Is the anatomical lesion always guilty?: A case report

Area of Science:

• Neurology
• Neurosurgery
• Epileptology

Background:

• Presurgical evaluation for epilepsy often requires invasive electroencephalography (EEG) when structural and electroclinical findings are discordant.
• Accurate localization of the epileptogenic zone is critical for successful epilepsy surgery.

Observation:

• A 44-year-old woman with a history of focal seizures presented with conflicting MRI findings (left precentral lesion) and EEG data (right fronto-central ictal onset).
• Video-EEG monitoring revealed interictal sharp waves in bilateral fronto-central regions and post-ictal left arm weakness.
• Ictal EEG showed bilateral fronto-central rhythmic slow activity, predominantly over the right hemisphere.

Findings:

• Stereo-EEG implantation confirmed the seizure onset in the right fronto-central region, contradicting the initial structural imaging.
• Stereo-EEG-guided radiofrequency thermocoagulation resulted in 9 months of seizure freedom.
• Subsequent surgery (right fronto-central cortectomy) revealed focal cortical dysplasia type Ia, with an Engel Ia outcome.

Implications:

• Structural lesions alone are insufficient to pinpoint the epileptogenic zone in epilepsy surgery candidates.
• Invasive EEG investigations like stereo-EEG are essential for resolving discordant localization and guiding treatment.
• Accurate identification of the epileptogenic zone through invasive methods significantly improves surgical outcomes and seizure control.