Epilepsy Surgery: An Effective Solution for Patients with Drug-Resistant Epilepsy

Drug-resistant epilepsy is a major challenge in neurology when medical treatments are no longer effective. In this context, epilepsy surgery emerges as a key solution, opening a door of hope for many patients by helping control seizures and improving their quality of life [1]. Surgery is not only a high-tech procedure but also a crucial milestone in managing drug-resistant epilepsy, particularly at specialized centers such as University Hospital HCMC (UMC).

1. What is Drug-Resistant Epilepsy?

1.1. Definition

Drug-Resistant Epilepsy (DRE) is defined by the International League Against Epilepsy (ILAE) as the failure of adequate trials of two tolerated and appropriately chosen and used antiepileptic drug (AED) schedules (whether as monotherapies or in combination) to achieve sustained seizure freedom [1].

1.2. Prevalence

Among all patients with epilepsy, approximately 20% to 30% will develop drug-resistant epilepsy [2]. This is a concerning public health issue, leading to increased morbidity and mortality associated with seizures [1].

2. When Should Epilepsy Surgery Be Considered?

Epilepsy surgery is considered when medical treatments fail to control seizures, typically after attempting at least two appropriate antiepileptic medications [2]. The goals of surgery are to reduce the frequency and severity of seizures, avoid postoperative side effects, and improve quality of life [1].

2.1. Indication Criteria

The primary criteria for surgical indication include:

• Drug-resistant epilepsy: The patient fails to respond to at least two antiepileptic drugs [2].

• Severe impairment in quality of life: Seizures significantly impact the patient's daily living, education, employment, and social activities.

2.2. Preoperative Evaluation Process

The preoperative evaluation process is vital to identifying suitable candidates and selecting the optimal surgical approach. This process involves a series of in-depth tests and assessments [2]:

• Clinical Evaluation: Medical history, seizure types, frequency, and severity.

• Electroencephalogram (EEG): Records brain electrical activity to identify the seizure onset zone.

• Video-EEG Monitoring: Simultaneous long-term video and EEG recording to capture seizures and related electrical activity.

• Brain Magnetic Resonance Imaging (MRI): Detects brain structural abnormalities that may cause epilepsy, such as hippocampal sclerosis, brain tumors, or cortical malformations [2].

• Positron Emission Tomography (PET) or Single-Photon Emission Computed Tomography (SPECT): Evaluates metabolic disorders or cerebral blood flow to help localize the epileptogenic zone [2].

• Neuropsychological Assessment: Assesses the patient's language, memory, and cognitive functions.

• Wada Test: Evaluates the language and memory functions of each cerebral hemisphere to safeguard these functions during surgery [2].

• Invasive EEG Monitoring (Stereo-EEG / Subdural EEG Monitoring): When non-invasive tests do not clearly identify the seizure onset zone, electrodes may be placed directly into the brain for more precise electrical recording [2].

• Multidisciplinary Team (MDT) Consultation: A team consisting of epileptologists, neurosurgeons, neuroradiologists, and neuropsychologists reviews all findings to determine the best treatment plan [2].

3. Surgical Methods for Treating Drug-Resistant Epilepsy

Epilepsy surgery methods are categorized into various types, depending on the location and nature of the epileptogenic zone.

3.1. Resective Surgery

Resective surgery is the most common approach, aiming to remove the brain tissue responsible for seizures.

Temporal Lobe Surgery

This is the most prevalent type of surgery for drug-resistant epilepsy, particularly Temporal Lobe Epilepsy (TLE) [1].

• Anterior Temporal Lobectomy (ATL): Involves the removal of a portion of the temporal lobe, including the hippocampus and amygdala. The 5-year seizure-free rate post-surgery can reach up to 52% [1]. This method is significantly more effective than medical therapy for temporal lobe epilepsy [1].

• Selective Amygdalohippocampectomy (SAH): This procedure removes only the amygdala and hippocampus while preserving the lateral temporal neocortex. SAH is favored in many centers due to better brain tissue preservation and potentially more favorable neuropsychological outcomes, while offering seizure control efficacy comparable to ATL [4].

Extratemporal Resective Surgery

This surgery is applied when the epileptogenic zone is located outside the temporal lobe, typically in the frontal, parietal, or occipital lobes [2]. The efficacy of extratemporal surgery has been demonstrated through long-term follow-up studies [5]. However, it is more complex and has a lower success rate compared to temporal lobe surgery, especially in children [6].

Hemispherectomy

Hemispherectomy is a radical surgery that removes nearly an entire cerebral hemisphere or disconnects its function. This procedure is usually indicated for severe epilepsy cases in children involving widespread damage to one hemisphere that fails to respond to other treatments, such as hemiconvulsions-hemiplegia-epilepsy syndrome, perinatal injuries, unilateral brain malformations, Rasmussen's syndrome, or Sturge-Weber syndrome [1]. Approximately 77% of patients can achieve seizure freedom (Engel Class I) following surgery [1].

