Pituitary apoplexy

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Pituitary apoplexy

Pituitary apoplexy is a clinical syndrome resulting from acute haemorrhage or infarction of the pituitary gland. It is potentially life-threatening and is characterized by the sudden onset of headache, vomiting, visual disturbance, ophthalmoplegia, and altered consciousness. This constellation of findings occurs primarily in patients with pre-existing pituitary adenomas and can be due to extensive tumour infarction or haemorrhage. The term has also been used to describe spontaneous infarction and haemorrhage within a nontumorous pituitary gland with similar clinical effects. The age range of occurrence is broad, from the first to the ninth decade. The incidence of pituitary apoplexy presenting with classic symptoms is reported to be in the order of 0.6 to 9.1% of surgically treated pituitary adenomas. However, clinically silent pathological evidence of pituitary haemorrhage (‘subclinical pituitary apoplexy’) has been reported in up to 25% of surgically removed pituitary adenomas. The clinical syndrome of pituitary apoplexy usually evolves fully within hours to 2 days and its pathophysiology remains uncertain. Predisposing factors for pituitary apoplexy include major surgery, warfarin, aspirin, arterial hypertension, oral contraceptive pill, gonadotropin-releasing hormone analogue, dynamic pituitary function tests, and head trauma. A variety of pituitary tumours, both endocrinologically active and inactive, have been documented in association with pituitary apoplexy, but opinions differ as to whether there is a predominance of a particular type of pituitary tumour. Following apoplexy, hypofunctioning (partial or complete) of normal pituitary tissue appears to be the rule. Hyponatraemia, noted in 44% of patients, may be caused either by inappropriate antidiuretic hormone secretion, hypocortisolism, or hypothyroidism or by a combination of these. MRI is the radiological investigation of choice; in the first 3 to 5 days, haemorrhage within the sella is isointense or hypointense on T 1-weighted images and hypointense on T 2-weighted sequences. When pituitary apoplexy is suspected, the initial management consists of close monitoring of fluid and electrolyte balance coupled with immediate replacement of deficient hormones, in particular corticosteroids. Although not widely accepted, it has been suggested that in patients with visual field or visual acuity defects, surgical decompression should be performed as soon as possible, preferably within the first week, as this appears to optimize visual outcome and to improve pituitary function. Following apoplexy, the risk of tumour recurrence is small, but careful follow-up initially with annual imaging is indicated.