= extension of subarachnoid space into sella turcica, which becomes exposed to CSF pulsations ← defect in diaphragma sellae; characterized by normal / molded pituitary gland + normal or enlarged sella (empty sella = misnomer)
Incidence: 24% in autopsy study
- slowly progressive symmetrical / asymmetrical (double floor) enlargement of sella
- remodeled lamina dura remains mineralized
- small rim of pituitary tissue displaced posteriorly + inferiorly
- “infundibulum” sign = infundibulum extends to floor of sella
DDx: cystic tumor, large herniated 3rd ventricle (displaced infundibulum)
Incidence: 10% of adult population; M÷F = 1÷4
Probable causes:
- pituitary enlargement followed by regression during pregnancy
- involution of a pituitary tumor
- congenital weakness of diaphragma sellae
- Occurs more frequently in patients with increased intracranial pressure
- usually asymptomatic
- increased risk for CSF rhinorrhea
- NO endocrine abnormalities
= postsurgical after disruption of diaphragma sellae
- visual disturbance, headaches