3.2. Palliative Surgery

Palliative surgery does not aim to completely cure epilepsy but rather to reduce the frequency and severity of seizures, particularly drop attacks or generalized spreading seizures.

Corpus Callosotomy

Involves cutting part or all of the corpus callosum (the bridge connecting the two brain hemispheres) to prevent the spread of seizures from one hemisphere to the other. It is usually indicated for patients with secondary generalized seizures, Lennox-Gastaut syndrome, or drop attacks [1]. This surgery can significantly reduce seizures, particularly drop attacks [1]. However, it carries specific risks, including disconnection syndrome, temporary or permanent motor deficits, and memory and language impairment [1].

Multiple Subpial Transection (MST)

A surgical technique where small horizontal cuts are made beneath the pia mater to disrupt horizontal propagation pathways of epileptic electrical activity while preserving vertical functional columns of the cerebral cortex. This method is used when the epileptogenic zone is located in vital functional brain regions (e.g., language, visual, or motor areas) that cannot be completely resected [1]. MST helps preserve function while controlling seizures, with approximately 79% of patients experiencing at least a 50% reduction in seizure frequency [1].

3.3. Neurostimulation

Neurostimulation methods involve implanting devices to modulate the electrical activity of the brain or related nerves.

Vagus Nerve Stimulation (VNS)

An adjunctive treatment for drug-resistant epilepsy, approved by the US FDA in 1997 [1]. A pulse generator is implanted subcutaneously in the left chest, with an electrode connected to the left vagus nerve in the neck. The device delivers regular electrical pulses to modulate brain electrical activity and reduce seizure frequency [1]. VNS can reduce seizure frequency by more than 50% in many patients [1]. Side effects are generally mild, primarily hoarseness and coughing [1].

Deep Brain Stimulation (DBS)

Involves implanting electrodes into deep brain structures (e.g., the anterior nucleus of the thalamus) and connecting them to a subcutaneous pulse generator. Electrical pulses are delivered continuously to modulate neural circuits involved in epilepsy [1]. DBS has been shown to reduce seizure frequency and improve quality of life in drug-resistant epilepsy patients [1]. However, the exact mechanism remains not fully understood [2].

Responsive Neurostimulation (RNS)

An implantable system capable of continuously monitoring brain electrical activity. When abnormal electrical activity likely to lead to a seizure is detected, the device delivers a small electrical pulse to abort the seizure before it spreads or starts [2]. Approved by the US FDA in 2013, RNS has demonstrated significant seizure reduction and quality of life improvements [2].

3.4. Other Surgical Interventions

Stereotactic Radiosurgery

A non-invasive treatment using highly focused radiation beams to destroy or modulate the epileptogenic brain zone without open surgery. It is typically used for epilepsy caused by deep lesions or those difficult to access via conventional surgery [1]. Its advantage is being non-invasive and avoiding open surgery risks, though therapeutic effects may take longer to manifest [1].

Magnetic Resonance-guided Laser Interstitial Thermal Therapy (MRgLITT)

A minimally invasive technique utilizing a laser fiber to generate heat and destroy epileptic brain tissue. The procedure is monitored via real-time MRI to ensure precision and safety, avoiding damage to surrounding tissues [2]. MRgLITT is a novel option for drug-resistant epilepsy cases that are difficult to reach via open surgery, offering fewer complications and shorter hospital stays [2].

4. Benefits of Epilepsy Surgery

Epilepsy surgery provides significant benefits for patients with drug-resistant epilepsy.

4.1. Seizure Control

The primary benefit is the ability to control or eliminate seizures. Studies show that temporal lobe surgery can render 58% of patients seizure-free, compared to only 8% in the medical therapy group [1]. Another study of 621 patients with drug-resistant TLE found that 73.6% achieved freedom from debilitating seizures (Engel Class I) post-surgery, a rate sustained at 65% after over 20 years of follow-up [3]. For extratemporal surgery, complete seizure freedom can reach up to 75% in carefully selected patients [6].

4.2. Improved Quality of Life

Controlling seizures helps patients avoid related dangers and substantially enhances their quality of life [1]. Patients can return to school, work, and social activities, experience reduced anxiety and depression, and enjoy improved cognitive functions [1]. Studies demonstrate that epilepsy surgery yields notable quality of life improvements, including psychosocial functioning [1].

5. Potential Risks and Complications

Despite its numerous benefits, epilepsy surgery entails certain risks and complications that require careful consideration.

5.1. General Complications

General risks associated with brain surgery include:

• Intracranial hemorrhage: Can occur during or after surgery [1].

• Infection: Surgical site infection, meningitis, or intracranial infection [1].

• Anesthesia reactions: Allergic responses or respiratory/cardiovascular complications.

• Neurological deficits: Impairment of functions related to the surgical site, such as motor, sensory, visual, or language functions.

