Introduction
If epilepsy is suspected, one should consult a neurologist for clarification. There are a number of diagnostic options available for the diagnosis of epilepsy. Other diseases that cause similar symptoms can also be excluded. For further treatment it is important to know what type of epilepsy it might be, so a careful examination of the brain and its functions is crucial.
Diagnostic procedures
For the diagnosis of epilepsy, the most important factors are anamnesis and the history of a stranger; it is helpful, for example, if an observer imitates the course of the seizure. Furthermore, an EEG (electroencephalogram) of the brain waves is written. Recording during sleep (sleep EEG), as long-term EEG or as provocation EEG is possible.
The latter refers to the attempted triggering of an epileptic seizure by means of a provocation method such as sleep deprivation, hyperventilation or light stimulation. Imaging techniques such as computer tomography (CT) or magnetic resonance imaging (MRI) are suitable for detecting or ruling out structural changes in the brain as the cause. Vascular malformations can be detected by means of angiography, a method of vascular imaging.
Furthermore, special examinations (SPECT = single photon emission computed tomography, PET = positron emission tomography) can be used to visualize blood circulation and metabolism. A blood sample can also provide diagnostic indications of the presence of epilepsy. The enzyme creatine kinase (CK) and the hormone prolactin, which are elevated in one-fifth of patients, can be determined.
Finally, further tests should be performed to exclude symptomatic causes, which should be ordered depending on the suspected and differential diagnosis. As a rule, the standard diagnostic tests for suspected epilepsy are an MRI and an EEG in addition to the medical history. If epilepsy is suspected, an MRI of the brain should be performed as standard, but especially in younger patients.
For this purpose, there should be clear symptoms of an epileptic seizure to avoid a possibly unnecessary examination. In the MRI of the brain, a causative change in the brain can be seen in many people with epilepsy. This structural change is also called a “lesion” and often occurs in characteristic regions, such as the temporal lobe.
The EEG, i.e. the electro-encephalogram, is a very important component in the diagnosis of epilepsy. Brain waves are measured and recorded at various points on the head. They reflect the activity of the brain’s nerve cells and have characteristic patterns for certain states of alertness.
These patterns are potentials that vary in intensity depending on whether one is asleep or awake. If an epilepsy is present, patterns that are also typical for epilepsy can often be present. These include, for example, so-called “spikes”, “sharp waves” and “spikes and waves”, which are merely a description of how the potentials are represented.
Depending on where these patterns are derived, conclusions can be drawn about the localization of the brain structures causing the epilepsy. In certain epilepsy syndromes these patterns can also occur in typical sequences. However, it should be noted that epilepsy can exist even without the detection of specific potentials and that, conversely, in rare cases specific potentials can be measured occasionally without epilepsy being present.
It is often difficult to find directly characteristic potentials when performing an EEG. There are many types of epilepsy and epilepsy synptoms, which occur mainly at night. Therefore, it may be useful to perform a sleep EEG for some affected persons.
This is usually performed in a so-called sleep laboratory. The electrodes are attached before sleeping and the EEG is recorded overnight. This can often be very helpful in the diagnosis of epilepsy.
In some cases it is not so easy to record certain potentials and patterns with an EEG, because nobody can predict when an epileptic seizure will occur. In addition, a reliable diagnosis of epilepsy cannot always be made quickly. For these cases, a long-term EEG measurement can be useful.
In this case, an EEG measurement is performed over a longer period of time, often for 24 hours. This allows a more representative statement to be made about the probability of an existing epilepsy.A SPECT examination, i.e. single photon emission computed tomography, can be a helpful diagnostic tool for some patients. This is the case, for example, in epilepsy confirmed by symptoms, i.e. clinically, without evidence of a causative lesion in the MRI.
SPECT can provide information about possible circulatory disorders in certain areas of the brain. This can be of particular importance if surgery is a possible treatment option. A PET examination, also known as positron emission tomography, shows metabolic processes in the brain.
The question is whether there are areas of the brain that have a decreased metabolism, i.e. hypometabolism, or an increased metabolism, i.e. hypermetabolism. These can be the cause of epilepsy and are not sufficiently shown in the MRI.
Furthermore, a PET examination before a possible operation can be very helpful. A blood count can have a supporting function in the diagnosis of epilepsy. Different values are examined.
It is useful to check the blood sugar level in order to detect a possible sugar crisis. A check of different electrolytes can also provide information about the cause. If an infection of the brain is suspected, a cerebrospinal fluid puncture should be performed.
Another characteristic value in the blood count is the so-called creatine kinase. This is elevated when muscles are more active and tensed. It therefore increases during an epileptic seizure with muscle twitches and reaches its maximum value approx. 6 hours after the epileptic seizure.