Dario J. Englot, Mitchel S. Berger, Nicholas M. Barbaro and Edward F. Chang
Seizures are the most frequent presenting symptom in patients with low-grade gliomas (LGGs), and significantly influence quality of life if they are uncontrolled. Achieving freedom from seizures is of utmost importance in surgical planning, but the factors associated with seizure control remain incompletely understood.
The authors performed a systematic literature review of seizure outcomes after resection of LGGs causing seizures, examining 773 patients across 20 published series. Rates of seizure freedom were stratified across 7 variables: patient age, tumor location, preoperative seizure control with medication, seizure semiology, epilepsy duration, extent of resection, and the use of intraoperative electrocorticography (ECoG).
Gross-total resection was most predictive of complete seizure freedom, when compared with subtotal resection (OR 3.41, 95% CI 2.36–4.93). Other predictors of seizure freedom included preoperative seizure control on antiepileptic medication (OR 2.12, 95% CI 1.33–3.38) and duration of seizures of ≤ 1 year (OR 1.85, 95% CI 1.22–2.79). Patients with simple partial seizure semiology achieved seizure freedom less often than those with complex partial, generalized, or mixed seizure types (OR 0.46, 95% CI 0.26–0.80). No significant differences in seizure outcome were observed between adults versus children, patients with temporal lobe versus extratemporal tumors, or with the use of intraoperative ECoG.
Seizure control is one of the most important considerations in planning surgery for low-grade brain tumors. Gross-total resection is a critical factor in achieving seizure freedom.
Nathan C. Rowland, Dario J. Englot, Tene A. Cage, Michael E. Sughrue, Nicholas M. Barbaro and Edward F. Chang
Focal cortical dysplasia (FCD) is one of the most common causes of medically refractory epilepsy leading to surgery. However, seizure control outcomes reported in isolated surgical series are highly variable. As a result, it is not clear which variables are most crucial in predicting seizure freedom following surgery for FCD. The authors' aim was to determine the prognostic factors for seizure control in FCD by performing a meta-analysis of the published literature.
A MEDLINE search of the published literature yielded 37 studies that met inclusion and exclusion criteria. Seven potential prognostic variables were determined from these studies and were dichotomized for analysis. For each variable, individual studies were weighted by inverse variance and combined to generate an odds ratio favoring seizure freedom. The methods complied with a standardized meta-analysis reporting protocol.
Two thousand fourteen patients were included in the analysis. The overall rate of seizure freedom (Engel Class I) among patients undergoing surgery for FCD in the cohort of studies was 55.8% ± 16.2%. Partial seizures, a temporal location, detection with MRI, and a Type II Palmini histological classification were associated with higher rates of postoperative seizure control. As a treatment-related factor, complete resection of the anatomical or electrographic abnormality was the most important predictor overall of seizure freedom. Neither age nor electroencephalographic localization of the ictal onset significantly affected seizure freedom after surgery.
Using a large population cohort pooled from the published literature, an analysis identified important factors that are prognostic in patients with epilepsy due to FCD. The most important of these factors—diagnostic imaging and resection—provide modalities through which improvements in the impact of FCD can be effected.