Epilepsy: diagnosis

The most informative diagnostic method for epilepsy is a thorough history and detailed information on the manifestations of seizures. In physical and neurological examination, special attention should be paid to the identification of neurological symptoms that may indicate the etiology and localization of the epileptic focus. However, in epilepsy, the history is more important than physical examination.

Laboratory blood tests are performed to establish the infectious or biochemical causes of seizures, as well as baseline values of white and red blood, platelet count, function lists and kidneys before prescribing anti-epileptic drugs. Lumbar puncture may be required to rule out meningitis.

Structural changes in the brain that may cause epileptic seizures — for example, tumors, hematomas, cavernous angiomas, arteriovenous malformation, abscess, dysplasia, or long-standing stroke — may require a neuroimaging study. MRI is more informative in epileptic seizures than CT, as it can detect hidden structural changes, including mesotemporal sclerosis, which is manifested by atrophy of the hippocampus and an increase in the intensity of the signal from it on T2-weighted images.

Mesothemporal sclerosis (MTS) is often found in patients with temporal lobe epilepsy. In this regard, the question is widely debated - whether it is the cause or consequence of seizures. Although in laboratory animals, MTS develops after repeated temporal seizures, there are only a few human observations with MRI in dynamics, confirming the possibility of the appearance and development of MTS signs with repeated seizures. On the other hand, hypoxia and ischemia can cause changes in the hippocampus, similar to those observed in MTS, before seizures occur. In any case, MTS is a very useful neuroimaging marker of temporal epilepsy, which allows to establish the localization of the epileptic focus. This, however, cannot serve as evidence that all epileptic seizures in this patient are generated in this particular zone.

EEG has a particularly important diagnostic value in epilepsy. EEG is a registration of fluctuations in time of electric potentials between two points. Usually, the EEG is recorded using 8-32 pairs of electrodes placed over different parts of the head. Registration of electrical activity usually occurs within 15-30 minutes. Ideally, the EEG is desirable to record both during wakefulness and during sleep, since epileptic activity can only occur in a state of drowsiness or shallow sleep. Specialists in EEG interpret its data, paying attention to the total voltage, the symmetry of the activity of the relevant areas of the brain, the frequency spectrum, the presence of certain rhythms, for example, an alpha rhythm with a frequency of 8-12 / s in the back of the brain, the presence of focal or paroxysmal changes. Focal changes may be detected in the form of slow waves (for example, delta activity with a frequency of 0-3 / s or theta activity with a frequency of 4-7 / s) or in the form of a decrease in the EEG voltage. Paroxysmal activity may be manifested by the presence of peaks, sharp waves, peak-wave complexes, changes accompanying epileptic seizures.

Usually, an EEG is rarely possible to take off during a seizure. Therefore, in those cases where the seizure must be fixed to clarify the localization of the epileptic focus while planning an intervention, long-term EEG recording is necessary. Video and audio recordings can be synchronized with the EEG in order to reveal the correspondence between behavioral phenomena and electrical activity. In some cases, before surgical intervention, it is necessary to resort to invasive EEG recording using intracranial electrodes.

EEG data taken by themselves cannot serve as a basis for diagnosing epilepsy. EEG is only an additional study confirming the history data. It should be borne in mind that some individuals show pathological peaks on the EEG, but never seizures, and, therefore, they cannot be diagnosed with epilepsy. On the contrary, in patients with epilepsy in the interictal period, the EEG may be normal.

Imitation of epilepsy

Some states can manifest pathological movements, sensations, loss of reactivity, but they are not associated with a pathological electrical discharge in the brain. Thus, a syncope can be incorrectly regarded as an epileptic seizure, although in a typical case it is not accompanied by such a long period of seizures. A sharp decrease in brain perfusion can cause symptoms similar to epilepsy. Hypoglycemia or hypoxia can cause confusion, as with epileptic seizures, and in some patients there may be difficulties in the differential diagnosis of seizures with severe migraine attacks, accompanied by confusion. Transient global amnesia is manifested by a sudden and spontaneous loss of the ability to memorize new information. It can be distinguished from complex partial seizures by the duration (several hours) or by the integrity of all other cognitive functions. Sleep disturbances such as narcolepsy, cataplexy, or excessive daytime sleepiness may also resemble epileptic seizures. Extrapyramidal disorders, such as tremor, tics, dystonic postures, chorea, are sometimes mistaken for simple motor partial seizures.

