Assessments for surgery
To decide if you are suitable for epilepsy surgery we will carry out different tests and assessments to find out where in your brain your seizures are coming from, and whether this area could be operated on without causing additional problems to you.
Assessments will also be done to assess your memory, language, understanding (cognition), as well as the effect of seizures on daily life, mood, behaviour and social relationships.
These investigations will involve several outpatient and inpatient visits to the hospital and the results of all these investigations are discussed by a panel of experts (multidisciplinary team assessment – MDT), who will decide if epilepsy surgery is an option for you.
We will write a letter to you, your GP and your local consultant to let you know what the MDT have decided and if surgery is a possible option for you, you will be invited to meet the Epilepsy Surgery Team in the Epilepsy Surgery Clinic to discuss if you would like to go ahead with the surgery.
We aim to make sure these assessments are done as smoothly and a quickly as possible, but this may vary depending on what tests will be done.
Types of investigations you may have
Before any of these assessments your consultant will talk to you to make sure that you are prepared and know what to expect.
- Electroencephalogram (EEG)
- Video Telemetry (VT)
- Magnetic Resonance Imaging (MRI Scan)
- Functional MRI scan (fMRI Scan)
- Magnetoencephalography (MEG Scan)
- Positron Emission Tomography (PET Scan)
- Neuropsychometric Assessment
- Neuropsychiatry Assessment
- Therapy Assessment
- Invasive EEG Monitoring
- Single-photon emission computed tomography (SPECT scan)
During the EEG, electrodes are placed onto your scalp using a special type of glue or tape. The electrodes will then be connected to the EEG machine which records the electrical signals in the brain. The machine tells us where the epileptic electrical activity is coming from within the brain.
Video Telemetry is where you will have the EEG electrodes attached to your head and also be filmed. For this to happen, you will need to come into hospital for a period of up to five days - usually on a Monday and discharged on a Friday. You will stay on the ward where a video camera is attached to your bed to capture your seizures. This is so that we can see when you're having a seizure and from which part of the brain the abnormal epileptic electrical activity is coming from.
There may be occasions - particularly when you do not have very regular seizures - that your medication will be reduced so that we can allow a seizure to happen. This will only be done when you're in hospital so that you can be monitored in a safe environment.
The purpose of doing an MRI scan is to see whether there is a structural cause for your epilepsy. You will lie on a table which will slide you into a scanner. Thanks to its radio waves and magnetic field, the MRI scanner is very powerful and can pick up the smallest abnormalities that are causing epilepsy. It is important that with MRI scans that you lie absolutely still as any movement can affect the scans and they may have to be redone. To try and avoid this, we might ask for the scan to be done with a general anaesthetic so that we can guarantee that there will be no movement during the scan to avoid multiple scans and to avoid delays in your treatment.
This scan is done with our partners at Aston University's Brain Centre. This scan is very similar to an MRI scan. You still lie on the table in the scanner, but while you're being scanned, you will be asked to do some tasks. This may include saying words that appear on a screen, or tap your fingers and thumb, or look at pictures and say what they are. The idea of this is that when you do these tasks, your brain has an increase flow of oxygen to specific areas of the brain, helping us to see the areas of the brain that control thoughts, speech, movement and sensation. This scan might be requested if the area where the epilepsy is believed to be coming from areas that control thoughts, speech, movement and sensations.
This scan is also performed at Aston University's Brain Centre. MEG scans are similar to fMRI scans because you will be asked to do some tasks, but the difference is that you don't have to lie down and slide into the scanner, you sit in a chair and the scanner sits above you like a giant hairdryer.
This scan is done at St Thomas’s Hospital in London. St Thomas’s Hospital is a leading hospital for PET scans and they do them on behalf of many hospitals in England. This scan uses a tracer, which is a radioactive substance that is injected into you to find out how your brain is working. Usually, they will also do an EEG at the same time to compare the images to the EEG without the radioactive substance. The PET scan shows which part of your brain is causing the epileptic activity because that part does not soak up the tracer as much as the normal brain.
Every child that we deem to be suitable for epilepsy surgery will have a Neuropsychology assessment. This assessment is normally carried out over a few hours where you will be asked to complete different tasks. Some of them will be regarding your memory, some about your written skills, some about your speech skills and some about your number skills. Your parents will also have to fill in a questionnaire about how epilepsy has affected your life and skills. The idea of this assessment is to see whether the area within your brain that we are considering doing surgery on is responsible for any important functions. This assessment is also useful to determine if your epilepsy has left you with any memory or learning problems. This assessment is often used to assist in gaining extra help at school if such difficulties have been identified. If you go onto have surgery, this assessment is completed again a year after surgery to compare how you were before and after surgery.
Sometimes our team feels that having a Neuropsychiatry assessment as part of your initial assessment helps you to understand the effects that epilepsy is having on you. As it is common for children with epilepsy to have emotional and behavioural problems, a psychiatrist with experience in epilepsy surgery will identify if you are having such difficulties. They may also be able to suggest treatments for any difficulties you may be having - whether you were to have surgery or not.
Depending on the type of surgery that you may go on to have and your age, it might be beneficial to have a Therapy assessment of your speech and mobility skills - before and after surgery. This is done by out Therapy team either as an inpatient just before your surgery or in an outpatient clinic depending on individual circumstances and condition. We do this assessment because after surgery you may feel weaker and you may feel like you need a bit of extra help to get you back to your original strength. When you're sent home from hospital, the Therapy team will liaise with the teams that you may already be working with in your local area, to carry on with your different therapies. If you have a therapy assessment prior to surgery, this will be repeated 3 months and 12 months after you have had surgery.
Invasive monitoring is a surgical procedure that incorporates an EEG, but in this investigation the electrodes are attached to the surface or deep inside the brain instead of the scalp. You may have invasive monitoring if your consultants have an idea of where the seizures are coming from, but are not exactly sure. While this invasive monitoring is done, the surgeon can also map exactly which part of your brain is responsible for speech, memory and movement.
When you come in for Invasive Monitoring, you will be anaesthetised and taken to theatre for the electrodes to be put onto the surface or deep inside your brain, before moving to the ward to be connected to the EEG machine. Once the electrodes have been in for enough time, you will then be taken back to theatre for the electrodes to be removed. If the consultants have gathered enough information, you may then have epilepsy surgery straight after the invasive monitoring is removed, to avoid further surgeries.
Single-photon emission computed tomography (SPECT scan)
You will be given an injection of a radioactive dye which goes to your brain. The dye highlights different areas of blood flow within your brain. Usually, blood flow is higher in the part of the brain where the seizures start. There are two types of SPECT scan. One is called an inter-ictal scan which is done when you have not had a seizure. The other is called an ictal SPECT which is done just after you have a seizure. The scan shows the different areas of blood flow in different colours, so the idea is that the area that the seizure starts from is highlighted by the scan.