariates classically linked with surgical outcomes, including age at surgery, sex, epilepsy duration, seizure frequency, prior generalized tonic-clonic seizures, abnormal MRI findings, handedness, surgical type, and Charlson Comorbidity Index. Differences in postoperative complications and ICU admissions within 30 days and hospital length of stay (LOS) were analyzed using risk ratios and the average treatment effect (ATE). Differences in postoperative seizure freedom outcomes were quantified using Kaplan-Meier analyses.

Propensity score matching (PSM) achieved a symmetric covariate balance between the pre-MetS and MetS cohorts and their non-MetS counterparts (standardized mean difference after PSM < 0.1 and ≤ 0.25, respectively). Of 1466 patients who underwent surgery for DRE, 441 (30.1%) met ≥ 2 diagnostic criteria (pre-MetS cohort, n = 339; MetS cohort, n = 102). The pre-MetS cohort had higher postoperative complication rates (RR 1.25, 95% CI 1.04-1.52) and longer LOS (ATE 1.02 [SE 0.34], p = 0.01) compared with the matched non-MetS cohort, but did not differ significantly with respect to postoperative ICU admissions (RR 1.59, 95% CI 0.66-3.83). Patients with MetS had a higher risk of postoperative complications (RR 1.99, 95% CI 1.39-2.86) than non-MetS patients, although differences in ICU admission (RR 1.32, 95% CI 0.47-3.74) and LOS (ATE 0.72 [SE 0.43], p = 0.20) between groups were insignificant. There were no significant differences in postoperative seizure freedom outcomes between the pre-MetS or MetS cohorts and their non-MetS counterparts (p = 0.52 and p = 0.71, respectively).

Preoperative MetS could increase the risk of major postoperative morbidity after resective epilepsy surgery. Early identification and management of MetS components could be important for optimizing surgical outcomes for patients with DRE.