Epilepsy surgery

Epilepsy surgery

The epilepsy surgery Functional Unit (FU) is part of the overall epilepsy care offer at the Necker-Enfants malades university hospital.

FU cares for children with lesional epilepsy at all stages :

  • pre-surgical (surface EEG, intracranial SEEG recordings),
  • surgery,
  • post-operative follow-up,
  • transition to adulthood.

It is the result of the synergy on the Necker site of the pediatric neurosurgery department and the reference center for rare epilepsy (CRéER), but also of the collaboration with the establishments of the Assistance Publique-Hôpitaux de Paris and the university of Paris 5 such as the Robert-Debré hospital or the Sainte-Anne hospital. The Necker site is dedicated to pediatric patients, and the entire environment is adapted to the specific care of sick children.

The scientific environment on site with the Imagine Institute makes it possible to develop innovations and fundamental research for the benefit of our patients.


Médecin responsable

Contact us

Contact information

Necker-Enfants malades university hospital

149 rue de Sèvres
75743 PARIS Cedex 15

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The effectiveness of antiepileptic treatments is frequently incomplete in cases of lesional origin of the seizures.

Epilepsy surgery consists of removing the brain lesion that initiates epileptic seizures, whether developmental (focal cortical dysplasia, hemimegalencephaly), benign tumor (gangliogliomas, DNET), vascular or inflammatory. The type of surgery proposed will be adapted from a focal (lesionnectomy) or lobar (lobectomy) ablation to the complete disconnection of a hemisphere (hemispherotomy).

Other techniques such as neuromodulation by stimulation of the vagus nerve can be proposed in case of resistance to anti-epileptic drugs, in case of contraindication to a resection.

The decision is collegial, after an in-depth assessment by the teams of a reference center.

It must be ensured that the epileptic seizures are initiated in a limited area of the brain and that the removal of this area will not have neurological consequences on functions such as motor skills, language, vision…

After a clinical evaluation by the pediatric neurologist, additional tests are performed: :

  • brain imaging (MRI) with a protocol dedicated to epilepsy,
  • a video EEG,
  • a neuropsychological assessment (phase 1 assessment).

The whole medical team then meets at the monthly epilepsy surgery staff and if the elements are concordant, the surgical intervention is proposed. When there is a discrepancy between the phase 1 examinations, or in case of functional risk, an intracranial recording of the EEG can be proposed (SEEG, phase 2 assessment).

Electroencephalogram (EEG)


The child is hospitalized for a period of 48 hours to 10 days to record the child’s usual seizures. EEG recording electrodes are glued to the scalp skin and connected to a brain electrical activity (EEG) recording system. The chamber is filmed 24 hours a day to analyze the behavioral changes associated with seizures and compare them to the EEG printout. Decreased antiepileptic treatment (drug withdrawal) may be necessary to facilitate seizure occurrence.


Cerebral magnetic resonance imaging allows us to visualize the morphological and functional abnormalities at the origin of epilepsy. This examination must be performed on a powerful machine (3 teslas) with sequences dedicated to an epilepsy protocol. The examination lasts between 20 and 40 minutes, and requires the immobility of the child.

Neuropsychological assessment



When the lesion is poorly limited in MRI or in case of discrepancy between the radiological data and the video EEG, the decision for intracranial brain mapping is taken in a multi-disciplinary meeting.

The operation is performed under general anesthesia in stereotactic conditions. EEG recording electrodes are inserted with infra millimetric precision with the help of a stereotaxis frame or a surgical robot. An MRI is performed immediately after implantation to check the correct positioning of the electrodes and the absence of complications (intracerebral hemorrhage).

After a night in the continuing care unit, the child goes back up to the recording room of the neurosurgery department, and the electrodes are connected to the recording system. The goal is to record the child’s usual seizures to determine their exact starting point. Electrical stimulation of the cortex is also carried out to map the functional areas of the brain (motor skills, language, vision…) and to try to trigger the seizures.

Lesionectomies and lobar resections

When the MRI finds a very limited focal anomaly compatible with the seizures recorded in video EEG, a focal resection is possible.

The main pathologies are developmental malformations of the cerebral cortex (focal cortical dysplasia), benign tumors associated with epilepsy (gangliogliomas, DNET dysembrioplasic tumors), vascular lesions (cavernomas, AVM). In case of temporal localization, it is sometimes necessary to perform an excision when it is pathological. Ablation of the tonsil nucleus and the hippocampus can cause transient mood and memory abnormalities that will be detected during the neuropsychological assessment and re-educated.

The surgical principle is to perform the removal of the lesion and the peri lesional cortex (gyrectomy). These interventions are performed with preoperative imaging guidance (neuronavigation), under an operating microscope, and according to the principles of microsurgery to respect the healthy brain.

The duration of hospitalization is 5 days, including 24-48 hours in continuous monitoring unit-resuscitation unit.

Patients are reviewed at 3 months postoperatively to perform an MRI and an EEG control, then at one year postoperatively to control the MRI, the EEG and perform a neuropsychological assessment during a day hospitalization.

Surgical success is obtained in more than 80% of the cases operated on, allowing the progressive reduction and then the discontinuation of antiepileptic treatments.

Hemispheric surgery

Certain pathologies cause epilepsy in one of the two cerebral hemispheres as a whole. These may be congenital (cortical developmental deformities, hemimegalencephalies, Sturge Weber syndrome), acquired (perinatal stroke) or inflammatory (Rasmussen’s encephalitis) abnormalities.

In most cases, preoperative neurological deficits already exist: hemiparesis, visual disorders, language acquisition delay, cognitive delay.

Epilepsy is primarily drug-resistant and the seizures evolve according to the child’s age: spasms, tonicoclonic seizures, contact breaks, continuous partial epilepsy.

The principle of the surgery is to disconnect the entire diseased hemisphere so that epileptic abnormalities can no longer be propagated. It is a major surgery, the consequences of which are always an aggravation of the preoperative neurological signs: motor deficit, visual field impairment, memory and language depending on the side operated on.

The children are hospitalized for about 15 days in neurosurgery, including 4 to 5 days in intensive care, then for several weeks in neurological rehabilitation.

The main complication is the occurrence in 10 to 20% of cases of hydrocephalus which will require drainage.

Surgical success is obtained in 80% of the cases operated on, with a disappearance of epileptic seizures. Rehabilitation allows the patient to recover or learn to walk, to speak and, eventually, to become autonomous.

Hypothalamic hamartomas

The localization of hyperexcitable ectopic neurons in the hypothalamus can lead to a characteristic clinical picture: gelastic seizures.

Vagus nerve stimulation

The antiepileptic effect is obtained by modulating brain activity through chronic intermittent electrical stimulation of the vagus nerve.

The intervention requires 2 nights of hospitalization and is not very painful. The main risk is infection, which requires the removal of the material and antibiotic therapy.

Approximately 50% of patients are defined as responders, with a reduction of at least 50% in the frequency of attacks, at least one year after the VNS procedure. Most patients and their families also report improved quality of life and wakefulness.

The procedure requires 2 nights of hospitalization. The electrode is placed in the neck on the vagus nerve and connected to the generator positioned behind the pectoral muscle. The 2 scars are closed by absorbable threads and biological glue, it is necessary to check them twice in a dressing consultation with the referring nurse the week following the surgery and to wear a custom-made compression jacket for 3 to 4 weeks. The intensity of stimulation is gradually increased during regular consultations with the pediatric neurologist until the effective current dose is reached.