Diagnostic Services

The Epilepsy Program works with Cedars-Sinai's diagnostic imaging experts who use industry-leading technology. This coordinated approach allows our experts to diagnose the causes of seizures with precision and detail, leading to uniquely personalized care plans for patients.

Diagnostic tests for epilepsy may include:

  • CT scan
  • Electroencephalogram (EEG)
  • Magnetic resonance imaging (MRI)
  • Continuous video-EEG/long-term monitoring — Patients usually spend five to seven days in the Epilepsy Monitoring Unit for a comprehensive, noninvasive, differential or pre-surgical evaluation. A registered EEG technologist places electrodes on the patient's head using an adhesive. The electrodes are then connected to a continuous EEG and video recording system that records the seizures. This data helps the epilepsy team determine the most effective course of treatment and management.
  • Ictal SPECT study — Single photon emission computerized tomography (SPECT) is a nuclear medicine study that uses a radioactive tracer to map blood flow to the brain. Ictal means the scan is performed just after a seizure. The study compares blood flow between seizures (ictal) and the blood flow when seizures are not occurring (interictal). The test is performed during a hospital stay, since the scan is performed during a seizure. During a seizure, blood flow typically increases in the region where the seizure starts. A tracer (Neurolite) is injected as soon as possible after the seizure starts, usually within 30 seconds. The SPECT scan is then performed within two to four hours of the injection. The study shows the part of the brain with increased activity.
  • FDG PET scan — The positron emission tomography (PET) scan uses a very low and safe dose of a radioactive isotope to map the use of glucose in the brain. Parts of the brain related to seizures sometimes use less glucose and are called hypometabolic areas.
  • Neuropsychological evaluation — A neuropsychological evaluation is used to measure cognitive function in patients who may be candidates for surgery. Patients may have weaknesses in certain tasks that are typical for the right temporal lobe, left temporal lobe or frontal lobe. These weaknesses may help point out the areas affected by seizures and give clues as to where seizures are originating.
  • Intracarotid sodium amobarbital test (Wada) for memory and speech lateralization — The Wada test is an invasive procedure that's similar to having an angiogram. The procedure is performed on an outpatient basis. After the procedure, the patient is sent to a recovery room for a limited time (under six hours) and is discharged once stable.
  • Ictal and interictal magneto-encephalogram (MEG) study — A magneto-encephalogram is used to measure the magnetic field activity of the brain between seizures (interictal), and in some cases during seizures (ictal). The patient is placed in a magnetic-shielded room and magnetic sensors are placed above their head. EEG activity is measured and the source of abnormal MEG is determined. The patient's head shape is mapped in a digital format with 3-D coordinates. The coordinates or sources are co-registered on an MRI of the patient's brain. The abnormal epileptiform magnetic activity of the brain is displayed on the MRI.