Empty sella is a
radiological diagnosis based on CT or MR investigation. Either a normal
sized (empty sella) or enlarge sella (empty enlarged sella) presents
partly or totally filled with cerebrospinal fluid. The radiological
diagnosis does not mean a pathological situation in every instance. Many
patients present without specific symptoms and the diagnosis is made by
chance. Empty sella syndrome is the pathological variant of a radio
logically verified empty sella.
Primary empty sella
is an idiopathic form of an empty sella which occurs in the absence of
prior pituitary surgery or radiation therapy or medication with DOPA
sella occurs as a result of surgical resection or irradiation of a
The disphragma sellae
normally forms a circular fold that constitutes a roof for the sella
turcica with only a small central opening for the passage of the pituitary
stalk. Busch in 1951 performed an autopsy study of 788 subjects
without known pituitary disease. In 38.4% he found a complete covering of
pituitary gland by the diaphragm. He observed an empty sella in 5.5%.
Other studies described significant defects in the sellar diaphragm in 22%
to 72% of cases. These defects were frequently accompanied by intrasellar
extension of subarachnoid space and downward displacement of the optic
Busch and others have
measured the volume of the sella and of the sellar contents. These
measurements are widely variable because the definition of the lateral and
superior boundaries of the sella is arbitrary. However, Bjerre(1990)
concludes that a sella with a volume exceeding 1.1-1.2cm3
calculated from X-ray is an enlarged sella.
A 5:1 female male
predominance exists in the incidence of diaphragmatic defects.
Over 80% of the cases
occur in women, the majority between the ages of 40 and 49. 78% to 90% of
these patients were described as obese, multiparous and 31% were
hypertensive (Neelon, 1973).
An empty sella of
normal size without clinical significance was found in some 10% (Brisman,
1978). In children radiological incidence of primary empty sella was
reported as 1-48% with a male-female ratio of 1.4:1.0 (Rappaport,
Primary empty sella
An empty sella (either
normal sized or enlarged) may simply be a normal anatomical variation so
that concurrent symptoms are unrelated to the radiological appearance.
If a deficient
diaphragma sellae is present, increased intracranial pressure, as in
displaces the suprasellar arachnoidal and cerebral structures into the
sellar cavity. This may cause sellar enlargement and partial emptiness,
as well as posteroinferior displacement and compression of the pituitary
gland, and displacement of the optic chiasm and erosion of the sellar
floor and dura. The theory is supported by the following observations.
- An empty sella
syndrome is observed frequently in patients with benign intracranial
hypertension. Weisberg (1975) reported an incidence of 10% in 50
cases with benign intracranial hypertension.
intracranial pressure monitoring in patients with empty sella syndrome
revealed intermittent asymptomatic increases in pressure in some
patients (Kaye, 1982).
tumors of slow growth have been associated with a deficient sellar
diaphragma. The incidence of an abnormal sellar configuration in
patients with intracranial tumors and empty sella syndrome is about 24%.
- Patients with
known empty sella followed for some years exhibit progressive changes of
their radiological sellar appearance.
Another theory relates
the empty enlarged sella to a previous pituitary hyperplasia or
hypertrophy (e.g. during pregnancy or because of primary peripheral
endocrine gland insufficiency). This theory explains the fact that empty
enlarged sella is often combined with primary thyroid dysfunction, obesity
and the female preponderance in most series.
Based on observations
patients with acromegaly and hyperprolactinaemia associated with an empty
sella syndrome, sequellae of pituitary apoplexy (extensive hemorrhage or
necrosis within a pituitary adenoma) is blamed.
Another theory proposes
an autoimmune hypophysitis with resulting secondary protrusion
of the arachnoid membrane
through an incompetent
diaphragma sellae. Antipituitary antibodies were diagnosed in 47% to 75%
of adult patients with primary empty sella syndrome.
postpartum necrosis of the pituitary gland may be the cause in some.
Secondary empty sella
has been noted to
- Sellar or
- Radiation therapy
for an intrasellar expansion
therapy for a pituitary adenoma
Empty sella has been associated with
pseudotumor cerebri, hypopituitarism, visual field defects, and headache.
is the most common symptom. Some 70% of patients complain about
pain. Pulsations of CSF against the dura of the sella could be
2) Visual alterations
may be due to traction on the chiasm or involvement of chiasmal blood
vessels. Incidence is about 20% in primary empty sella syndrome. In
secondary empty sella syndrome the incidence is much higher because of the
underlying sellar pathology. Clinically the patients complain about
clouding of vision, color vision defects, photophobia, and various visual
field defects (bitemporal hemi-, or quadrantanopia, generalized filed
constriction, quadrine constriction, central scotoma, homonymous
hemiachromatopsia mimicking the lesion in patients with a suprasellar
pituitary tumour. On fundoscopy changes to the retina and papilledema can
be observed. The symptoms sometimes resemble a low pressure glaucoma thus
necessitating detailed ophthalmologic examination with particular
attention being paid to intraocular pressure and optic disc appearance.
