A partially empty sella develops when cerebrospinal fluid pushes into the bony pocket at the base of the skull that houses the pituitary gland, compressing the gland but not eliminating it entirely. The most common underlying reason is a combination of two factors: a weak or incomplete membrane covering that pocket, and pressure from the fluid that bathes the brain. In many people, this happens silently and shows up only as a surprise finding on a brain scan done for an unrelated reason. But in a meaningful minority, it signals an identifiable medical problem, from chronically elevated pressure inside the skull to the aftermath of pituitary surgery or severe postpartum bleeding.
How the Sella Normally Works and What Goes Wrong
The sella turcica is a saddle-shaped depression in the sphenoid bone, right behind your nose. The pituitary gland sits inside it, protected from above by a sheet of tough tissue called the diaphragma sellae. Think of this membrane as a lid over a cup. In a healthy setup, the lid is snug enough that the cerebrospinal fluid circulating above cannot trickle down and press on the gland below.
When that membrane is incomplete or abnormally thin, cerebrospinal fluid can herniate through the gap and gradually compress the pituitary against the floor of the sella. On an MRI, the gland looks flattened and the space above it appears filled with fluid. If the gland is thinned but still visible, the finding is called a partially empty sella. If the gland is barely detectable, it is classified as a complete empty sella. A 2024 review in Endocrine Practice defines a complete empty sella as a gland thickness of 2 mm or less with more than half the sella occupied by cerebrospinal fluid; a partial form involves less extreme compression.1Endocrine Practice. A Comprehensive Review of Empty Sella and Empty Sella Syndrome
Primary Causes: When No Other Disease Is Found
The most frequently discussed scenario is primary empty sella, where the finding exists without a tumor, surgery, infection, or other identifiable trigger. Estimates of how common this is vary widely. One German review placed the range at roughly 2% to 20% of the general population, while other estimates extend as high as 35%.2PubMed Central. Primary Empty Sella Syndrome and the Prevalence of Hormonal Dysregulation 3PubMed Central. Asymptomatic Empty Sella: A Literature Review and Suggestions for Evaluation in Clinical Practice That broad range reflects the fact that most cases are caught incidentally on scans done for headaches or other complaints, so true population rates depend heavily on who gets scanned. The condition is considerably more common in women, with some data suggesting a ratio of about five women to every one man.4PubMed Central. Partial empty sella syndrome: a case report and review
In the primary form, the leading explanation centers on two ingredients acting together. First, the diaphragma sellae has to be deficient, either because it never fully developed or because it has weakened over time. Second, there needs to be enough downward force from cerebrospinal fluid to push through that opening. The traditional theory held that chronically elevated intracranial pressure was responsible, but a study that directly monitored pressure in patients with empty sellas found a more nuanced picture: only two of five patients had clearly elevated pressure, while in three others the pressure was normal.5PubMed Central. Intracranial pressure in patients with the empty sella syndrome without benign intracranial hypertension The researchers proposed that even normal pulsations of cerebrospinal fluid, the rhythmic waves generated by each heartbeat, could be enough to gradually reshape the gland when the membrane above it is deficient. In other words, the weak lid matters just as much as the pressure behind the fluid.
The Connection to Idiopathic Intracranial Hypertension
While normal pressure can sometimes produce a partially empty sella, genuinely elevated intracranial pressure accelerates the process dramatically. The clearest example is idiopathic intracranial hypertension, a condition in which pressure inside the skull rises for no obvious structural reason. It affects predominantly overweight women of childbearing age and causes headaches, vision changes, and pulsatile tinnitus. An empty or partially empty sella is so characteristic of this condition that it is listed among the hallmark imaging findings, alongside swollen optic nerve sheaths and narrowed venous sinuses.6PubMed Central. Idiopathic intracranial hypertension: ongoing clinical challenges and future prospects
The mechanism is straightforward. Higher-than-normal cerebrospinal fluid pressure pushes more forcefully through any gap in the diaphragma sellae, compressing the pituitary from above. One review noted that an empty sella is “particularly common” in the setting of idiopathic intracranial hypertension.7PubMed. Factors determining the clinical significance of an “empty” sella turcica In a pair of reported cases, the empty sella actually reversed after the intracranial hypertension was treated, with the pituitary gland reexpanding on follow-up imaging.8PubMed Central. Reversible empty sella in idiopathic intracranial hypertension: an indicator of successful therapy? That reversal is a useful clue: it confirms the gland is being squished, not destroyed, at least in the early stages.
For clinicians, this link means that discovering a partially empty sella should prompt a question: does this patient have signs of elevated intracranial pressure? Headaches that worsen when lying down, transient visual obscurations, and papilledema on an eye exam all point toward idiopathic intracranial hypertension rather than a benign incidental finding.
