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DOI: 10.1055/s-0033-1336169
Relationship of Optic Chiasm to Sella Turcica and Pituitary Stalk: Correlation of Cadaveric and Imaging Findings
Introduction: The relationship between the optic apparatus and the skull base is important during approaches near the sella turcica. One relationship that dictates what approach is taken is whether the optic chiasm is pre- or postfixed or in a “normal” location, that is, centered over the diaphragma sella. To our knowledge, the relationship between the position of the chiasm and the angulation of the pituitary stalk has not been investigated.
Materials and Methods: Forty adult cadavers without intracranial pathology were dissected and then parasagittally hemisected just lateral to the sella turcica. In each specimen, the angulation between the pre- and postfixed and normal chiasm and the pituitary stalk was evaluated under surgical magnification. Additionally, 50 MRIs, performed to evaluate for headache, were observed for these relationships.
Results: For cadavers, we found that the chiasm was prefixed in 7.5% (n = 3), normal in 85% (n = 34), and postfixed in 7.5% (n = 3). On imaging, the chiasm was prefixed in 4% (n = 2), normal in 88% (n = 44), and postfixed in 8% (n = 4). For all groups, the relation between the type of chiasm and the pituitary stalk was more often (P < 0.05) a 90-degreeor acute angle for prefixed chiasmata and an obtuse angle for a normal or postfixed chiasmata.
Conclusions: Such data as found in the present study may assist the skull base surgeon during the planning and approaching pathology near the optic chiasm and pituitary stalk.