Empty Sella Turcica: Causes and Clinical Significance
Empty sella turcica occurs when cerebrospinal fluid fills the sella turcica through a defect in the sellar diaphragm, compressing the pituitary gland against the sellar floor and walls. This can arise from multiple mechanisms, both primary (idiopathic) and secondary (acquired) causes 1.
Primary Mechanisms
Anatomical Defect with CSF Herniation
The most common mechanism involves herniation of the subarachnoid space through an incompetent or deficient sellar diaphragm, allowing CSF to enter and fill the sella 2, 3. This can occur with or without elevated intracranial pressure.
Increased Intracranial Pressure
Chronically elevated intracranial pressure is a significant contributor, particularly in younger, obese patients. The classic demographic is obese, hypertensive, multiparous women 2, 4. Idiopathic intracranial hypertension (IIH) is strongly associated with empty sella—93% of IIH patients show orbital findings suggestive of elevated pressure compared to only 14% with incidental empty sella 4.
Spontaneous Pituitary Adenoma Necrosis
An important but underrecognized cause is spontaneous necrosis of a previous pituitary adenoma 5. This theory explains why many patients with empty sella have pituitary insufficiency, hypersecretion, or visual field defects—these represent residual manifestations of the original adenoma 5. The empty sella essentially represents a late stage in the natural history of some pituitary tumors.
Secondary Causes
Secondary empty sella results from identifiable pituitary injury:
- Pituitary apoplexy (hemorrhage or infarction)
- Surgical resection of pituitary tumors
- Radiation therapy to the sellar region
- Traumatic brain injury (significant predictor with P = 0.003) 1
- Previous pituitary gland hypertrophy (e.g., pregnancy-related) with subsequent involution 5
Clinical Implications and Risk Stratification
Hormonal Dysfunction Risk
The presence of empty sella carries substantial risk for hypopituitarism, particularly when discovered due to clinical suspicion rather than incidentally. In primary empty sella, 40.5% of patients exhibit one or more pituitary axis deficiencies, though this drops to 29% in incidentally discovered cases 1.
Key predictors of hypopituitarism include:
- Male sex (P = 0.02)
- Clinical suspicion versus incidental finding (P <0.001)
- Traumatic brain injury history (P = 0.003)
- Total empty sella versus partial (higher risk)
- Progression from partial to total empty sella (associated with hormonal deterioration, P = 0.006) 1
Specific Hormone Deficiencies
In clinically suspicious cases versus incidental findings:
- Hypogonadism: 50.4% vs 8.5%
- Hypothyroidism: 29.2% vs 2.8%
- Growth hormone deficiency: 20.4% vs 12.5%
- Hyperprolactinemia: 15.7% vs 2.9%
- Hypocortisolism: 17.7% vs 13.5% (similar rates)
- Diabetes insipidus: 1.7% vs 0.9% (similar rates) 1
Distinguishing Incidental from Pathologic Empty Sella
Patients with IIH-related empty sella are significantly younger (mean age 36.1 vs 54.3 years), more likely to report headaches (93.3% vs 32.6%) and visual complaints (66.2% vs 28.3%), and show greater scalp thickness (9.0 vs 6.4 mm) and neck soft-tissue thickness (19.5 vs 13.8 mm) 4.
Pediatric Considerations
In children, empty sella is more clinically significant than in adults and more frequently associated with endocrinopathies 2. The incidence ranges from 1.2% in children without endocrine symptoms to 68% in those with known endocrinopathy. Growth hormone deficiency, hypogonadotropism, and multiple pituitary hormone deficiencies are particularly common 2.
Associated Conditions
Empty sella shows strong clinical associations with:
- Spontaneous CSF leaks and nasal meningoencephaloceles: 15 of 16 patients with spontaneous encephaloceles had empty or partially empty sellas, with mean CSF pressure of 28.3 cm H₂O (normal <15 cm) 6
- Benign intracranial hypertension
- Obesity (mean BMI 35.9 kg/m² in affected patients) 6
Common Pitfalls
Do not assume empty sella is always benign or incidental. While often asymptomatic, the condition warrants endocrine evaluation given the 29-40% risk of hormonal dysfunction even in incidental cases 1, 7. The discrepancy between high reported prevalence of pituitary insufficiency (52% in pooled analysis) and low prevalence in epidemiologic studies suggests many cases go unrecognized 7.
Pituitary volume does not correlate with function—even partial empty sella can cause significant hormonal deficits 1.