Brainstem Surgery: Functional Surgical Anatomy with the Use of an Advanced Modern Intraoperative Neurophysiological...

Area of Science:

• Neurosurgery
• Neurophysiology
• Surgical Neurology

Background:

• Intraoperative neurophysiology (ION) has evolved alongside advancements in brainstem surgery.
• Brainstem mapping (BSM) initially focused on locating cranial nerve motor nuclei (CNMN) but now encompasses broader applications for identifying safe surgical entry zones.
• Corticobulbar tract (CBT) motor evoked potential (MEP) monitoring assesses the functional integrity of the cranial motor pathway during surgery.

Purpose of the Study:

• To describe the neurophysiological aspects of BSM and CBT-MEP monitoring in brainstem surgery.
• To elucidate the anatomical underpinnings relevant to ION procedures in the brainstem.
• To discuss the clinical utility, limitations, and future perspectives of ION in brainstem surgery.

Main Methods:

• Detailed description of the neurophysiological principles of BSM and CBT-MEP.
• Demonstration of relevant anatomical backgrounds, including the floor of the fourth ventricle and CBT anatomy.
• Review of clinical applications and surgical implications of ION procedures.

Main Results:

• Combined BSM and CBT-MEP monitoring are essential for preserving CNMN and their supranuclear innervation.
• BSM aids in avoiding direct damage to CNMN by identifying safe entry zones.
• ION procedures remain vital for safe brainstem surgery, complementing advanced imaging techniques like MRI.

Conclusions:

• The combined application of BSM and CBT-MEP monitoring is indispensable for functional preservation during brainstem surgery.
• ION procedures, including BSM, play a critical role in enhancing the safety of brainstem interventions, even with advanced imaging.
• ION techniques are expected to further support safer brainstem surgeries, with potential new roles in procedures like stereotactic biopsy for diffuse intrinsic pontine gliomas.