Wiktor Wise
Electrical stimulation for seizure induction is a procedure that is often employed in the treatment of epilepsy. It involves the use of electrodes to stimulate specific areas of the brain, inducing seizures and helping to identify the epileptogenic zone. While this technique has been successfully used in presurgical investigations, particularly in Europe, it remains controversial and non-standardized. The effectiveness of electrical stimulation in treating seizures depends on various factors, including the type of electrodes used, stimulation parameters, and the presence of after-discharge. High-frequency stimulation is generally more effective in inducing seizures but carries a higher risk of adverse effects and false positives. On the other hand, low-frequency electrical stimulation has been shown to suppress seizures and reduce their frequency and severity.
| Characteristics | Values |
|---|---|
| Purpose | To delineate epileptogenic cortex through induction of typical seizures, identify symptomatogenic zones, and determine the value of ES-induced seizures (ESIS) in epilepsy surgery |
| Effectiveness | Induction of ESIS occurs in 51.6–75.3% of stimulated patients |
| Adverse Effects | High-frequency stimulation is associated with a greater frequency of adverse effects and false positives |
| Precautions | ES should be performed with the patient fully medicated to avoid induction of atypical seizures |
| Stimulation Type | Both low- and high-frequency ES have been employed in studies |
| Procedure | The procedure for ES remains non-standardized and varies among centers |
| Brain Mapping | Brain mapping should delineate eloquent areas at the individual level due to variations in the language network |
| Functional Mapping | ES influences functional mapping, particularly in language mapping |
| Treatment | ES is used as a treatment for seizures, including responsive neurostimulation and deep brain stimulation |
| Outcome | About 60% of patients become seizure-free, 20% see a significant reduction, and the remaining see no improvement |
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What You'll Learn
- ES (electrical stimulation) is used to identify symptomatogenic zones
- ES helps delineate epileptogenic cortex through the induction of typical seizures
- ES is commonly performed during a presurgical investigation
- ES-induced seizures occur in 51.6–75.3% of stimulated patients
- ES should be performed with the patient fully medicated
ES (electrical stimulation) is used to identify symptomatogenic zones
Electrical stimulation (ES) is a technique that involves sending electrical currents through the skin and into muscles. It is used for various purposes, including physical therapy and epilepsy treatment. In the context of epilepsy surgery, ES is employed to identify the epileptogenic cortex, which is the area of the brain necessary for the generation of seizures. While ES is frequently used for this purpose, its value in epilepsy surgery remains a subject of debate among professionals.
ES is also used to identify symptomatogenic zones, and this application has seen greater success and has a more long-standing evidence base. The symptomatogenic zone refers to the area of the cortex that, when activated by an epileptiform discharge, produces ictal symptoms. By understanding this zone, medical professionals can better comprehend the epileptogenic zone and the seizure onset zone, aiding in the formulation of effective resection strategies.
Recent studies have indicated that stimulation of exclusively mesial temporal lobe structures can elicit central apnea, which is associated with symptomatogenic anatomic substrates of ictal central apnea (ICA). This finding contradicts traditional beliefs that mesial temporal ES is non-symptomatogenic. ES-induced apnea studies suggest that ICA is a crucial semiological feature in localizing the symptomatogenic zone to mesial temporal lobe structures, which must be considered in surgical planning and resection strategies.
ES-induced seizures (ESIS) have been extensively studied, with a meta-analysis of 530 patients showing a favourable outcome associated with ESIS prior to surgery. However, the stimulation methodology varies between centres, and there is limited evidence directly linking ESIS to surgical outcomes. The use of ES for seizure induction also varies in its approach and attitude between epilepsy centres.
In conclusion, while ES is a valuable tool for identifying symptomatogenic zones, there are some challenges and controversies surrounding its use. Standardization and further research are needed to optimize its application in epilepsy surgery and improve patient outcomes.
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ES helps delineate epileptogenic cortex through the induction of typical seizures
Electrical stimulation (ES) is a technique that has been developed to help identify the epileptogenic zone in the brain. The challenge in epilepsy surgery is to remove this epileptogenic zone without compromising postoperative function, and ES is used to identify it with greater anatomical and physiological precision.
ES involves the use of electrodes to stimulate the brain and induce seizures. The procedure is commonly performed during a presurgical investigation to map eloquent areas of the brain that are essential to language and motor function. However, it is not yet standardized among centres, and differences in equipment and methods should be considered when comparing results from different series.
The use of ES to induce seizures and aid in the delineation of the epileptogenic cortex is a highly promising tool. Studies have shown that ES-induced seizures (ESIS) are associated with favourable postoperative outcomes. Cuello Oderiz et al. found that in the group with favourable outcomes, the percentage of ESIS was greater, and the number of resected electrode contacts where stimulation induced seizures was higher, indicating that ESIS could be an indicator of the epileptogenic zone.
