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This calculator provides data-driven predictions for individuals undergoing epilepsy surgery, incorporating key clinical, imaging, and pathological variables. The tool is designed to estimate outcomes over time using established longitudinal data from a cohort of 274 patients who underwent frontal lobe epilepsy surgery. These patients were followed up for a median period of 7.5 years, enabling the analysis of long-term surgical outcomes.

Variables

1. Age at the Time of Surgery (<30 vs. ≥30 years):

• The tool categorizes individuals based on age at the time of surgery, grouping them into younger patients (under 30 years) and older patients (30 years and above).

2. Anti-Seizure Medications (ASMs) at the Time of Surgery (<4 vs. ≥4 ASMs):

• Patients are grouped by the number of anti-seizure medications they are prescribed at the time of surgery.
  • Fewer than four ASMs typically indicates lower medication dependency.
  • Four or more ASMs often reflects drug-resistant epilepsy and higher disease burden.

3. MRI Findings (Focal Abnormality vs. Diffuse Abnormality/Normal MRI):

• Imaging findings are classified into two categories:
  • Focal Abnormality: Defined as localized lesions that can be precisely identified on MRI scans, suggesting a specific pathological source of epilepsy.
  • Diffuse Abnormality/Normal MRI: Includes cases with widespread or poorly defined abnormalities, or normal imaging findings.

4. Pathology Type:

The pathological findings from resected brain tissue are categorized into the following groups based on histopathological examination:

• Focal Cortical Dysplasia (FCD):
  • A developmental cortical malformation frequently associated with drug-resistant epilepsy. Diagnosis is confirmed through the presence of disrupted cortical layers, balloon cells, or other architectural anomalies.
• Dysembryoplastic Neuroepithelial Tumor (DNET):
  • A benign glioneuronal tumor that commonly presents with longstanding epilepsy. Histological features include specific patterns of neuronal and glial cells within a myxoid matrix.
• Cavernoma:
  • A vascular malformation composed of dilated, thin-walled blood vessels. Pathological examination often reveals hemosiderin deposits and surrounding gliosis, consistent with repeated micro-hemorrhages.
• Gliosis:
  • A reactive condition characterized by astrocyte proliferation in response to injury, inflammation, or disease. The absence of neoplastic changes distinguishes gliosis from other pathologies.
• Glioma:
  • Encompasses low- and high-grade tumors derived from glial cells, with classification based on the World Health Organization (WHO) grading system. Histological features include atypical cellular growth and mitotic activity, depending on the tumor grade.

Outcomes

Risk of Seizure Recurrence:

• This model estimates the cumulative probability of seizure recurrence after surgery.

Chance of an Occurrence of a Seizure in the next Year:

• The calculator also predicts the expected chance of seizure likelihood in the year following a selected time point.