[1], [2], [3]

Conditions that mimic epilepsy

There are many clinical pictures and classifications, but they cannot be considered satisfactory. In particular, it has been shown that schizophrenia is more common among patients with epilepsy than among patients with other chronic neurological disorders, such as migraine, for example. Theoretically, they can all be associated with the commission of crimes. The literature describes the following states:

1. Hallucinations and / or severe emotional disorders occurring due to a seizure: during aura or during one of the other disorders of consciousness.
2. Paranoid hallucinatory conditions after grand mal seizures, lasting two to three weeks and accompanied by stupefaction.
3. Transient schizophrenia-like episodes ending by themselves and observed between seizures. They can vary greatly from case to case: some patients fully retain a high degree of consciousness, while in others the consciousness is “clouded”. Some have amnesia, and some remember well. In some, abnormal EEG is noted, while in others, EEG normalizes (and becomes abnormal with the cessation of psychosis). Some effects are due to therapy.
4. Chronic schizophrenia-like psychosis, identical to paranoid schizophrenia. Described in connection with a long history of epilepsy (usually temporal), lasting more than 14 years.
5. Affective disorders. It seems that these disorders are more common in people with temporal epilepsy. They are usually short in time and complete by themselves. Affective and schizoaffective psychoses also occur. Nevertheless, it must be remembered that suicide rates are elevated among people with epilepsy.
6. Fainting
7. Sleep disorders (narcolepsy, cataplexy, excessive daytime sleepiness)
8. Ischemic attacks
9. Heart rhythm disorders
10. GIP
11. Fluke
12. Migraine attacks with confusion
13. Transit Global Amnesia
14. Vestibulopathy
15. Yeast hyperkinesis, tics, dystonia
16. Panic attacks
17. Non-epileptic seizures {psychogenic seizures, pseudo-seizures)

Psychogenic conditions are also difficult to distinguish from epileptic seizures. Such conditions include panic attacks, hyperventilation, episodic loss of control syndrome (rage attacks, intermittent explosive disorder), as well as psychogenic seizures, which can be especially difficult to distinguish from true epileptic seizures. In attacks of holding the breath (affective respiratory attacks), the child, in a state of anger or fright, holds his breath, turns blue, loses consciousness, after which twitching is possible. Night terrors are characterized by a sudden incomplete awakening from a state of sleep with a piercing cry and confusion. Although breath-holding bouts and nightly fears make parents wary, these are benign conditions. Psychogenic seizures are also called psychosomatic seizures, pseudo-seizures, or non-epileptic seizures. They are provoked by subconscious conflict. In most cases, a non-epileptic seizure is not a conscious simulation of a seizure, but a subconscious psychosomatic response to stress. Treatment of psychogenic seizures consists in psychological counseling and behavioral therapy, and not in the use of anti-epileptic drugs. Video electroencephalographic monitoring is usually necessary to confirm the diagnosis of psychogenic seizures, since the changes usually observed during an epileptic seizure are absent during psychogenic seizures. Since seizures that mimic epileptic seizures can be difficult to distinguish from true epileptic seizures, some patients who have mistakenly diagnosed epilepsy have been inadequately treated for many years by taking anti-epileptic drugs. Obtaining detailed information about the nature of the attack is key to the diagnosis of pseudo-fit. At the same time, special attention should be paid to the nature of the prodroma, stereotype, the duration of the attacks, the situation in which they arise, the provoking factors, the behavior of the patient during the attacks.

[4], [5], [6]