Anatomic relationship of the optic radiations to the atrium of the lateral ventricle: description of a novel entry point to the trigone.
OBJECTIVE
The aim of this study was to delineate the anatomic relationship of the optic radiations to the atrium of the lateral ventricle using the Klingler method of white matter fiber dissection. These findings were applied to define a surgical approach to the trigone that avoids injury to the optic radiations.


METHODS
Sixteen cadaveric hemispheres were prepared by several cycles of freezing and thawing. With the use of wooden spatulas, the specimens were dissected in a stepwise fashion. Each hemisphere was dissected first from a lateromedial direction and then from a mediolateral approach, and careful attention was given to the course and direction of the optic radiation fibers at all points from Meyer's loop to their termination at the cuneus and the lingual gyrus.


RESULTS
In all 16 dissected hemispheres, the following observations were made: 1) the entire lateral wall of the lateral ventricle-from the temporal horn to the trigone to the occipital horn-is covered by the optic radiations; and 2) the medial wall of the lateral ventricle in the area of the trigone is entirely free of the optic radiations.


CONCLUSIONS
The results of this study confirm that the medial parieto-occipital interhemispheric approach to the ventricular trigone will avoid injury to the optic radiations and the calcarine cortex. The authors describe the most direct trajectory to the ventricular trigone using this approach and propose a point of entry that transects the cingulate gyrus at a point 5 mm superior and 5 mm posterior to the falcotentorial junction.
Mahaney
Kelly B
KB
Saint Louis University Center for Cerebrovascular and Skull Base Surgery, St. Louis, Missouri, USA.
Abdulrauf
Saleem I
SI
D000328:Adult; D002102:Cadaver; D005829:Geniculate Bodies / Q000033:anatomy & histology*; D006179:Gyrus Cinguli / Q000033:anatomy & histology; D020786:Hemangioma, Cavernous, Central Nervous System / Q000601:surgery*; D006801:Humans; D020547:Lateral Ventricles / Q000033:anatomy & histology* / Q000473:pathology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008866:Microsurgery / Q000379:methods; D019635:Neurosurgical Procedures / Q000379:methods* / Q000592:standards; D013788:Thalamus / Q000473:pathology; D014793:Visual Cortex / Q000033:anatomy & histology*; D014795:Visual Pathways / Q000033:anatomy & histology*