One Goal. One Passion. Every Patient. Every Time.
epilepsy

Diagnostic Tests for Epilepsy

A single seizure does not necessarily mean that a person has epilepsy. It does, however, merit further examination and testing to ensure a precise diagnosis. In cases where surgery is recommended, additional tests can help surgeons best prepare for the operation.

EEG

There are many types of epilepsy and epilepsy-related syndromes. Other conditions, such as narcolepsy, cardiac syncope, and arrhythmia, mimic some of the symptoms of epilepsy. An excellent tool to help determine a specific diagnosis is the electroencephalogram, or EEG. During this non-invasive test, several electrodes are placed on a patient’s scalp. They record electrical impulses from the brain known as brain waves. The results of an EEG can be printed out and interpreted by an epileptologist.


An EEG printout shows seizures starting in the left temporal region.

Because a non-invasive EEG can only measure electrical activity on the brain’s surface, sometimes the readings come back normal when, in fact, there is abnormal activity deeper in the brain. In certain cases, the electrodes are implanted surgically through tiny holes in the skull to obtain a more precise reading.

Continuous Video EEG Monitoring

It is helpful for the epileptologist to study the brain waves over time. This can be accomplished through continuous video EEG monitoring, where a patient stays in a special unit for at least 24 hours. Antiepileptic medication is stopped for the duration of this test, as the objective is for seizures to occur so the abnormal brain waves they produce can be recorded.

A video camera connected to the EEG provides constant monitoring, enabling the medical team to pinpoint the area where a seizure occurs and track the patient’s physiological response to the seizure. Continuous monitoring can also help distinguish between epilepsy and other conditions, characterize the seizure type for more precise medication adjustments, and prior to surgery, locate the originating area of seizures within the brain.

During periods when they are not having a seizure or undergoing neuropsychological testing, patients can have visitors, read, and watch TV.

The Wada Test

When surgeons operate to relieve seizures, they need to know all they can about the structure of the patient’s brain. The intracateroid sodium ambobarbital, or Wada test, helps to identify the areas of a person’s brain that control speech and memory functions. During this pre-operative procedure, an angiogram of the brain is taken (an X-ray of the brain’s blood vessels). A drug is then injected into the patient that anesthetizes one side of the brain; the patient is asked to respond to a series of memory and speech-related tests. From this test, the neurosurgical team can determine where the areas of the brain that control speech and memory are located, and thus avoid those areas during surgery.

Magnetic Resonance Imaging (MRI) and Functional MRI

This equipment uses a magnetic field rather than radiation to capture an image. By scanning at different angles, it can provide a 3-dimensional image of the brain.


A traditional MRI Scan of the hippocorpus, a brain region that frequently gives rise to seizures.
 
A functional MRI Scan showing blood flow changes during motor activity - as seen in red and yellow.

Functional MRI takes images in "real time" sequence and faster than traditional MRI. This technique often is used before surgery to create a map of the brain and indicate where language, motor, and sensory areas are located. During the scan, the patient is asked to perform certain tasks, such as tapping fingers or repeating a list of words. From the image, the neurological team can locate the area of the brain controlling that function.

SPECT

Single Photon Emission Computed Tomography, or SPECT, is a scanner that measures a low-dose radioactive material as it circulates through the brain. SPECT can track cerebral blood flow and detect alterations in brain metabolism between and during seizures. This information can be useful in locating the seizure focus–the place within the brain where a seizure originates.

The bright yellow area in this SPECT image shows an increase in brain metabolism, representing the seizure focus.

Computed Tomography (CT)

By using this combination of a sophisticated X-ray device and a computer, the brain’s structure and tissues can be imaged. The Center uses a state-of-the-art scanner to produce images with unprecedented speed and image clarity.

The CT scan allows physicians to see fine details of the brain's structure and tissue, to see abnormalities, or the absence of abnormalities - as pictured left.

Neuropsychological Testing

A patient’s cognitive abilities, memory, and motor skills often are assessed through a variety of neuropsychological tests.

Return to Top