Secondary Causes: Surgery, Bleeding, and Inflammation
When the partially empty sella results from a known prior event, it is classified as secondary. Several distinct mechanisms can produce it.
Pituitary Surgery
Removing a pituitary tumor, whether through the nose or through the skull, leaves a cavity behind. Once the tumor tissue is gone, the diaphragma sellae is left unsupported and cerebrospinal fluid fills the void. This is one of the most straightforward causes of a secondary empty sella.9PubMed Central. Resolution of symptomatic secondary empty sella syndrome following lumbar-peritoneal shunt The larger the tumor that was removed, the more space there is for fluid to occupy. In rare cases, the stalk connecting the pituitary to the brain can become disrupted as a consequence, further compromising hormonal signaling.10PubMed Central. Radiographic pituitary stalk disruption: A rare sequela of secondary empty sella syndrome
Postpartum Pituitary Damage
Sheehan’s syndrome occurs when severe blood loss during or after childbirth cuts off the blood supply to the pituitary gland, causing tissue death. A study of 13 women with postpartum hypopituitarism found that 11 had an empty or partially empty sella on CT scanning. In six of the seven women with classic Sheehan’s syndrome, demonstrable pituitary tissue was essentially absent, and the sella was filled with fluid. Strikingly, the sella itself was normal-sized in most of these patients, not enlarged, which distinguishes the appearance from a tumor-related empty sella.11The American Journal of Medicine. Empty sella of normal size in Sheehan’s syndrome
Autoimmune Inflammation of the Pituitary
Lymphocytic hypophysitis is an autoimmune condition in which the immune system attacks the pituitary gland. In its early phase, the gland swells. Over months to years, the inflammation burns itself out and the gland shrinks, sometimes to the point of an empty sella. A mouse model of this disease tracked the progression on MRI: all immunized mice showed early pituitary enlargement, followed by gradual volume loss, with about 78% reaching empty sella values by roughly 300 days after the immune attack began.12PubMed Central. From pituitary expansion to empty sella: disease progression in a mouse model of autoimmune hypophysitis A clinical case report corroborated this timeline in a human patient, documenting the natural course of lymphocytic hypophysitis over 13 years, with the empty sella as the final outcome.13PubMed. Empty sella may be the final outcome in lymphocytic hypophysitis
Other Rare Triggers
Radiation therapy to the pituitary region, pituitary apoplexy (a sudden bleed into the gland), and certain cystic lesions can also lead to a partially empty sella. One early case report described an empty sella caused by a large Rathke’s cleft cyst, a benign developmental remnant that expanded and destroyed surrounding tissue.14Acta Neurochirurgica. The Empty Sella syndrome secondary to Rathke’s cleft cyst These situations are uncommon but worth keeping on the differential when a partially empty sella turns up alongside unexpected symptoms.
Why the “Partial” Distinction Matters
The difference between a partially and completely empty sella is not just academic. A partially empty sella suggests the pituitary gland is compressed but still has measurable tissue. That residual tissue usually retains at least some hormone-producing ability. In primary cases discovered incidentally, many people have entirely normal pituitary function. Complete empty sella, by contrast, leaves less working tissue and is more likely to be associated with hormonal deficiencies.
That said, “partially empty” does not guarantee everything is fine. The degree of hormonal disruption depends on which cells in the gland have been compressed and how severely. Growth hormone and gonadotropin (the hormones driving puberty and fertility) tend to be the most vulnerable, while cortisol production is often preserved until very late. This is why even an incidentally discovered partially empty sella should be followed up with bloodwork to check pituitary hormone levels, even if the person feels perfectly well.
Visual Symptoms and the Optic Chiasm
The optic chiasm, where the two optic nerves partially cross, sits right above the pituitary gland. When the sella empties, the chiasm can sag downward into the void, a phenomenon sometimes called chiasmal herniation. This traction on the nerve fibers can produce visual field deficits and, in severe cases, progressive vision loss. A systematic review noted that the anatomical distortion caused by displacement of the optic chiasm and traction on the pituitary stalk can cause direct injury to nerve fibers and ischemic damage to the blood supply of the visual system.15PubMed. Treatment of empty sella associated with visual impairment: a systematic review of chiasmapexy techniques
Visual problems are far from universal. Most people with a partially empty sella never notice any change in their eyesight. The risk goes up with more complete forms of the condition and with sellas that are significantly enlarged, giving the chiasm more room to drop. When visual symptoms do develop, surgical techniques exist to pack material into the empty sella and lift the chiasm back into a normal position.
