Diagnosis of epilepsy
introduction
If epilepsy is suspected, a neurologist should be consulted for clarification. A number of diagnostic options are available to diagnose 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
The most important factors for diagnosing epilepsy are medical history and external history; It is helpful, for example, if an observer imitates the course of the seizure.
Furthermore, an EEG (Electoencephalogram) written of brain waves. It is possible to record during sleep (sleep EEG), as a long-term EEG or as a provocation EEG.
The latter is the attempted triggering of an epileptic seizure using a provocation method such as sleep deprivation, hyperventilation or light stimulation.
Imaging methods such as a computed tomogram (CT) or a magnetic resonance tomogram are suitable to detect or rule out a structural change in the brain as the cause. Vascular malformations can be documented by means of angiography, a method for vascular imaging.
Furthermore, special examinations (SPECT = single-photon emission computed tomography, PET = positron emission tomography) can be used to show the blood flow and metabolism.
A blood sample can also provide diagnostic information about the presence of epilepsy. The determination of the enzyme creatine kinase (CK) and the hormone prolactin, which are elevated in a fifth of patients, are useful here.
Finally, further examinations should be carried out to exclude symptomatic causes, which should be arranged depending on the suspected and differential diagnosis.
If epilepsy is suspected, an MRI and an EEG are used as standard diagnostics in addition to the medical history.
Read more on the topic: Epilepsy
MRI of the brain
If epilepsy is suspected, an MRI of the brain should be done as standard, but especially in younger people. For this, there should be clear symptoms of an epileptic seizure in order to avoid a possibly unnecessary examination. In many people with epilepsy, a causal change in the brain can be seen in the MRI of the brain. This structural change is also known as a "lesion" and often occurs in characteristic regions such as the temporal lobe.
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EEG
The EEG, i.e. the electro-encephalogram, is a very important component in the diagnosis of epilepsy. Here, brain waves are measured and derived at various points on the head. They reflect the activity of the nerve cells in the brain and have characteristic patterns for certain wakefulness states. These patterns are potentials that vary in height depending on whether one is asleep or awake.
If epilepsy is present, patterns typical for epilepsy can often also be present. These include, for example, so-called “spikes”, “sharp waves” and “spikes and waves”, which are only a description of the representation of the potentials. Depending on the point at which these patterns are derived, conclusions can be drawn about the localization of the causative brain structures. In certain epilepsy syndromes, these patterns can also appear in typical sequences.
However, it should be noted that epilepsy can also be present without evidence of specific potentials and that conversely, in rare cases, specific potentials can be measured in isolated cases without epilepsy being present.
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Sleep EEG
It is often difficult to find characteristic potentials directly when performing an EEG. There are many types of epilepsy and epilepsy symptoms that occur mainly at night.
Therefore, it can make sense to perform a sleep EEG for some people affected. This is usually carried out in a so-called sleep laboratory. The electrodes are attached before going to sleep and the EEG is recorded overnight. This can often be very helpful in diagnosing epilepsy.
Long-term EEG
In some cases it is not so easy to record certain potentials and patterns with an EEG because no one can predict when an epileptic seizure will occur. In addition, a reliable diagnosis of epilepsy cannot always be made quickly. In these cases, a long-term EEG measurement can be useful. An EEG measurement is carried out 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.
SPECT
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 the case of epilepsy confirmed by the 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 particularly important when surgery is an option.
PET
A PET examination, also known as positron emission tomography, shows metabolic processes in the brain. The question arises as to whether there are areas in the brain that have a reduced metabolism, i.e. hypometabolism, or an increased metabolism, i.e. hypermetabolism.
These can be the cause of epilepsy and are not adequately represented in the MRI. Furthermore, a PET examination can be very helpful before a possible operation.
Read more on the topic: Positron emission tomography
Blood count
A blood count can have a supporting function in the diagnosis of epilepsy. Various values are examined here. It is useful to check your blood sugar in order to identify a possible causative sugar crisis. A check of various electrolytes can also provide information about the cause. If an infection of the brain is suspected, a CSF puncture should be performed.
Another characteristic value in the blood count is the so-called creatine kinase. This is higher with increased activity and tension of muscles. Therefore, it increases during an epileptic attack with muscle twitching and reaches its maximum value approx. 6 hours after the epileptic attack.
