Investigations

Making a diagnosis of epilepsy involves gathering information from various tests including talking to the person who suffered the seizure and anyone else who might have witnessed the seizure.

 

 

Blood test

These are useful to check for general health and other possible causes of the seizure such as an underlying disease or condition e.g. diabetes.

 

 

Electroencephalogram (EEG)

This tests informs the doctor about the activity of the brain and to identify specific epileptic tracing. During an EEG, electrodes are placed on the scalp using special glue or sticky tape. The electrodes are attached to an EEG machine. The technician may ask the patient to carryout instructions such as closing the eyes, breathing rapidly etc. The technicians may also ask the patient to look at flashing lights. The aim of the EEG is to record abnormal electrical brain activity but not necessarily to record a seizure.

 

An important point to note is that the EEG can only show what is happening in the brain at the time of the recording, so a normal EEG does not necessarily mean the condition is not present. Also an abnormal EEG does not necessarily mean that someone has epilepsy unless it shows typical epileptic activity as mentioned above.

 

An EEG is not essential for every patient who has had a seizure but is used to try and answer specific questions.

 

 

Scalp Video EEG Telemetry

The purpose of Scalp Video EEG Telemetry is to record seizures, both what they look like on a video and the associated brain electrical activity on EEG (Electroencephalogram)  A wall mounted video camera, microphone and the EEG cabling are set up at the telemetry bed. We aim to record three or more of your usual attacks, episodes or seizures. The purpose of recording both the EEG and video is to establish if any electrical changes occur in the brain prior to or during any physical symptoms you may experience.

 

 

Computerised Tomography Scan (CT Scan)

This scan is a type of x-ray which looks at the structure of the brain. It does not show if someone has epilepsy but helps to show any abnormalities which could be the cause of the epilepsy. It is not always necessary for your doctor to request that you undergo CT scanning - in many cases an MRI scan would be requested.

 

 

Magnetic Resonance imaging (MRI)

This scan also shows structural abnormalities in the brain which may be the cause of the epilepsy. This is a more powerful scanner which uses a magnetic field and radio waves but not x-ray and may pick up more abnormalities, both relevant and irrelevant than the CT scanner.

 

 

Diffusion Tensor imaging (DTI)

This type of scanner measures the movement of water in the brain as a way of detecting abnormalities which may not be picked up by a CT or MRI scanner. There are very few of these scanners in the country. Addenbrooke's Hospital does not currently have this facility.

 

 

Positron Emission Tomography (PET) and Single Photon Emission Computerised Tomography (SPECT)

In both these tests a fluid is injected to the blood stream in order to produce a picture that shows the blood flow in the brain. Any abnormalities of blood flow would be detected. These tests are not routinely offered at Addenbrooke’s unless treatment with surgery is being considered.

 

 

 

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