Cerebrospinal Fluid Leaks
An empty or partially empty sella can occasionally create a pathway for cerebrospinal fluid to escape downward through the skull base and into the nose. The result is spontaneous cerebrospinal fluid rhinorrhea, a clear, watery nasal drip that is easy to mistake for allergies. In one study of patients with spontaneous nasal cerebrospinal fluid leaks, every single patient who had sella imaging showed either a completely or partially empty sella.16PubMed. Significance of empty sella in cerebrospinal fluid leaks A large case series of 142 patients with primary empty sella found that those who developed rhinorrhea required various treatments, including shunt placement, surgical repair of the sellar floor, or both.17Journal of Neurosurgery. Primary empty sella syndrome in a series of 142 patients
This complication matters because cerebrospinal fluid leaks carry a risk of meningitis. A clear runny nose that gets worse when leaning forward, tastes salty, and occurs mostly from one side warrants medical evaluation rather than a trip to the pharmacy for antihistamines.
Empty Sella in Children
Most discussions of empty sella focus on adults, especially middle-aged women. But it does occur in children, where the stakes can be different. Growth hormone deficiency is a particular concern in pediatric cases because it directly affects height and development. A Turkish study of children with primary empty sella found that the most common presentations were short stature, pubertal delay, and neurological symptoms like headaches and dizziness. Five of the short children in the cohort had confirmed growth hormone deficiency.18The Turkish Journal of Pediatrics. Clinical course of primary empty sella in children: a single-center experience A separate case report described an infant with failure to thrive and hypopituitarism traced to empty sella syndrome.19PubMed Central. Empty sella syndrome in a male child with failure to thrive
In children, then, a partially empty sella is less likely to be a harmless incidental finding and more likely to be functionally significant. Pediatric endocrinologists typically screen for growth hormone, thyroid, and adrenal deficiencies when the imaging finding turns up in a young patient.
Can a Partially Empty Sella Reverse?
In most cases, the structural change is permanent but stable. The gland does not continue to shrink indefinitely, and many people live decades with a partially empty sella and no progression. However, there are documented instances of reversal. As mentioned earlier, patients with idiopathic intracranial hypertension have shown reexpansion of the pituitary gland after their pressure was lowered. One case report described a patient whose empty sella appearance resolved after a lumbar puncture that drained excess cerebrospinal fluid, suggesting the gland was being dynamically compressed rather than permanently destroyed.20PubMed. An Unusual Case of Reversible Empty Sella
These reversals remain uncommon and tend to occur when the underlying cause is actively managed. Nobody should expect a partially empty sella to spontaneously refill on its own. But the possibility of reversal reinforces an important point: in many cases, the gland is being compressed, not obliterated, and removing the source of compression can restore its architecture.
When an Incidental Finding Needs Workup
With brain MRIs now routine for an enormous range of complaints, incidental discovery of a partially empty sella has become common. The key question is always whether this is a quiet anatomical variant or a clue to something requiring treatment. Factors that push toward further investigation include headaches with features suggestive of elevated intracranial pressure, unexplained visual changes, any sign of hormonal dysfunction (fatigue, irregular periods, reduced libido, unexplained weight changes), and a history of conditions associated with secondary empty sella such as prior pituitary surgery, postpartum hemorrhage, or autoimmune disease.
For a person with a completely incidental finding on an MRI ordered for, say, migraines, and no symptoms pointing toward hormonal or visual problems, the evaluation is usually straightforward: baseline pituitary bloodwork, an eye exam if warranted, and periodic monitoring. A partially empty sella alone, absent red flags, generally does not require treatment. It becomes clinically meaningful only when it is accompanied by symptoms or hormonal deficits that match the anatomical finding.
Obesity, Female Sex, and the Risk Factor Profile
Obesity appears repeatedly in the literature as a risk factor for primary empty sella, likely because excess weight is itself a driver of elevated intracranial pressure. The connection runs partly through idiopathic intracranial hypertension, which is strongly associated with high body mass index. But even outside a formal diagnosis of intracranial hypertension, higher weight correlates with higher baseline cerebrospinal fluid pressure, which in turn increases the mechanical force acting on a weak diaphragma sellae.
The female predominance, consistently around five to one in the primary form, is not fully explained. Hormonal factors may play a role. Pregnancy causes the pituitary to enlarge, and the gland’s subsequent return to normal size after delivery could leave the diaphragma sellae stretched. Multiple pregnancies amplify this effect. Other proposed contributors include the higher prevalence of idiopathic intracranial hypertension and obesity in women, creating overlapping risk factors that compound one another. Despite decades of observation, the exact reasons for the sex difference remain an active research question rather than a settled answer.