Empty Sella Syndrome
Empty sella syndrome is a radiological finding where spinal fluid is found within the sella, the space created for the pituitary. Empty sella syndrome is divided into two categories based on degree:
- Partial empty sella syndrome – when less than 50% of the sella is filled with spinal fluid and the pituitary gland thickness ranges from 3 to 7 mm, with 7 mm being the lower limit of normal thickness.
- Total empty sella syndrome – when more than 50% of the sella is filled with spinal fluid and the pituitary gland thickness is less than or equal to 2 mm.
Emtpy sella syndrome can also be categorized based on its cause:
- Primary empty sella syndrome – happens when there is a combination of (i) increased spinal fluid pressure and (ii) a defect in the diaphragma sellae, a membrane that sits on top of the pituitary. Primary empty sella is seen during pregnancy, obesity, and pseudotumor cerebri (a condition of increased spinal fluid pressure seen in obesity and associated with vision loss).
- Secondary empty sella syndrome – happens when the pituitary gland regresses after surgery to remove a pituitary tumor; radiation to treat a pituitary tumor; or a condition that damages the pituitary gland such as an old history of pituitary apoplexy that the patient was unaware of, hypophysitis, or neurosarcoidosis.
Emtpy sella syndrome patients often have impairment of one or more pituitary axes.
Empty sella is often an incidental imaging finding without associated symptoms. If there are symptoms, patients with empty sella syndrome can have headaches as symptoms of elevated spinal fluid pressure; symptoms of hypopituitarism; or visual symptoms, which can sometimes be due to downward, prolapse of the optic chiasm into the empty sella.
Treatment is often not needed since empty sella is often an incidental finding. If there is associated hypopituitarism, hormone replacement is administered as indicated. Neurosurgery may be needed if there is associated chiasm prolapse in need of neurosurgical correction; if a small mciroadenoma is identified within the empty sella (in which case the finding may reflect an apoplexy event that went undiagnosed and reabsorbed over time, leaving behind them empty sella and microadenoma); or if pseudotumor cerebri is diagnosed and a ventriculoperitoneal shunt is needed.
Dr. Yuval Eisenberg, a physician member of the Pituitary Network Association, prepared the following document for NORD (National Organization for Rare Disorders).