Get Adobe Flash player
Pituitary Disorders Congenital Growth Hormone Deficiency – A Review with a Focus on Neuroimaging Sarah L Tsai 1 and Eoghan Laffan 2 1. Paediatric Endocrinologist and Assistant Professor of Paediatrics, Section of Endocrinology and Diabetes, Children’s Mercy Hospital and Clinics, University of Missouri Kansas City School of Medicine, Kansas City, Missouri, US; 2. Consultant Paediatric Radiologist, Children’s University Hospital, Dublin, Ireland Abstract Growth hormone deficiency is an important cause of short stature in childhood. It is characterised by low growth velocity in childhood and is diagnosed by stimulation testing. Individuals with growth hormone deficiency may have other pituitary hormone deficits in addition to growth hormone deficiency. When multiple pituitary hormone deficiencies are present, abnormal pituitary anatomy, as visualised on magnetic resonance imaging (MRI), is a frequent finding. The classic triad (ectopic posterior pituitary, hypoplastic or aplastic anterior pituitary and absent/thin pituitary stalk) or variants of the classic triad are commonly seen in these patients. Volumetric sequencing allows all three planes of visualisation to be reconstructed in post-processing, allowing the radiologist to more fully evaluate pituitary anatomy. The normal dimensions of the pituitary gland vary by age and precise definitions of what constitutes a hypoplastic gland are not clearly defined in the medical literature. Having an experienced neuroradiologist interpret the MRI in patients with pituitary dysfunction is very important. Keywords Growth hormone deficiency, panhypopituitarism, pituitary, magnetic resonance studies, empty sella Disclosure: The authors have no conflicts of interest to declare. Received: 17 May 2013 Accepted: 14 June 2013 Citation: European Endocrinology, 2013;9(2):136–40 Correspondence: Sarah L Tsai, Section of Endocrinology and Diabetes, Children’s Mercy Hospital and Clinics, University of Missouri Kansas City School of Medicine, 2401 Gillham Road, Kansas City, MO 64108, US. E: Growth hormone deficiency (GHD) causes low growth velocity in childhood, and if left untreated, severe short stature in adulthood. It is diagnosed by examining auxological data, thorough clinical examination and provocative testing. Patients with congenital GHD may have other pituitary hormone abnormalities and abnormal pituitary anatomy. Rathke’s pouch moves up from the oral cavity and comes in contact with the posterior pituitary (also known as the neurohypophysis). The posterior pituitary arises from an evagination of the ventral hypothalamus and the third ventricle. Remnants of Rathke’s pouch may persist and lead to colloid cysts or craniopharyngioma. 4,5 Magnetic resonance imaging (MRI) is the best tool in delineating pituitary anatomy and pathology. On MRI, patients with congenital hypopituitarism may have the ‘classic triad’ of pituitary stalk interruption syndrome, which consists of: (a) an interrupted or thin pituitary stalk; (b) an absent or ectopic posterior pituitary (EPP); and (c) anterior pituitary hypoplasia or aplasia 1 see Figures 1–3 for examples. Approximately 50% of patients with idiopathic GHD have been shown to have abnormal pituitary anatomy on MRI. 2,3 MRI is an important marker for the anticipation of future endocrine dysfunction, as patients with abnormal pituitary anatomy are more likely to have multiple endocrinopathies. 3 The pituitary gland is encased in the sphenoid bone at the base of the skull in the sella turcica (‘Turkish saddle’). The diaphragma sellae prevents the cerebrospinal fluid (CSF) from entering the sella turcica. If the diaphragma sellae does not form properly, this can allow CSF to enter the sella turcica and compress the pituitary, giving the appearance of ‘empty sella syndrome’. 5 When this occurs, the pituitary tissues do not retain a normal appearance and the function of the gland may or may not be affected. CSF rhinorrhea or visual field abnormalities have been described in patients with ‘empty sella syndrome’. See Figure 4 for example of empty sella syndrome secondary to intracranial mass. The Pituitary Gland – A Physiological Overview The hypothalamus and the pituitary gland function as a ‘control centre’ for several endocrine glands, including the thyroid, adrenals and gonads. The human foetal anterior pituitary is recognisable at four to five weeks gestation, and the hypothalamic–pituitary unit is mature at 20 weeks. 4 The anterior pituitary (also known as the adenohypophysis) originates from Rathke’s pouch, which is an extension of the oral ectoderm. The 136 The anterior pituitary gland has a very rich blood supply. Arterial blood is supplied from the internal carotid arteries via the superior, middle and inferior hypohysial arteries. The pituitary stalk and the posterior pituitary are supplied directly from branches of the middle and inferior hypophysial arteries. 4 Anterior pituitary cells are classified into four cell types based on their secretory products. Somatotrophs secrete GH and account for 50  % of adenohypophysial cells. 4 GH stimulates production of insulin-like © Touch ME d ica l ME d ia 2013