Empty sella syndrome is a rare disorder characterized by enlargement or malformation of a structure in the head known as the sella turcica. The sella turcica is a saddle-shaped depression located in the bone at the base of skull (sphenoid bone), in which resides the pituitary gland. In empty sella syndrome, the malformed sella turcica is often either partially or completely filled with cerebrospinal fluid. As a result, the pituitary gland is often compressed and flattened so that the sella turcica appears empty. Most individuals with empty sella syndrome do not have any associated symptoms. Occasionally, headaches or pituitary dysfunction may occur. Empty sella syndrome may occur as a primary disorder, for which the cause is unknown (idiopathic), or as a secondary disorder, in which it occurs due to an underlying condition or disorder such as a pituitary tumor or trauma in the pituitary region.