Empty sella syndrome

# Overview
Empty sella syndrome (ESS) is defined as herniation of subarachnoid space into the sella turcica (arachnoidocele) in which there is a characteristic radiological finding of "empty sellar space" on magnetic resonance imaging (MRI) and computerized tomography (CT) with a flattened pituitary and elongated stalk. It can be partial if less than 50% of sellar space is filled with cerebro-spinal fluid (CSF), or complete if CSF fills more than 50% of space in the sella and gland thickness is less than 2mm.

# Historical Perspective
- The term empty sella was first used by Bush in 1951 to describe a peculiar anatomical condition, observed in 40 of 788 human cadavers, particularly females, characterized by a sella turcica with an incomplete diaphragm sellae that forms only a small peripheral rim, with a pituitary gland not absent, but flattened in such a manner as to form a thin layer of tissue at the bottom of the sella turcica.
- In ,  mutations were first identified in the pathogenesis of .
- In , the first  was developed by  to treat/diagnose .

# Classification
-  may be classified according to  into  subtypes/groups:
- Other variants of  include , , and .
There are two types of ESS: primary and secondary.
- Primary ESS happens when a small anatomical defect above the pituitary gland increases pressure in the sella turica and causes the gland to flatten out along the interior walls of the sella turica cavity. Primary ESS is associated with obesity and high blood pressure in women. The disorder sometimes results in a build-up of fluid pressure inside the skull and the pituitary gland may be smaller than usual.
- Secondary ESS is the result of the pituitary gland regressing within the cavity after an injury, surgery, or radiation therapy. Individuals with secondary ESS due to destruction of the pituitary gland have symptoms that reflect the loss of pituitary functions, such as the ceasing of menstrual periods, infertility, fatigue, and intolerance to stress and infection.

# Pathophysiology
- The pathogenesis of  is characterized by , , and .
- The  gene/Mutation in  has been associated with the development of , involving the  pathway.
- On gross pathology, , , and  are characteristic findings of .
- On microscopic histopathological analysis, , , and  are characteristic findings of .
In children, ESS may be associated with early onset of puberty, growth hormone deficiency, pituitary tumors, or pituitary gland dysfunction. MRI scans are useful in evaluating ESS and differentiating it from other disorders that produce an enlarged sella.

# Clinical Features

# Differentiating  from other Diseases
-  must be differentiated from other diseases that cause , , and , such as:
- Autoimmune factors
- Cavernous sinus thrombosis
- Communicating hydrocephalus
- Congenital absence of the diaphragma sellae
- Diabetes Mellitus
- Familial
- Head trauma
- Increased intracranial pressure
- Radiation therapy complication
- Meningitis
- Pituitary adenoma
- Primary in middle-aged obese women
- Rupture of intrasellar or parasellar cyst
- Sheehan's Syndrome
- Surgery
- Vascular diseases

# Differentiating Empty sella syndrome from other diseases:
Empty sella syndrome needs to be differentiated from other diseases causing hypopituitarism.

# Epidemiology and Demographics
- The prevalence of  is approximately  per 100,000 individuals worldwide.
- In , the incidence of  was estimated to be  cases per 100,000 individuals in .

## Age
- Patients of all age groups may develop .
-  is more commonly observed among patients aged  years old.
-  is more commonly observed among .

## Gender
-  affects men and women equally.
-  are more commonly affected with  than .
- The  to  ratio is approximately  to 1.

## Race
- There is no racial predilection for .
-  usually affects individuals of the  race.
-  individuals are less likely to develop .

# Risk Factors
- Common risk factors in the development of  are , , , and .

# Natural History, Complications and Prognosis
- The majority of patients with  remain asymptomatic for .
- Early clinical features include , , and .
- If left untreated,  of patients with  may progress to develop , , and .
- Common complications of  include , , and .
- Prognosis is generally , and the  of patients with  is approximately .

# Diagnosis
Patient #1: MR images demonstrate an expanded and empty sella

## Diagnostic Criteria
- The diagnosis of  is made when at least  of the following  diagnostic criteria are met:

## Symptoms
-  is usually asymptomatic.
- Symptoms of  may include the following:

## Physical Examination
- Patients with  usually appear .
- Physical examination may be remarkable for:

## Laboratory Findings
- There are no specific laboratory findings associated with .
- A    is diagnostic of .
- An  concentration of   is diagnostic of .
- Other laboratory findings consistent with the diagnosis of  include , , and .

## Imaging Findings
- There are no  findings associated with .
-  is the imaging modality of choice for .
- On ,  is characterized by , , and .
-  may demonstrate , , and .

## Other Diagnostic Studies
-  may also be diagnosed using .
- Findings on  include , , and .

# Treatment

## Medical Therapy
- There is no treatment for ; the mainstay of therapy is supportive care.
- The mainstay of therapy for  is  and .
-  acts by .
- Response to  can be monitored with  every .

## Surgery
- Surgery is the mainstay of therapy for .
-  in conjunction with  is the most common approach to the treatment of .
-  can only be performed for patients with  .

## Prevention
- There are no primary preventive measures available for .
- Effective measures for the primary prevention of  include , , and .
- Once diagnosed and successfully treated, patients with  are followed-up every . Follow-up testing includes , , and .