https://www.youtube.com/watch?v=1exN1kFX2wI
Anatomy and vascularization of the pituitary gland: a | The pituitary gland is located in the sphenoid bone (sella turcica) and is composed of the anterior lobe (adenohypophysis) and the posterior lobe (neurohypophysis). The anterior lobe is composed of three parts: the pars distalis, which is the main component of adenohypophysis that secretes anterior pituitary hormones; the pars intermedia, which is suppressed in humans; and the pars tuberalis, which surrounds the infundibulum. The optic chiasma (where the optic nerves cross) is located on top of the superior part of the pituitary gland. b | The infundibulum, median eminence, pars tuberalis and posterior lobe are supplied by the internal carotid artery, whereas the pars distalis receives most of its blood supply from venous drainage from the infundibulum and the posterior lobe of the pituitary gland. The venous blood supply makes the anterior pituitary gland vulnerable to disturbances in blood supply.
Part b courtesy of M. E. Aykurt, Erciyes University, Kayseri, Turkey.
Radiological characteristics of Sheehan syndrome: a,b | Acute phase. Post-contrast MRI scans of the pituitary gland in a patient 2 months after postpartum haemorrhage showing gland atrophy and non-haemorrhagic central infarction characterized by central hypointensity on T1-weighted images (part a) and hyperintensity on T2-weighted images (part b). c,d | Chronic phase. Coronal (part c) and sagittal (part d) T1-weighted MRI scans showing an empty sella turcica. Sella turcica size is normal in all images. Arrows indicate the pituitary gland.
Karaca, Z., Laway, B., Dokmetas, H. et al. Sheehan syndrome. Nat Rev Dis Primers 2, 16092 (2016). https://doi.org/10.1038/nrdp.2016.92
Sheehan syndrome or postpartum hypopituitarism is a condition characterized by hypopituitarism due to necrosis of the pituitary gland. The initial insult is caused by massive postpartum haemorrhage (PPH), leading to impaired blood supply to the pituitary gland, which has become enlarged during pregnancy. Small sella turcica size, vasospasms (caused by PPH) and/or thrombosis (associated with pregnancy or coagulation disorders) are predisposing factors; autoimmunity might be involved in the progressive worsening of pituitary functions. Symptoms are caused by a decrease or absence of one or more of the pituitary hormones, and vary, among others, from failure to lactate and nonspecific symptoms (such as fatigue) to severe adrenal crisis. In accordance with the location of hormone-secreting cells relative to the vasculature, the secretion of growth hormone and prolactin is most commonly affected, followed by follicle-stimulating hormone and luteinizing hormone; severe necrosis of the pituitary gland also affects the secretion of thyroid-stimulating hormone and adrenocorticotropic hormone. Symptoms usually become evident years after delivery, but can, in rare cases, develop acutely. The incidence of Sheehan syndrome depends, to a large extent, on the occurrence and management of PPH. Diagnosis is based on clinical manifestations combined with a history of severe PPH; hormone levels and/or stimulation tests can confirm clinical suspicion. Hormone replacement therapy is the only available management option so far.
Sheehan syndrome. Nat Rev Dis Primers 2, 16093 (2016). https://doi.org/10.1038/nrdp.2016.93
