The term cerebral dysrhythmia it was used very frequently in the 60s of the 20th century to refer to the changes in the electroencephalogram that some patients presented, particularly those with epilepsy.
With the passing of time, the term fell into disuse to give way to new more specific and descriptive terms, since the word “dysrhythmia” was very general and nonspecific; even worse, in some cases baseline brain rhythm changes could occur on the EEG with no obvious clinical signs.
Thus, the term cerebral dysrhythmia was abandoned, which for decades was synonymous with an alteration of the cerebral base rhythm without clear clinical significance..
However, with the advent of new technologies, the broadening of the range of diagnoses and specific neurophysiological studies, the term cerebral dysrhythmia has been retaken to explain certain conditions, symptoms and even behaviors that to date were classified as "idiopathic" (without apparent cause).
This new boom in the term cerebral dysrhythmia has been echoed in the digital media, where there is abundant information about it, although it is not always of the best quality; On the other hand, there is still controversy among specialists about the relevance or not of using this term, which is not used routinely by a large part of the medical community.
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Cerebral dysrhythmia is a term that is applied to an abnormal tracing of the EEG, which consists of a change from the normal rhythm but with an inconsistent pattern.
This means that sometimes the basic brain rhythm may be normal while in others it may be altered..
The problem arises when dysrhythmia is correlated with clinical findings, since in many cases the abnormal tracing of the EEG is not associated with obvious clinical changes.
Likewise, it may be the case of people with obvious clinical symptoms and signs (such as a tonic-clonic seizure due to epilepsy) with a normal electroencephalogram, hence the use of the term remains controversial and is still under study if its application in diagnostic terms is adequate or not.
To understand a little more about what changes in the EEG tracing are about, it is pertinent to remember some basic concepts.
The electroencephalogram is a diagnostic method that appeared in the late 1920s. It consists of recording by means of electrodes placed on the scalp the electrical activity of the brain.
This study generates what is known as the base rhythm, which is composed of four main wave patterns:
- Alpha rhythm with waves that oscillate between 8 and 13 Hz
- Beta rhythm with waves that oscillate between 14 and 60 Hz
- Delta rhythm with waves that oscillate between 0 and 4 Hz
- Theta rhythm with waves that oscillate between 4 and 7 Hz
These patterns are recorded at rest, with the person awake and after a good night's sleep, it is common to expect a normal pattern even in patients with epilepsy or with some other disorder..
In order to induce the appearance of abnormal patterns in the electroencephalogram, once the basal activity of the brain is recorded, the patient is stimulated with various methods ranging from hyperventilation to visual stimulation with strobe lights, through sound stimuli.
The objective is to trigger the pathological brain pattern in order to reach a definitive diagnosis.
In most cases of epilepsy, cerebrovascular disease, or dementia, there are clearly defined patterns that allow a precise diagnosis to be made..
However, in a special group of patients there may be changes in the basal rhythm of the electroencephalogram that do not correspond to any of the previously defined diagnostic patterns, these being the patients labeled with "cerebral dysrhythmia".
The main problem in these cases is to determine to what extent the dysrhythmia is pathological or simply an incidental finding without any clinical significance, especially in asymptomatic patients..
The causes of cerebral dysrhythmia are not clearly identified, although some situations and conditions have been suggested in which these transient alterations of the cerebral base rhythm may occur. One of the most frequent is lack of sleep due to the consumption of certain psychoactive substances.
In this sense, the dilemma persists, since despite the causal association between sleep-dysrhythmia and psychoactive drugs-dysrhythmia, not all people with this type of abnormal trace on the EEG have symptoms.
What is known for sure is that for some reason the normal balance between the excitation and inhibition mechanisms of the brain's neural circuits is lost; Likewise, there are data that indicate that dysrhythmia is not always generalized and that, on the contrary, it can occur in specific territories of the brain without there being changes in other areas.
Although the term cerebral dysrhythmia is not associated with a particular disease, some clinical studies indicate that this type of abnormal EEG pattern can be seen more frequently in certain clinical conditions such as:
- Chronic cerebrovascular disease
- Use of medications and / or psychoactive drugs
- Certain types of dementia
- Epilepsy
Of all of them, epilepsy is the one that has been best studied and where most of the evidence obtained from well-structured clinical studies points to; however it is not the common epilepsy with tonic-clonic seizures, well known to all.
Generalized epilepsy has clinical and electroencephalographic characteristics that allow an almost unequivocal diagnosis..
However, epilepsy itself is not a single disease, but a wide range of conditions ranging from focal seizures (Little Mal) to generalized seizures..
In this sense, it has been hypothesized that cerebral dysrhythmias could be a particular type of epilepsy that affects areas of the brain not associated with movement or consciousness..
Thus, it has been postulated that cerebral dysrhythmia could be caused by “neurovegetative epilepsy”, where the affected area of the brain regulates autonomic functions, so the symptoms may not be clearly identifiable since they could be confused with a diarrheal or dyspeptic syndrome banal.
On the other hand, cerebral dysrhythmia has been associated with irascible and easily altered personalities; therefore the diagnosis fits with a series of psychiatric disorders that could find an explanation in these electroencephalogram alterations.
The truth is that the abnormal trace of the electroencephalogram known as cerebral dysrhythmia exists, its use is gaining strength and modern research in neurophysiology could open an unsuspected range of so far unknown diagnoses.
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