Assessment of MRI-guided HIFU for Patients With Drug-resistant Focal Epilepsy

Epilepsy is a common, long-lasting neurological disorder with significant social ramifications. In France, it is estimated that over 500,000 individuals are affected by epilepsy, with 50,000 experiencing drug-resistant partial epilepsy. Approximately 10,000 patients with drug-resistant partial epilepsy may benefit from neurosurgical treatment to excise their epileptogenic focus. However, only 300 operations are performed annually in France. Epilepsy surgery not only has medical benefits (with 50-80% of operated patients being seizure-free), but also reduces the risk of excess mortality in this population. Furthermore, it is a cost-effective solution, as drug-resistant epileptic patients can cost up to $138,000 in treatment and monitoring throughout their lifetime. High-Intensity Focused Ultrasound (HIFU) is a noninvasive method that uses heat to destroy brain lesions, leading to coagulation and necrosis of the lesion under control. It has been successfully used to treat essential tremors, Parkinson's disease, and neuropathic pain, and may be used to treat epilepsy lesions that are inaccessible to conventional surgery, located in eloquent areas, or in patients with contraindications to general anesthesia. The goal of this study is to assess the feasibility, tolerance, and safety of HIFU use in lesions responsible for drug-resistant epilepsy, as this represents the first use of HIFU for this indication.

Main objective : To assess the feasibility of employing HIFU-based thermoablation for the treatment of drug-resistant epilepsy caused by intracerebral lesions.

Inclusion criteria

• Age ≥18 years old
• Patient with drug-resistant epilepsy according to ILAE definition
• Patient presenting lesional image(s) on morphological MRI responsible for epilepsy according to clinical and electrophysiological evaluation, +/-PET+/- SPECT+/-sEEG
• Patients for whom neurosurgical treatment by craniotomy is not possible: deep-seated lesions, lesions in the eloquent area, patient reluctance to have a surgical procedure with craniotomy, contraindication to general anesthesia
• Patient affiliated to a social security scheme
• The patients signed an informed consent form.

Exclusion criteria

• Drug-sensitive epilepsy
• Patients exhibiting suboptimal adherence to medication
• Individuals under legal protective measures
• Patients presenting contraindications to Magnetic Resonance Imaging (MRI), such as the presence of metal fragments, allergy to gadolinium, etc.
• Patients with serious and uncontrolled psychiatric disorders
• Pregnant women. Women of reproductive capacity were mandated to use oral contraceptives throughout the study duration.
• Contraindications related to ExAblate treatment:

• patients with implants in the brain or skull.
• patients where it is not possible to avoid energy-absorbing structures or sensitive tissues (e.g., skull density ratio <0.35, areas of anterior brain shunts, surgical clamps, or other hard implants) on the path of the ultrasound beam.
• patients diagnosed with another brain disease (e.g., malignant brain tumors or intracranial aneurysms).
• patients with a history of cerebral hemorrhage, and stroke within the last year.
• patients taking medications that are predisposed to bleeding and have not stopped for two weeks before the procedure.
• patients with severe hypertension that cannot be controlled with medication (diastolic blood pressure >100 mmHg).
• patients who could not communicate with the physician during the treatment.
• patients with unstable cardiac conditions.
• patients with history of abnormal bleeding, intracranial hemorrhage, coagulopathy, or documented risk factors for intraoperative or postoperative bleeding or coagulopathy.
• patients with cerebrovascular disease (multiple strokes or strokes within six months).
• patients with risk factors for intraoperative or postoperative bleeding.
• patients with significant healing in an area located on the path of the intended passage of energy to the treatment area.