There is general agreement in the literature that anterior pituitary
dysfunction necessitating hormonal replacement therapy is rare in primary
empty sella syndrome. However, subtle dynamic endocrine testing is able
to reveal some degree of hypothalamic-pituitary dysfunction in up to 80%
of the patients assessed. Gallardo in their series of 76 patients
with empty sella syndrome (1992) found endocrine disturbances in 55.3% (hyperprolactinaemia
31.6%, acropmegaly 4%, Cushing’s syndrome 2.6% hypopituitarism 15.8%,
diabetes insipidus 2.6%.
(1989) in a series of 52 patients found hyperprolactinaemia in 32.7%,
secondary hypogonadism in 7.7%, secondary hypothyrodism in 9.6%, secondary
adrenocorticcal failure in 5.8%, growth hormone deficiency in 25.5%,
panhypopituitarism in 5.6%. Only 31% of the patients were referred for
hypertsecretioon strongly points to the presence of a pituitary adenoma
that is partly necrosed. In cases of mild hyperprolactinaemia delivery of
prolactin inhibiting factor may be inhibited by compression, angulation or
elongation of the pituitary stallk (similar to a pituitary stalk
compression syndrome) was reported in 70% to 76%. In children evaluated
for growth hormone deficiency, primary empty sella varies from 10% to 58%.
Involvement of the
posterior pituitary gland occurs very rarely.
In patients with
evidence of previous hemorrhage the incidence of pituitary insufficiency
is much higher than in those without pituitary apoplexy.
cerebrospinal fluid rhinorrhoea:
The etiology is poorly understood. Considerable proportions of patients
with cerebrospinal fluid rhinorrhoea harbour a pituitary tumour or present
radiologically with an empty sella of normal size or an empty sella
syndrome. Incidence of cerebrospinalfluid rhinorrhoes associated with an
empty sella is reported up to 15%.
Plain skull radiographs:
Empty enlarged sella:
radiographs typically show symmetrical enlargement but maintenance
of the normal configuration of the sella. Sometimes demineralization of
the dorsum sellae, double contour of the sellar floor and signs of erosion
can be observed. All these findings can occur with pituitary tumors.
An area of
hypodensity or decreased attenuation is seen confined to abnormal
sized or enlarged sella turcica on a coronal or horizontal plane. In
some cases the most specific and sensitive modality for diagnosis is
CT scanning employing metrizamide or air contrast.
This is the
investigation of choice, which shows cerebrospinal fluid within the
sella turcica, discrimination of the pituitary stalk, pituitary gland
and optic chiasm, and allows estimation of the degrees of compression,
atrophy, and displacement of the structures.
Sometimes bilateral and
symmetrical lateral shift of the carotid artery can be seen, or descent of
the initial portion of the anterior cerebral artery into the empty sella
turcica occurs occasionally.
Primary as well as
secondary empty sella syndrome is usually benign conditions not requiring
However, in some cases
the clinical and endocrine status necessitates hormonal replacement
therapy. Evidence of pituitary hypersecretion indicates the presence of a
hypersecreting adenoma or remnant or recurrent tumor after surgical
resection or radiotherapy that should be treated accordingly.
disturbances usually are mild and should therefore only be followed
carefully. Surgery should be reserved for cases with progressive
deterioration and radiological evidence of traction or angulation of the
optic nerves and chiasm.
The surgical process of
propping up the optic chiasm was called chiasmopexy. Several
methods are described with good results:
a) Inserting muscle,
carilage, or silicone sponge under the optic chiasm,
b) Packing the sella
with fat, muscle, or cartilage to elevate the pituitary gland, pituitary
stalk and chiasm via the transsphenoidal route,
c) Packing the sella by
transsphenoidal placement of a detachable balloon (Cybulsky 1989),
d) Mortata (1970)
demonstrated improvement of visual field defects in a patient with empty
enlarged sella and descent of
CSF rhinorrhoea may
require prompt surgical intervention since spontaneous obliteration is
unlikely. After appropriate preoperative localization of the fistulous
tract (fluorescein) endoscopic or transsphenoidal closure is the treatment