Depth electrode is used for surgical intervention in the brain for epilepsy disorder. With this procedure, a thin and flexible rod with multiple electrodes attached is temporarily implanted in the deep areas below the cerebral cortex. It can electrically stimulate precisely defined areas in a patient’s head. In this way, it becomes possible to reduce the severity and frequency of epileptic seizures. Likewise, under certain circumstances, it can be used to prepare for the removal of affected cell formations in the brain.
What is a depth electrode?
The depth electrode is used for surgical intervention in the brain for epilepsy disorder. Implantation of the depth electrode into the brain provides extremely precise information about the site of origin of the epileptic seizures. It is narrowed down with an accuracy of a few millimeters. At the same time, this neurosurgical procedure can provide a detailed and very reliable prediction of the intensity and characteristics of memory after any surgery. Thus, the risk of removing too many nerve cells in the brain during a resection is minimized. This is especially relevant if the focus of an epilepsy-prone area is located at a very short distance from brain areas responsible for memory or even language formation. Of course, all risks should also be weighed that could lead to disturbances in the mental and physical well-being, behavior and cognitive performance of the treated person. In addition to the depth electrode, so-called imaging techniques, such as magnetic resonance imaging (MRI) and functional MRI, are also very important in this regard. They provide information as to whether the so-called epileptogenic area (the seizure-producing brain area) has a focal structure. Only in this case can it be surgically removed. If the seizures originate from scattered cell groupings, surgical intervention is not helpful. In very dramatic cases of focal epilepsy, a complete hemisphere of the brain can be removed.
Forms, types, and types
Surgery has excellent capabilities and recognized treatment modalities for these procedures, which are located in highly specialized facilities. They are basically used when drug therapy for an epileptic disorder does not produce the hoped-for results. According to many estimates, around 30 percent of all patients with focal epilepsy, i.e., epilepsy with foci, cannot be completely seizure-free if they are treated exclusively with medication. This proportion is less than ten percent for non-operable forms of epilepsy. For these reasons, it is now only very rarely necessary to use a depth electrode. However, it has the decisive advantage of being able to derive an electroencephalogram (EEG) from very deep areas of the brain, which allows a spatial evaluation of possible changes. If surgical intervention is actually required to overcome epilepsy, the depth electrode can be used to clarify the corresponding risks for the patient.
Structure and mode of operation
Epilepsy is a chronic disease of the nervous system based on changes in the cellular structure of the brain. These changes can be discharged in epileptic seizures, which are accompanied by the typical twitching all over the body and the risk of suffocation. From a medical point of view, a fundamental distinction is made between a single epileptic seizure and the nerve-related clinical picture of epilepsy. The epileptic seizure occurs singularly and as a rule very rarely and only in an extremely small group of patients. It is caused by a disturbance of the nerve cells in the brain, or of the electrical and chemical signals they send to each other. A very large number of nerve cells discharge at the same time, which excessively irritates individual brain areas or the entire brain. This sudden impulse triggers the epileptic seizure. Causes for these occasional occurrences can be an abnormality in the brain, due to injury or inflammation, drastic hypoglycemia, sudden alcohol withdrawal, poisoning, or significant oxygen deprivation.
Medical and health benefits
Chronic epilepsy, unlike single seizures, is caused by a change in a person’s brain that has developed over time. In this context, the epileptic seizures occur repeatedly. It is a brain damage that may be passed on by heredity or may be newly acquired. We speak of focal epilepsy when the recurrent seizures have their focus in a localized area of the brain. A so-called generalized epilepsy, on the other hand, is characterized by seizures occurring in both hemispheres of the brain. In reality, acquired (symptomatic) epilepsy is far more common than inherited epilepsy. In this case, the brain is often affected before or during birth. If it develops later in life, it can be caused by brain inflammation, head injuries, ulcers and strokes. Depth electrodes for the treatment of chronic epilepsy are now being brought to bear in various areas of surgery. This can be curative (curative) or causative (causal). An application of the depth electrode will eventually lead to the decision whether the affected cell area in the brain will be eliminated in the resective procedure, or whether such an intervention is not indicated. In resection, the brain region from which the epileptic seizures originate is cut out completely. The depth electrode can be used to determine exactly whether the correct area in the brain has been removed. If the epileptogenic focus is in the temporal lobe area, i.e., not in the particularly sensitive central and deep areas of the brain, removal of the damaged cell formation can completely eliminate all epileptic seizures in about 60 percent of these cases.