Epilepsy surgery is occasionally recommended and offered for specific patients with poorly-controlled recurring seizures. Generally performed by neurosurgeons, these various forms of surgical epilepsy treatment are tailored to each patient depending on their specific type and cause of epilepsy.
Which Epilepsy Patients are Generally Treated by Epilepsy Surgery?
- Patients Who Failed Medical Treatment: Patients with epilepsy who fail treatment with anti-seizure medications may be considered for epilepsy surgery treatment. The primary treatment for patients with a new diagnosis of epilepsy is generally medication for the majority of types of epilepsy. Most patients will respond to medications with reduced frequency of their seizures or complete seizure control. However, if after an appropriate trial of various medications and/or combinations of medications a patient still has poor seizure control surgical options may be explored. This decision is generally made by the treating neurologists and neurosurgeons and is based on several factors including the severity and frequency of seizures and cause of the epilepsy. In general, surgery is considered more strongly and is more effective if a specific focal area of disease can be identified in the brain. If no specific area of the brain can be identified where the seizures are originating treatment with surgery is more difficult, less likely to be effective and often contraindicated.
- Patients with a Surgical Disease: Some causes of epilepsy are primarily surgical in nature. For example, patients with some brain tumors or cerebrovascular diseases such as arteriovenous malformation or cavernous malformation may have seizures. Additionally, some causes of epilepsy such as cortical dysplasia and Sturge-Weber syndrome are classically very difficult to control with medication and are associated with a focal lesion in the brain which is easily identified in many patients. While many of these patients will initially be prescribed anti-seizure medications to help control their seizures, these diseases are often treated surgically as well. Removal of the offending lesion in the brain may help control the epilepsy in some cases.
What Types of Surgical Procedures are Performed for Epilepsy?
- Procedures to Identify the Seizure Focus: The seizure focus is the area in the brain from which seizures originate. Even seizures that quickly generalize to involve the whole brain often have a source where the seizures start. If this source can be identified, then theoretically removal of that focus can help control the seizures. While in some cases a discrete and obvious lesion in the brain can be identified on imaging (such as a brain MRI, it can be difficult to identify the focus or confirm that all the seizures are coming from one specific part of the brain. Because epilepsy surgery is much more effective when a seizure focus can be identified, great care is usually taken to identify this focus prior to considering surgery. Therefore, some preliminary procedures are used to identify and confirm the seizure focus.
Non-invasive testing is usually first performed in an attempt to identify the source of seizures. This can include many forms of tests and imaging including, but not limited to, MRI, EEG, PET scan, and magnetoencephalography (MEG).
If the seizure focus cannot be identified with these non-invasive techniques, some patients will have invasive monitoring. This means that an epilepsy surgery procedure is performed to help identify the focus. This can include implantation of electrodes on or in the brain which provide better electrical recordings from the brain during a seizure. Generally, these patients are then monitored in the hospital with continuous electrical recordings taken from these electrodes. When the patient experiences a seizure in the hospital the recordings from these electrodes can often be used to identify or confirm the source of the seizures. This information is then used to guide subsequent surgery to remove the identified focus, along with the electrodes.
In rare cases no seizure focus can be identified or there are multiple foci identified.
- Procedures to Remove the Seizure Focus: Once a surgical candidate has undergone testing to identify the source of their seizures and a definite source has been identified, they are considered for epilepsy surgery to remove that diseased part of the brain which is causing the seizures. The part of the brain removed varies depending on the specifics of each case. The goal is to completely remove the seizure focus and any surrounding diseased tissue to prevent future seizures. An example is a temporal lobectomy (removal of part of the temporal lobe) in treating temporal lobe epilepsy, which originates from the temporal lobe.
In rare cases where the seizure focus is very large and/or associated with a disease affecting a large portion of one hemisphere of the brain, a more extensive removal of brain tissue may be recommended. Some specialized centers perform hemispherectomy, removal and/or disconnection of one whole half of the brain (a hemisphere). For example, extensive cortical dysplasia, severe Sturge-Weber syndrome, hemimegalencephaly and Rasmussen's encephalitis may require this drastic epilepsy surgery approach to have the possibility to control seizures.
- Procedures to Limit the Spread of Seizures: In some rare cases, a discrete seizure focus cannot be identified despite invasive and non-invasive testing. If nothing else is possible to control the epilepsy, some surgical procedures can be considered to limit the severity of the seizures. For example, preventing seizures from spreading to the whole brain can help limit the severity of the seizures and therefore decrease the death and disability which can be associated with severe epilepsy. An example of this type of procedure is the corpus callosotomy. The corpus callosum is a large structure in the middle of the brain which is composed of white matter nerve fibers passing from one hemisphere to the other. It is how most parts of the cerebral cortex communicates with the other side to coordinate brain activity. If a seizure starts on one side of the brain it can often spread rapidly across this fiber bundle to involve the other side. By surgically cutting part of the corpus callosum the spread of the seizure activity can be halted, keeping the seizure on one side of the brain. This type of procedure does not eliminate the seizures, but may alter the consequences and type of seizure so that there is less clinical impact on the patient.
- Vagal Nerve Stimulator: For some specific patients who are not good surgical candidates because a seizure focus cannot be identified or who have failed other surgical treatment, implantation of a vagal nerve stimulator may be an epilepsy surgery treatment option. It has been found that in some forms of epilepsy, stimulation of the vagal nerve, a nerve that is an important part in the autonomic nervous system, may limit the occurrence of seizures. In this surgical procedure, an electrode is placed around the vagal nerve in the neck. This is connected to a generator which is implanted under the skin in the chest. The generator can be programed to various types of stimulation of the nerve. In general the vagal nerve stimulators do not eliminate seizures. However, in some patients they reduce the frequency or severity of seizures.
Each patient with epilepsy should consult their own treating physicians as to the recommended treatment options in their specific case.
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This site is not intended to offer medical advice. Every patient is different, and only your personal physician can help to counsel you about what is best for your situation. What we offer is general reference information about various disorders and treatments for your education.
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