Epilepsy surgery is a specialized medical procedure aimed at controlling or eliminating seizures in patients whose condition has not responded to medication. The primary goal is to achieve seizure freedom or significantly reduce seizure frequency and severity to improve the patient’s quality of life. This treatment is reserved for individuals whose epilepsy is classified as drug-resistant, meaning standard anti-seizure medications have proven ineffective.
A diagnosis of drug-resistant epilepsy indicates that a person has failed to achieve sustained seizure freedom after adequate trials of two appropriately chosen and tolerated anti-seizure drug regimens. Once the first two medications fail, the probability of achieving seizure control with any subsequent drug drops to less than five percent. Surgery is considered a treatment option for those who have exhausted pharmacological options and continue to experience disabling seizures.
Eligibility and Initial Screening
Candidacy begins with a comprehensive review of the patient’s medical history by a multidisciplinary epilepsy team, including an epileptologist, neurosurgeon, and neuropsychologist. This initial screening confirms the drug-resistant nature of the epilepsy and ensures the patient is experiencing seizures that significantly impair their daily life.
A second prerequisite is that the seizures originate from a single, definable area of the brain, known as the seizure focus. Surgery is most effective when this area can be precisely identified and safely addressed. Patients whose seizures originate from multiple locations or whose epilepsy is generalized are typically not candidates for resective surgical approaches.
The decision to pursue a surgical evaluation identifies potential candidates who may benefit from extensive testing. The initial clinical assessment, combined with routine brain imaging and electroencephalogram (EEG) results, determines if a surgically treatable syndrome is likely. The pre-surgical evaluation allows the team to gather necessary data to determine the risk-to-benefit ratio.
Comprehensive Pre-Surgical Evaluation
Once eligible, the patient enters a rigorous evaluation phase designed to pinpoint the seizure focus and map the brain’s functional areas. Video-EEG monitoring is a cornerstone, where the patient is hospitalized and monitored continuously with video recording and scalp electrodes to capture and analyze typical seizures. This provides detailed information about seizure manifestations and correlates them with electrical activity.
High-resolution Magnetic Resonance Imaging (MRI) identifies structural abnormalities, such as tumors or malformations, causing the seizures. Functional imaging studies further localize the focus. Positron Emission Tomography (PET) scans assess metabolism by detecting decreased glucose uptake between seizures. Single-Photon Emission Computed Tomography (SPECT) measures blood flow during a seizure to highlight the area of origin.
Neuropsychological testing establishes a baseline of the patient’s memory, language, and cognitive functions before intervention. This helps the team predict potential post-operative changes and identify the side of the brain that controls language and memory.
If non-invasive tests do not provide a clear seizure focus, or if the focus is near areas controlling movement or speech, invasive monitoring may be necessary. This involves placing electrodes directly on or within the brain for precise electrical readings. Techniques like Stereo-EEG (sEEG) use thin electrodes inserted deep into structures, while subdural grid electrodes are placed on the surface. These methods map the seizure onset zone with accuracy and confirm that removing the area will not cause unacceptable functional deficits before the surgical treatment plan is finalized.
Primary Types of Epilepsy Procedures
Surgical interventions for epilepsy fall into three main categories: resective, disconnective, and neuromodulatory procedures. Resective surgery is the most common type, involving physically removing the portion of the brain generating the seizures. This procedure is performed when the seizure focus is precisely located and can be removed without causing significant neurological impairment.
The most frequently performed resective procedure is a temporal lobectomy, which removes the seizure-generating area in the temporal lobe, often resulting in high rates of seizure freedom. Laser Interstitial Thermal Therapy (LITT) is a less invasive resective technique that uses an MRI-guided laser fiber to thermally ablate a small, well-defined seizure focus. The goal is complete seizure cessation by eliminating the source of abnormal electrical activity.
Disconnective procedures prevent the spread of seizure activity rather than removing brain tissue. A corpus callosotomy involves cutting the corpus callosum, the main bundle of fibers connecting the two hemispheres. This is often used for patients with drop seizures, preventing the seizure from spreading rapidly and causing a fall. Hemispherectomy or hemispherotomy involves surgically disconnecting or removing most of one hemisphere and is reserved for children with catastrophic, whole-hemisphere epilepsy.
The third category is neuromodulation, which involves implanting devices to regulate brain activity. Vagus Nerve Stimulation (VNS) involves a small generator implanted in the chest that sends regular electrical pulses to the vagus nerve, modulating brain activity to reduce seizure frequency. Responsive Neurostimulation (RNS) is a device implanted under the skull that constantly monitors brain activity via leads placed at the seizure focus, delivering a brief electrical pulse when a seizure begins. Deep Brain Stimulation (DBS) involves placing electrodes deep within specific brain structures and delivers continuous programmed stimulation to help control seizures.
Post-Surgical Care and Monitoring
Following epilepsy surgery, patients typically spend several days in the hospital for monitoring, often beginning in an intensive care unit. Common, temporary post-operative effects include headaches, fatigue, and swelling, managed with medication. The hospital stay allows the medical team to observe the patient for complications and ensure initial recovery proceeds smoothly.
Longer-term recovery at home can take several weeks to a few months, depending on the procedure and the individual’s healing rate. Patients are advised to rest and gradually increase activity levels, with restrictions on heavy lifting for the initial period. Regular follow-up appointments with the neurosurgeon and epileptologist monitor the surgical site and seizure control.
A component of post-surgical management is the continuation of anti-seizure medication. Even if seizures stop immediately, medication is not abruptly discontinued because the brain needs time to heal and adjust. The medication is usually maintained at the pre-operative dose for one to two years before the medical team considers a gradual tapering, based on sustained seizure freedom. Success is measured by the reduction or elimination of seizures and the improvement in the patient’s memory, mood, and overall quality of life, assessed through repeat neuropsychological evaluations.