Focal Epilepsy

Focal epilepsy occurs when abnormal electrical activity repeatedly starts in a specific region of the brain. Unlike generalized epilepsy, which involves both brain hemispheres from the start, focal seizures begin in one area and may or may not spread. The seizures are classified as focal aware (consciousness preserved) or focal impaired awareness (consciousness affected), and can sometimes evolve into bilateral tonic-clonic seizures. The temporal lobe is the most common origin, but focal seizures can arise from any cortical region including the frontal, parietal, or occipital lobes. Each location produces characteristic symptoms. Diagnosis involves EEG monitoring to identify the seizure focus, MRI to look for structural causes, and sometimes advanced imaging like PET or SPECT scans. Treatment begins with anti-seizure medications, but roughly 30% of patients have drug-resistant focal epilepsy. For these patients, surgical evaluation is important, as resective surgery can be curative when a clear seizure focus is identified. Newer approaches including laser ablation, responsive neurostimulation (RNS), and vagus nerve stimulation offer additional options.