Which diagnostic tool is best suited for evaluating focal seizures in epilepsy?

Electroencephalography (EEG) is the best diagnostic tool for evaluating focal seizures in epilepsy because it directly measures electrical activity in the brain using electrodes placed on the scalp. This allows for real-time monitoring of brain activity and is particularly effective at detecting the abnormal electrical discharges that characterize seizures, especially focal ones. During an EEG, the specific patterns associated with different seizure types can be identified, providing crucial information for diagnosis and treatment planning.

In contrast, while magnetic resonance imaging (MRI) is valuable for visualizing the structure of the brain, it does not provide information about electrical activity, which is essential for diagnosing and understanding the nature of seizures. Computed tomography (CT) is similarly limited, as it primarily assesses structural abnormalities but lacks the capability to capture the dynamic electrical changes that occur during a seizure. Single-photon emission computed tomography (SPECT) can evaluate blood flow during seizures but is less commonly used compared to EEG for real-time seizure assessment.

Therefore, EEG stands out as the preferred method for diagnosing and evaluating focal seizures in patients with epilepsy.