Neurosurgical procedures to treat epilepsy have been performed at HUCH since the beginning of the 1990s. Approximately 25 to 30 epilepsy surgeries are performed at HUCH every year. One-third of all epilepsy surgeries are on adult patients, while in two-thirds of the operations, the patient is a child.
In Finland, epilepsy surgery is performed at only two university hospitals – HUCH and Kuopio University Hospital. HUCH treats both adult and pediatric patients. The pediatric patients are referred to Helsinki from all over Finland.
Planning surgery and types of operations
Epilepsy surgery is considered when harmful epileptic seizures continue despite anti-epileptic drugs. In children, severe epilepsy may slow down normal development. In such cases, surgery may be considered relatively soon after the onset of the disease. However, not all patients with severe epilepsy benefit from epilepsy surgery.
Before surgery, the risks and possible benefits of surgery are carefully assessed. Various examinations and tests are planned and performed on case by case basis to determine the exact region in the brain where the seizures originate. Once localized, one has to estimate if that particular region can be completely removed without any major adverse effects such as e.g. speech or movement disability.
In surgery, the area causing epileptic seizures is removed, if possible. Sometimes this area is only a small portion of brain surface, while in other cases the area may comprise an entire hemisphere. In most cases, the part of the brain where seizures originate is abnormal not only in function but also in structure and is clearly visible in an MRI scan. Mild developmental disorders of the brain are not always visible in an MRI scan, but if the area where epileptic seizures originate can be sufficiently accurately determined using other methods, surgery remains a viable option. If surgical removal of the area is not possible, seizures can sometimes be alleviated by surgically cutting the routes by which seizures spread across the brain.
Temporal lobe epilepsy is the best-known type of adult epilepsy, which is poorly managed with anti-epileptic drugs and can often be surgically treated. Seizures typically start with an aura and progress to an absence seizure. An MRI scan may show scarring on the inner surface of the temporal lobe and neural cells replaced by glial cells (mesial temporal sclerosis). In temporal lobe epilepsy, a normal MRI scan of the brain does not necessarily rule out the possibility of surgical intervention. During the operation, the tip of the temporal lobe and damaged internal sections are removed. Prior to surgery, it is determined whether the damage affects one or both of the temporal lobes and if the remaining temporal lobe functions sufficiently well. Studies show that 70 to 80% of patients who have surgery for temporal lobe epilepsy become completely free of seizures.
Patients continue taking anti-epileptic drugs even after surgery, but the doses can be decreased if there are no seizures. In some children, anti-epileptic drugs can be withdrawn after surgery.
Examinations before surgery
- Video EEG Monitoring
- An MRI scan of the brain
- Examinations by a neuropsychologist, speech therapist, physiotherapist and an occupational therapist
- SPECT (Single Photon Emission Computed Tomography) – imaging which measures blood flow in epileptic discharge areas
- PET (Positron Emission Tomography) – an imaging technique to measure cerebral metabolism
- MEG (Magnetoencephalography) – a technique to measure magnetic fields occurring in the abnormal electrical discharge areas
- Functional MRI
- Wada Test – shows where speech and memory are located in the brain
- Transcranial magnetic stimulation – locating the functions of the cerebral cortex with the help of magnetic field induced stimuli
- Visual field examination
- Intracranial EEG monitoring
The examinations and analysing the results often take a few months. Specialists from different fields participate in the planning of the surgery. For patients with severe epilepsy, surgery offers an opportunity to become completely free of seizures or at least experience significantly fewer intensive seizures. However, the assessment of possible surgical options, waiting for surgery and undergoing surgery are often very trying for the patient as well as their family and close friends. Therefore, all patients will meet with a psychiatrist or child psychiatrist, if possible, when surgery is first considered.
In patients where the examinations confirm that surgery is not an appropriate option, the pre-operative examinations, nevertheless, give additional information on the patients’ seizure type, enabling more effective anti-epileptic therapy. In some cases, vagus nerve stimulation (VNS) or diet therapy may be recommended.
At HUCH, several specialties participate in epilepsy surgery:
- HUCH Department of Neurosurgery
- HUCH Department of Pediatric Neurology/Epilepsy Unit
- HUCH Department of Neurology
- HUS Medical Imaging Center
- HUSLAB: Department of Radioisotope Imaging and the Department of Clinical Neurophysiology
- Biomag Laboratory (MEG, TMS)