This page covers other tests used to help diagnose epilepsy and when and why they’re used.
These include blood tests, genetic testing and antibody testing for the rare condition autoimmune encephalitis, which can also cause seizures.
Blood tests
A range of blood tests can be carried out to check general health levels and to rule out other causes of seizures, such as low blood sugar levels or diabetes.
Usually, all blood tests related to epilepsy can be taken at the same time as tests for other conditions.
Genetic testing
Some types of epilepsy have a genetic cause. They are linked to changes (also known as ‘mutations’) in specific genes that you have inherited from your parents.
A child, young person or adult may be referred for genetic testing when:
- The epilepsy started in infants under two years of age
- There are other features suggesting a specific genetic epilepsy syndrome, e.g. Dravet syndrome
- There are other features such as:
- a learning disability
- autism spectrum disorder
- a structural abnormality in the body, e.g. dysmorphism or congenital malformation – a physical defect present from birth, affecting, for example, the face, limbs, bones, brain, heart, lungs, liver and intestinal tract
- unexplained deterioration in memory or cognitive abilities (the core skills our brains use to think, learn, remember and reason)
Before a referral for genetic testing for epilepsy is made, an epilepsy specialist should discuss the purpose of the test and the possible implications of results with the person with epilepsy and, when appropriate, their parents or carers.
Whole-genome sequencing
Children with epilepsy of unknown cause, which started between two and three years of age, may be referred for whole-genome sequencing (which is now available to people of all ages).
Unlike other genetic tests, which only look at a few genes, whole-genome sequencing looks at all of a person’s genes.
It does still, however, focus only on changes in the genes linked to a specific condition, in this case epilepsy.
The results of whole-genome sequencing can help to:
- Diagnose the specific type of epilepsy
- Decide on appropriate treatment
- Tell whether other members of a family may also have the condition
- Tell if a person could pass the condition on to their children
- Help decide whether other relatives should also be offered genetic testing
For further information on genetic testing: https://www.nhs.uk/conditions/genetic-and-genomic-testing/
Antibody testing for autoimmune encephalitis
If someone has new-onset epilepsy, they may be referred for antibody testing if it’s suspected they may have autoimmune encephalitis.
Autoimmune encephalitis is a rare type of brain inflammation where the body’s immune system attacks healthy tissues in the brain.
Symptoms can include:
- Seizures
- Altered mental states
- Hallucinations
- Sleep problems
- Loss of speech
People with autoimmune encephalitis can also have status epilepticus with encephalopathy (brain disease, disorder or damage affecting the brain’s structure or function).
