Anesthesia for Pituitary Surgery
Anesthesia for pituitary surgery is challenging because of the diverse endocrinological abnormalities associated with the disease process. Close collaboration is required between anesthesiologists, neurosurgeons, and endocrinologists during the perioperat
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Fauzia Khan and Faraz Shafiq
18.1 Introduction Anesthetic management for pituitary surgery demands a thorough knowledge of anatomy, endocrinology and pathophysiology of pituitary gland as well as a multidisciplinary approach involving endocrinologists, anesthesiologists, and neurosurgeons. Preoperative assessment should focus on the identification of hormonal and metabolic disturbances and planning the intraoperative care based on this. The postoperative period requires careful monitoring in the recovery units and close collaboration between the teams. The aim of this chapter is to review the key concepts required for safe conduct and perioperative management of patients requiring pituitary surgery, and an update on its current management.
18.2 R eview of Anatomy and Physiology The pituitary gland (Fig. 18.1) is approximately 8 mm in diameter and lies in the middle cranial fossa at the base of skull in a cavity of the F. Khan (*) • F. Shafiq Department of Anaesthesiology, Aga Khan University, P O Box 3500, Stadium Road, Karachi 74800, Pakistan e-mail: [email protected]
sphenoid bone (sella turcica). The gland is surrounded by the bone in its anterior, posterior and inferior aspects. The optic chaisma lies superiorly and is separated from the pituitary by a sheet of dura known as “diaphragma sellae”. The lateral relationship has internal carotid artery, cavernous sinus along with the third, fourth and sixth cranial nerves [1].
18.3 Pathophysiology The pituitary gland consists of two lobes. The larger anterior lobe, (adeno-hypophysis) secretes several hormones as shown in Table 18.1. The posterior lobe (neuro-hypophysis) is responsible for secretion of antidiuretic hormone (ADH) and oxytocin. The gland is connected through a fold of dura to the hypothalamus, which regulates the hormones secreted by the anterior pituitary, by several hypothalamic releasing and inhibiting factors. The factors released by hypothalamus are thyrotropin-releasing hormone (TRH), corticotropin-releasing hormone (CRH), gonadotropin-releasing hormone (GnRH), growth hormone (GHRH), and prolactin- releasing hormone (PRLH). The control of posterior pituitary hormone ADH is through plasma osmolality and the circulating blood volume, whereas suckling reflex stimulates oxytocin release.
© Springer International Publishing Switzerland 2017 Z.H. Khan (ed.), Challenging Topics in Neuroanesthesia and Neurocritical Care, DOI 10.1007/978-3-319-41445-4_18
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F. Khan and F. Shafiq
214 Fig. 18.1 Diagrammatic representation showing the suprasellar and parasellar anatomical relationship of the pituitary gland through the endoscopic approach
Optic Chiasma Pituitary stalk Pituitary gland Internal carotid artery
Clivus
Foramen lacerum
Eustachian tubes
Floor of sphenoidal sinus
Soft palate
Table 18.1 Hormones and functions of pituitary gland Hormones secreted by anterior pituitary Thyroid-stimulating hormone (TSH) Adrenocorticotrophic hormone (ACTH) Melanocyte-stimulating hormone (MSH) Follicle-stimulating hormone (FSH) Lute
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