Discrepancy between preoperative noninvasive evaluation and intraoperative electrical cortical stimulation for motor...

Area of Science:

• Neuroscience
• Neurosurgery
• Epilepsy Research

Background:

• Hemispherotomy requires evaluating residual motor function and functional compensation.
• Transcranial magnetic stimulation (TMS) is used for hand motor function but cannot assess lower limb function.

Observation:

• A teenage male with a right frontotemporal arachnoid cyst, polymicrogyria, and gyral dysplasia presented with seizures.
• Functional MRI (fMRI) and TMS indicated the left primary motor cortex controlled bilateral motor responses.
• Intraoperative cortical stimulation revealed contralateral control of lower limb primary motor areas.

Findings:

• Noninvasive tests alone may be insufficient for surgical strategy in complex epilepsy cases.
• fMRI and TMS findings conflicted with intraoperative stimulation results regarding motor cortex control.

Implications:

• A combination of pre- and intraoperative examinations is essential for safe and effective epilepsy surgery.
• This case highlights the need for comprehensive pre-surgical evaluation to avoid unexpected neurological complications.
• Total callosotomy was performed instead of hemispherotomy due to complex findings.