The term empty sella is referred to intrasellar herniation of suprasellar arachnoid and cerebrospinal fluid (CSF) of subarachnoid space, resulting in flattening of the pituitary gland (1). An anatomic defect in the sellar diaphragm has been found in up to 50% of adults and the overall incidence of an empty sella on imaging has been estimated at 12% (2, 3). Empty sella is defined as partial or total when less or more than 50% of the sella is filled with CSF respectively, with the gland thickness being < 2 mm in the latter case (fig. 1) (1). The widespread use of computed tomography (CT) and magnetic resonance imaging (MRI) has made empty sella a common incidental finding. According to data obtained from autopsies and neurological studies, the presence of empty sella ranges from 5.5 to 38% with female to male ratio of 4 to 1 (4). Two types of empty sella should be distinguished. Secondary empty sella (SES) may be caused by pituitary adenomas either undergoing spontaneous shrinkage or more often after medical treatment, surgery or radiation therapy. The image of empty sella may be also a result of a regression of an inflammatory lesions of a pituitary gland such as lymphocytic and granulomatous hypophysitis (4, 5). When no apparent cause of the herniation of subarachnoid space is present (such as surgery, radiotherapy or medical medical treatment for an intrasellar tumor) it is a primary empty sella (PES). Several etiopathogenic hypotheses have been introduced, including a congenital incomplete formation of the sellar diaphragm (1). Moreover, the empty sella has been associated with elevated intracranial pressure (ICP), posteriorly placed optic chiasm and a reduction in pituitary gland volume due to menopause, multiparity, pituitary gland infarction, obesity or dopamine agonists and somatostatin analogs treatment (6). Chronically transmitted CSF pulsations from the herniated subarachnoid space can results in bony expansion and remodeling of the sella turcica. On the other hand the empty sella is the most commonly described imaging sign in the setting of idiopathic intracranial hypertension (also known as pseudotumor cerebri) and presumably there is a correlation between the flattening of the pituitary gland and chronically elevated ICP. On MRI , the empty sella is shown by varying degrees of flatteing of the superior surface of the pituitary gland, elongated pituitary stalk and by CSF-intensity signal within the sella and is often associated with enlargement and remodeling of bony sella (7). Empty sella may be a radiological finding in asymptomatic patients, but it may be also associated with numerous disorders such as neurological, visual and endocrine.

The aim of the study was to retrospectively review the data of patients with empty sella on MRI hospitalized during one year in the Department of Endocrinology of The Centre of Postgraduate Medical Education in Bielański Hospital. We evaluated clinical characteristics, pituitary function and radiological features, with a detailed analysis of the magnetic resonance imaging of the pituitary-hypothalamic region results.

We retrospectively reviewed the electronic medical records of patients hospitalized in the Department of Endocrinology in Bielański Hospital between September 2012 and September 2013 searching for the patients with the ICD-10 codes: D35.2 (benign neoplasm of pituitary gland) and E23. That included patients with following codes: E23.0 (hypopituitarism), E23.1 (iatrogenic hypopituitarism), E23.2 (diabetes insipidus), E23.6 (other disorders of pituitary gland). We found of 300 of such and then we searched their electronic and paper documentation to find the cases with the diagnosis of empty sella. The results of current magnetic resonance imaging of pituitary-hypothalamic region were analyzed and 40 patients had empty sella present. We estimated the pituitary height on MRI in all cases. We collected data on the age, sex, BMI, causes of empty sella and results of hormonal and ophthalmological evaluation (if available). Basal endocrine evaluation was performed in most patients: TSH, free T4, ATPO, ACTH, cortisol, LH, FSH, estradiol, testosterone (men), PRL, GH, IGF-1 (age and gender adjusted). Dynamic tests were performed to evaluate the gonadotropic axis if necessary.

From September 2012 to September 2013 one thousand seven hundred twenty four patients with numerous endocrine disorders were hospitalized in the Department of Endocrinology in Bielański Hospital. Among them we found 40 patients with an empty sella on MRI which constituted 2.3% of all hospitalized patients in the Department of Endocrinology.