White Matter Governed Superior Frontal Sulcus Surgical Paradigm: A Radioanatomic Microsurgical Study-Part II

Area of Science:

• Neurosurgery
• Anatomy
• Medical Imaging

Background:

• Kocher's point (KP) has been the standard surgical entry to the frontal horn (FH) for over a century.
• Advances in understanding white matter tracts (WMTs) necessitate re-evaluation of traditional surgical trajectories.
• Optimal FH access requires consideration of adjacent critical neuroanatomical structures.

Purpose of the Study:

• To review existing entry points (EPs) for accessing the frontal horn (FH).
• To introduce the superior frontal sulcus parafascicular entry point (SFSP-EP), also known as the Kassam-Monroy entry point (KM-EP), based on WMT anatomy.
• To compare the KM-EP with KP and its variations regarding WMT traversal.

Main Methods:

• Literature review of studies on FH entry points from 1892-2018, stratified by corridor and intent.
• Anatomical comparison of KM-EP, KP, and variants using cadaveric dissections.
• 3D modeling of WMTs using magnetic resonance-diffusion tensor imaging.

Main Results:

• Analysis of 31 studies revealed that all traditional EPs, including KP and its variations, traverse critical subcortical WMTs.
• The novel KM-EP (x=2.3, y=3.5) was specifically designed to avoid these critical WMTs.
• Traditional KP (x=3, y=1) and its variations place the frontal aslant tract, superior longitudinal fasciculus II, and inferior fronto-occipital fasciculus at risk.

Conclusions:

• Established entry points like Kocher's point pose an anatomical risk to critical white matter tracts.
• The Kassam-Monroy entry point offers a purpose-built, WMT-informed alternative for safer access to the frontal horn.
• Prospective studies are needed to confirm the clinical safety and efficacy of the KM-EP.