One of the most important ways to make a diagnosis of epilepsy is through the use of brain scans. The most commonly used brain scans include:
- CT (computed tomography)
- PET (positron emission tomography)
- MRI (magnetic resonance imaging).
CT and MRI scans reveal the structure of the brain, which can be useful for identifying brain tumors, cysts, and other structural abnormalities. PET and an adapted kind of MRI called functional MRI (fMRI) can be used to monitor the brain's activity and detect abnormalities in how it works. SPECT (single photon emission computed tomography) is a relatively new kind of brain scan that is sometimes used to locate seizure foci in the brain.
In some cases, doctors may use an experimental type of brain scan called a magnetoencephalogram, or MEG. MEG detects the magnetic signals generated by neurons to allow doctors to monitor brain activity at different points in the brain over time, revealing different brain functions. While MEG is similar in concept to EEG, it does not require electrodes and it can detect signals from deeper in the brain than an EEG.
Doctors also are experimenting with brain scans called magnetic resonance spectroscopy (MRS) that can detect abnormalities in the brain's biochemical processes, and with near-infrared spectroscopy, a technique that can detect oxygen levels in brain tissue.
Doctors often take blood samples for testing, particularly when they are examining a child. These blood samples are often screened for metabolic or genetic disorders that may be associated with the seizures. They also may be used to check for underlying problems (such as infections, lead poisoning, anemia, or diabetes) that may be causing or triggering the seizures.