Diagnostic Tests
- Introduction
- Electroencephalography
- Brain Imaging
- Biochemical, Metabolic and Genetic testing
- To Arrange a Test
Special tests are performed in some children with epilepsy and related seizure disorders. The need for tests is determined by the detailed clinical assessment of a practitioner experienced in child health issues. Tests are generally performed to confirm a clinical suspicion, determine the type of seizure or epilepsy, determine the underlying cause of a child's epilepsy, assess the severity or monitor treatment of a child's epilepsy, assess associated medical or psychological problems, or determine the most appropriate treatment of a child's condition. Tests are not performed to determine if a child has epilepsy or not.
Children who present to their doctor or an emergency department with a major seizure episode will usually have a blood test to check the sugar, calcium, magnesium and salt levels, as abnormalities of the body chemistry can lead to seizures. In a child with epileptic seizures, a recording of brainwave activity (EEG) and a picture of the brain may be obtained, where necessary. In special circumstances, some children with seizures may have an examination of the spinal fluid (lumbar puncture), metabolic testing of the blood or urine, or genetic tests such as an examination of the chromosomes. Children with uncontrolled epilepsy sometimes undergo detailed EEG and imaging studies as an inpatient and outpatient to accurately localise the source and determine the cause of their seizures, with a view to specialised treatments.
Electroencephalography
Electroencephalography (EEG) is a test by which the electrical activity generated by the brain is recorded through thin wires placed on the scalp. Normal brain rhythms and any abnormal epileptic activity are reviewed on a computer screen or on paper. The EEG recording assists the neurologist or paediatrician in determination of a child's seizure type and epilepsy syndrome. In special circumstances, EEG may assist monitoring of treatment and help localise the seizure focus. In children with suspected seizure disorders, EEG should be recorded and interpreted in a centre experienced in childhood epilepsies and EEG.
Brain Imaging
Brain imaging is not performed routinely in children with epilepsy, as the majority of children with seizures have idiopathic disorders with normal brains. Structural imaging (CT and MRI) is performed when there is suspicion or the need to exclude an underlying brain abnormality eg. scar, malformation, tumour, infection etc. Functional imaging (SPECT, PET and MRI) is performed only in special circumstances to assist localisation of a seizure focus and its relationship to important brain regions, usually in children being considered for epilepsy surgery.
computerised tomography (CT)
- magnetic resonance imaging (MRI)
- single-photon emission computerised tomography (SPECT)
- positron emission tomography (PET)
Biochemical, Metabolic and Genetic testing
Most children with new-onset seizures will have a blood test to exclude low blood sugar or blood salt (sodium, calcium, magnesium) levels as the cause of their seizures. Infants and young children with epilepsy of unknown cause may undergo more complex blood, urine and spinal fluid testing to look for a possible biochemical or genetic basis, especially when seizures are accompanied by delayed development and there is the impression of a deterioration in seizure control.
Although the majority of childhood epilepsies have a genetic (familial) component, like other common medical problems (eg. asthma, migraine, diabetes), there is as yet no specific tests to identify these factors. Chromosome tests may be performed in children with epilepsy and delayed development, but it is rare to identify an abnormality with such tests.
To Arrange a Test
Speak to your doctor about the appropriateness of any special tests, such as EEG monitoring or brain scanning. You will need a referral letter from your family doctor, paediatrician or neurologist to have such tests.
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| Referring doctors click to download EEG request form |
Routine EEG can be organised by you or your doctor by contacting the EEG Department on 9345 5661 to make the appointment. The referring doctor needs to provide you with, or send in, a referal letter or request card. Please don't forget to bring along your Medicare card.
Video EEG monitoring is a specialised service that requires neurologist evaluation of patient suitability and the type and duration of monitoring. This is usually done after a CEP neurologist sees a patient in the clinic, or occasionally after talking to the referring doctor. Much planning is required prior to video-EEG monitoring.
Imaging tests (brain scans) such as CT and MRI are performed by the Medical Imaging (Radiology) department.