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Oxford University Hospitals NHS Foundation Trust
Epilepsy Surgery Service

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Assessments

The risks and benefits of epilepsy surgery specific to you will be evaluated extensively in the assessment process.

Surgical assessment process

The aim of the assessment process is to identify the likely risks and benefits for you. The assessment looks to determine the exact location of seizure focus (where the seizures begin), and assess whether the surgery would interfere with other brain functions such as memory, speech, or your visual field.

The assessment also explores your wellbeing, your expectations and your understanding of surgery.

It may take several months to complete the assessment, and even after these tests are completed you may be found not to be eligible for surgery. If you are found to be suitable, we will give you time to decide if you would like to pursue epilepsy surgery.

Initial consultation

If a referral is appropriate, we will refer you for an initial consultation with one of our consultant neurologists.

This will involve a review of your medical history, your diagnosis, treatment and treatment response. This information may indicate that surgery could be a treatment option and we will refer you for further assessments. Please use this meeting to discuss the aims of the surgery and ask any questions you may have.

If we refer you for a consultation, please complete our questionnaire:

Oxford Epilepsy Service outpatient questionnaire (pdf, 291KB)

If we decide that you are eligible to begin the epilepsy surgery assessment process, then we will add you to the waiting list for a number of tests and scans, outlined below.

Tests and scans

Electroencephalogram (EEG)

An Electroencephalogram (EEG), or brain wave test, is an essential part of the assessment process. It is likely that you would already have had an EEG as part of the diagnostic assessment, however a more up-to-date EEG may be required.

The assessment also involves a Video Telemetry EEG assessment. This is a continuous brain wave and video monitoring assessment. This may involve reducing your medication in the hope of capturing a seizure. This test will be over several days and will therefore require an admission to hospital.

In some cases, an Intracranial EEG may be required. This is conducted when the standard EEG assessments above are not able to determine where the seizures are starting from. This is an invasive procedure and will involve a hospital stay. We will discuss this in detail with you if it is needed.

Brain scans

You will have a Magnetic Resonance Imaging (MRI) scan as part of the assessment process. This is to identify the cause of your seizures and will be used alongside the EEG findings.

A Positron-Emission Tomography (PET) scan may be required to locate the seizure focus in more complex cases, in addition to the MRI scan.

What is it like having a PET Scan? - YouTube.com

For more information on other types of tests that could be involved in the assessment process please visit the Epilepsy Action website:

Epilepsy surgery for adults - www.epilepsy.org.uk

Neuropsychological Assessment

This is a routine assessment which contributes further information about whether surgery could be helpful. The neuropsychological assessment involves an initial discussion with the Consultant Clinical Neuropsychologist and an in-depth assessment of your cognition (memory and thinking). This will usually involve two visits to the clinic.

The discussion will focus on how epilepsy has affected your life generally and on your memory and thinking in particular. We will ask you to complete a range of activities/assessments that aim to gather information about your memory and other thinking skills.

There are two main reasons for this.

  • The pattern of strengths and weaknesses in memory and thinking skills can provide further information about where your seizures are coming from.
  • This information can allow us to predict the effects of surgery on your memory and thinking and highlight any risks that you will need to consider.

For some people, a further assessment called a Wada test or amytal procedure will be necessary to confirm that surgery will not lead to a significant memory or speech difficulty. This procedure requires a brief (one night) admission to hospital. It involves very briefly anaesthetising the left and right sides of the brain separately so that the memory and speech abilities of the non-anaesthetised side can be assessed. If we consider this further assessment necessary, we will discuss it fully with you beforehand.

There is further information about neuropsychological assessment in this leaflet: Adult Clinical Neuropsychology (pdf)

Neuropsychiatric assessment

If you are found to be eligible for surgery, you will be referred for a neuropsychiatric assessment with Consultant Neuropsychiatrist, Dr Tomasz Bajorek. This will involve an assessment of your expectations and understanding of surgery. It will also explore your current wellbeing.

Outcomes of the assessment

The results of all of the tests are considered collectively by the team. This is a complex process and all of the information is considered to make an informed decision about your care. The assessment process will identify the specific risks to you and the chance of a successful surgery.

There are three potential outcomes of the assessment:

Oxford Epilepsy Surgery Pathway (pdf, 368 KB)