Furthermore, ES-induced ictal central apnea (ICA) is also a relevant sign when localizing the symptomatogenic zone for epilepsy surgery. Central apnea is a likely result of seizure activity and may be reproduced by ES of the mesial temporal structures, especially the amygdala. ES-induced ICA can be the first and sometimes the only semiological phenomenon, allowing for the potential delineation of the patient's symptomatogenic and ictal onset zones and, consequently, the putative epileptogenic zone.
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ES is commonly performed during a presurgical investigation
Electrical stimulation (ES) is a frequently employed method that potentially delineates the epileptogenic cortex through the induction of typical seizures. ES is also used to identify symptomatogenic zones, with a higher success rate and a long-standing evidence base. ES is commonly performed during a presurgical investigation to identify the epileptogenic zone and seizure propagation networks. The challenge in epilepsy surgery is to remove the epileptogenic zone without compromising the functional network. ES is used for triggering seizures and for functional mapping to answer the question of whether there is a spatio-temporal overlap between the epileptogenic and the functional network.
The procedure for ES varies between centers, and the net result may be difficult to predict due to various methodological and physiological factors. These factors include stimulation parameters, the type of electrodes used, tasks used, and the presence or absence of an after-discharge. For example, the use of subdural electrodes in combination with depth electrodes helps delineate seizure foci. Hybrid surface electrodes with microelectrodes interspersed between macroelectrodes are becoming popular due to their increased spatial resolution.
The stimulation parameters depend on the type of epilepsy being treated. For instance, the mesial temporal lobe is sensitive to low-frequency stimulation, while high-frequency stimulation is more effective in inducing seizures but is associated with a greater frequency of adverse effects and false positives. False positives refer to clinical events that are not acknowledged by the patient as typical and are not related to the anatomical site of ES. To avoid false positives and the induction of atypical seizures, ES should be performed with the patient fully medicated.
Recent studies have identified ictal central apnea (ICA) as a semiological sign in temporal lobe epilepsies, which can be elicited by ES and may be valuable in seizure analysis for presurgical assessments. ES-induced seizures may potentially replace spontaneous seizures during presurgical invasive evaluation.
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ES-induced seizures occur in 51.6–75.3% of stimulated patients
Electrical stimulation (ES) is a procedure that can be used to induce seizures in patients with epilepsy. It is often employed during epilepsy surgery to help identify the epileptogenic zone, or the area of the brain that is responsible for seizure activity. By inducing seizures, doctors can study the seizure's characteristics and make more informed decisions during surgery.
The success rate of ES-induced seizures is important because it can impact the surgical outcome for patients with epilepsy. A meta-analysis of studies with ES-induced seizures found that a favourable outcome was associated with ES-induced seizures prior to surgery. This suggests that the induction of seizures through ES can help improve surgical outcomes and is, therefore, a valuable tool in the presurgical investigation of epilepsy.
However, it is important to note that the procedure is not without risks. High-frequency stimulation, for example, has been associated with a greater frequency of adverse effects and false positives. False positives refer to clinical events that are not typical seizures and are not related to the anatomical site of ES. To minimise the risk of false positives, ES should be performed with the patient fully medicated.
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ES should be performed with the patient fully medicated
Electrical stimulation (ES) is a frequently employed method that potentially identifies the epileptogenic cortex through the induction of typical seizures. Despite its common usage, its value for epilepsy surgery remains controversial. ES is also used to identify symptomatogenic zones with greater success and a long-standing evidence base. ES-induced seizures (ESIS) occur in 51.6–75.3% of stimulated patients.
To avoid false positives, ES is started at 1 Hz and, if no seizures are elicited, the frequency parameters are progressively increased to 5, 20, and 50 Hz sequentially. This progressive increase in frequency allows for a controlled environment in which the effects of ES can be studied without inducing atypical seizures.
The procedure for ES remains non-standardized among centers, and differences between grids and intracerebral depth electrodes should be considered when comparing results from different series. Brain mapping, for example, should delineate eloquent areas at the individual level as the language network varies among patients.
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Frequently asked questions
Electrical stimulation is a non-invasive procedure that has been shown to reduce seizures in patients. However, it is important to note that the procedure may vary depending on the patient and the type of epilepsy they are experiencing. While it is generally well-tolerated, some patients may experience adverse effects such as breathing dysfunction.
Electrical stimulation (ES) is a procedure that uses electrical currents to stimulate the brain and induce seizures. ES is often used to delineate the epileptogenic cortex and identify symptomatogenic zones.
The electrical stimulation procedure involves the application of electrical currents to the brain, specifically the epileptogenic zone, to induce seizures. The type of electrodes used, the stimulation parameters, and the tasks used can vary depending on the patient and the center performing the procedure.
Electrical stimulation is a valuable tool for epilepsy surgery as it helps to identify the epileptogenic zone and the symptomatogenic zones. It also aids in understanding the underlying pathology of seizures and can be used to develop novel treatment options for patients who cannot undergo surgery or have neurosurgical complications.
While electrical stimulation is generally safe, there are some risks associated with the procedure. These include adverse effects such as breathing dysfunction and false positives, where the patient experiences clinical events that are not typical seizures. It is important that ES is performed with the patient fully medicated to avoid the induction of atypical seizures.
