Empty or Partial Empty Sella: Effect Not Cause
An empty or partially empty sella does not cause IIH or NPH—rather, it is a radiographic consequence of chronically elevated intracranial pressure in IIH. The relationship is reversed from what the question implies.
The Actual Relationship
Empty Sella as a Result of IIH
The empty or partially empty sella is one of the typical neuroimaging features found in raised intracranial pressure, not a causative factor 1. The 2018 consensus guidelines explicitly list "empty sella" and "partially empty sella/decreased pituitary height" as imaging findings that result from elevated ICP 1.
The mechanism is straightforward:
- Chronically elevated intracranial pressure causes herniation of CSF-filled subarachnoid space through an incomplete or patulous diaphragma sellae into the sella turcica 2
- This creates the radiographic appearance of an "empty" sella
- The finding can actually reverse with successful IIH treatment, as demonstrated in patients whose empty sella normalized after acetazolamide therapy or lumboperitoneal shunting 2
Diagnostic Utility
The empty sella serves as a highly specific imaging marker for IIH (specificity 95.3%) when evaluating patients with suspected elevated ICP 3. However, its absence does not exclude IIH—the finding helps confirm the diagnosis but is not required 3.
Distinguishing Clinical Significance
When Empty Sella Indicates IIH
An empty sella should raise concern for chronically elevated ICP when accompanied by 4:
- Younger age (mean 36 years vs 54 years for incidental findings)
- Headache (93% vs 33% in incidental cases)
- Visual complaints (66% vs 28%)
- Increased scalp thickness (9.0 vs 6.4 mm)
- Other orbital findings: posterior globe flattening, optic nerve sheath distension, optic nerve tortuosity 1, 5
Incidental Empty Sella
Empty sella of normal size is a frequent and probably normal finding in unselected autopsy series 6. Many patients have incidental empty sella without elevated ICP, particularly older patients without associated symptoms 4.
No Relationship to NPH
There is no established causal relationship between empty/partially empty sella and normal-pressure hydrocephalus. These are distinct entities with different pathophysiology. NPH involves ventricular enlargement with normal opening pressure, while IIH involves elevated pressure with typically normal or slit-like ventricles 1.
Clinical Pitfall to Avoid
Do not mistake the empty sella as the primary pathology requiring treatment. The underlying elevated ICP in IIH requires management through weight loss, acetazolamide, or surgical CSF diversion when vision is threatened 1. The empty sella itself needs no specific intervention and may normalize with successful ICP reduction 2.