Optic Tract as an Upper Limit in Amygdalectomy: Microsurgical Study

Area of Science:

• Neurosurgery
• Neuroanatomy

Background:

• The upper boundary for amygdala resection remains debated despite known relationships with various amygdala segments.
• The optic tract (OT), situated below the striatopallidal region, is proposed as a key anatomical landmark, yet its microsurgical anatomy is underexplored.

Purpose of the Study:

• To conduct a microsurgical anatomical dissection of the optic tract (OT) along its entire course.
• To detail the superior, inferior, medial, and lateral relationships of the OT.
• To establish the OT's utility as a landmark for superior amygdala resection.

Main Methods:

• Microsurgical anatomical dissection of the optic tract (OT) from the chiasm to the lateral geniculate nucleus.
• Dissection performed on 8 alcohol-fixed human hemispheres.
• Photographic documentation from multiple angles for surgical guidance.

Main Results:

• Detailed anatomical relationships of the OT with surrounding structures including the caudate and hippocampal formations.
• Identification of superior structures (striatopallidal region, superior caudate fasciculus), inferior structures (hippocampus, amygdala, choroidal artery branches, terminal stria, basal vein), medial structures (internal capsule, midbrain), and lateral structures (temporal stem, anterior perforated substance).

Conclusions:

• There is limited literature on the optic tract's anatomy from a neurosurgical viewpoint.
• This microsurgical study elucidates the anatomical path of the optic tract.
• The optic tract is confirmed as a reliable landmark for defining the upper limit in superior amygdala resections.