What is an Empty Sella?
An empty sella is a radiographic finding where cerebrospinal fluid (CSF) fills the sella turcica (the bony cavity housing the pituitary gland), causing compression and flattening of the pituitary gland against the sellar floor and walls. 1
Anatomical Definition
The condition occurs when CSF herniates into the sella turcica through an incompetent or defective sellar diaphragm, creating the appearance of an "empty" sella on imaging despite the pituitary gland still being present but compressed 2. This can range from:
- Partial empty sella: Moderate concavity with visible pituitary tissue
- Total empty sella: Severe flattening with minimal to no visible pituitary tissue 3
Primary vs. Secondary Empty Sella
Primary empty sella develops when CSF enters through a defect in the sellar diaphragm, with or without increased intracranial pressure, in patients without prior pituitary pathology 1, 2.
Secondary empty sella results from injury to the pituitary itself (such as pituitary apoplexy) or follows surgical/radiation treatment 2.
Clinical Significance
Empty sella is predominantly an incidental radiographic finding discovered during imaging for unrelated conditions 4, 5. The estimated prevalence ranges from 2-20% in the general population, with neuroimaging studies showing approximately 12% incidence 5, 6.
When Does It Become Clinically Relevant?
The finding becomes "empty sella syndrome" only when accompanied by endocrine, ophthalmological, or neurological symptoms 4. However, most patients with radiographic empty sella remain asymptomatic throughout their lives 4.
Risk of Pituitary Dysfunction
The critical clinical concern is hypopituitarism:
- Incidentally discovered empty sella: 29% have at least one pituitary hormone deficiency 3
- Clinically symptomatic empty sella: 40.5% exhibit one or more axis deficiencies 3
- Total empty sella carries higher risk than partial empty sella for hormonal dysfunction 3
Specific Hormone Deficiencies
In symptomatic patients versus incidental findings 3:
- Hypothyroidism: 29.2% vs. 2.8%
- Hypogonadism: 50.4% vs. 8.5%
- Growth hormone deficiency: 20.4% vs. 12.5%
- Hypocortisolism: 17.7% vs. 13.5% (similar rates)
Risk Factors for Hypopituitarism
Male sex, clinical suspicion of pituitary disease, and traumatic brain injury predict higher rates of hypopituitarism 3. Progression from partial to total empty sella may be associated with hormonal deterioration 3.
Diagnostic Approach
MRI is the gold standard for radiological diagnosis 5. The finding is graded on sagittal T1 images from Category 1 (normal) to Category 5 (no visible pituitary tissue) 7.
Clinical Pitfalls
- Empty sella is often associated with raised intracranial pressure but is also common (17.4% with severe concavity) in neuro-ophthalmology patients without raised ICP 7
- The finding is mentioned in only 15% of radiology reports despite its frequency 7
- There is a discrepancy between high reported rates of pituitary insufficiency in selected populations versus lower rates in epidemiologic studies, likely due to publication selection bias 6