5.2. Procedure-Specific Complications

Each type of surgery may be accompanied by specific complications:

• Resective Surgery

  • Neurological decline: Depending on the resected brain region, patients may experience visual field deficits ( hemianopia ), mild hemiparesis, language impairment, or memory decline [1]. Left temporal lobe surgery (dominant language hemisphere) may cause verbal memory deficits, while right temporal lobe surgery may affect spatial memory [4]. However, in children, cognitive recovery potential is generally superior to adults due to neuroplasticity [4].

  • Seizure recurrence: Although surgery aims for seizure control, recurrence remains possible, particularly if the epileptogenic zone is incompletely removed or if multifocal zones exist [4].

• Corpus Callosotomy:

  • Disconnection syndrome: Can cause symptoms such as difficulty coordinating both sides of the body, language disorders, or memory disturbances [1].

• Neurostimulation:

  • Device-related side effects: VNS may cause hoarseness and coughing. DBS and RNS carry risks of infection, hemorrhage, or device malfunction [1].

• MRgLITT:

  • New neurological deficits: May cause motor deficits, cognitive impairment, or vision issues, though usually temporary [2].

6. The Importance of Choosing a Specialized Center

Selecting a specialized epilepsy center plays a pivotal role in ensuring optimal treatment outcomes for drug-resistant epilepsy patients.

6.1. Expert Team

A specialized center features an experienced multidisciplinary team comprising epileptologists, neurosurgeons, neuroradiologists, neuropsychologists, and specialized technicians. Close collaboration among these experts ensures accurate diagnoses, personalized treatment planning, and safe, effective surgical execution [2].

6.2. Modern Equipment

Specialized centers are equipped with the most advanced diagnostic and therapeutic technologies, such as Video-EEG monitoring systems, 3T MRI, PET/SPECT, MEG, and modern surgical techniques like MRgLITT. These technologies facilitate precise localization of the epileptogenic zone, minimize damage to healthy brain tissue, and optimize surgical outcomes [2].

7. Frequently Asked Questions (FAQ)

• Does epilepsy surgery completely cure the condition?

  Epilepsy surgery can help many patients achieve complete seizure freedom, especially resective surgery in the temporal lobe [1]. However, not all cases are completely cured; some patients may still require antiepileptic medications or experience seizure recurrence after a period of time [3].

• Who is a suitable candidate for epilepsy surgery?

  Suitable candidates are individuals with drug-resistant epilepsy who have tried and failed at least two antiepileptic drugs, and who have a clearly defined epileptogenic zone that can be resected without causing severe neurological functional impairment [2].

• How long is the recovery period after surgery?

• Recovery time varies depending on the type of surgery and the patient's health status. Typically, patients can be discharged within a few days to a week. Full recovery may take several weeks to months, during which patients may require physical therapy, speech therapy, or cognitive rehabilitation [2].

• What should be noted after epilepsy surgery? 

  Following surgery, patients must adhere to periodic follow-up appointments, continue taking antiepileptic drugs as prescribed by their doctor (dosages may be gradually tapered if the condition stabilizes), and monitor for abnormal signs. Psychological support and rehabilitation are also vital to help patients reintegrate into society [1].

8. References

• [1] Jiyao Sheng (2018). Drug-Resistant Epilepsy and Surgery. 

  https://pmc.ncbi.nlm.nih.gov/articles/PMC5771378/. Accessed: 2025-12-12.

• [2] Wei Shan (2021). Potential surgical therapies for drug‐resistant focal epilepsy. 

  https://pmc.ncbi.nlm.nih.gov/articles/PMC8339538/. Accessed: 2025-12-12.

• [3] Marina Teixeira Ramalho Pereira Dalio (2022). Long-Term Outcome of Temporal Lobe Epilepsy Surgery in 621 Patients With Hippocampal Sclerosis: Clinical and Surgical Prognostic Factors. https://pmc.ncbi.nlm.nih.gov/articles/PMC9084624/. Accessed: 2025-12-12.
• [4] Yun-Jin Lee (2013). Temporal lobe epilepsy surgery in children versus adults: from etiologies to outcomes. https://pmc.ncbi.nlm.nih.gov/articles/PMC3728445/. Accessed: 2025-12-12.
• [5] Alaa Eldin Elsharkawy (2008). Long-term outcome of extratemporal epilepsy surgery among 154 adult patients. https://pubmed.ncbi.nlm.nih.gov/18377245/. Accessed: 2025-12-12.
• [6] Alexandra Liava (2012). Individually tailored extratemporal epilepsy surgery in children: anatomo-electro-clinical features and outcome predictors in a population of 53 cases. https://pubmed.ncbi.nlm.nih.gov/22902651/. Accessed:2025-12-12.

The information above is for reference purposes only and is not intended as medical advice. Please contact your doctor for detailed medical consultation.