Pituitary Apoplexy

Abstract

Pituitary apoplexy is traditionally defined as acute hemorrhagic infarction of the pituitary gland. Although uncommon, it can be a serious condition requiring emergency treatment. In the majority, the pituitary hemorrhage occurs in a preexisting mass like a pituitary adenoma or a Rathke cleft cyst. It can evolve over 1 or 2 days with sudden onset of severe retro-orbital headache accompanied by neurological and endocrinological deterioration. Visual disturbances are particularly common with occasional trigeminal nerve symptoms and Horner syndrome. Acute hypocortisolism is common leading to nausea and severe systemic hypotension. Prompt recognition, ensuring hemodynamic stability, and replacement of cortisol and other hormones in consultation with an endocrinologist is the cornerstone of management. In an unstable or deteriorating patient with severe or worsening ophthalmic signs and reduced level of consciousness, the pituitary hemorrhage needs surgical decompression.

Keywords

Acute hemorrhagic infarction of pituitary gland, Acute hypocortisolism, Endocrine and neurosurgical emergency, Ophthalmoplegia and bitemporal superior quadrantanopia, Precipitating factors associated with pituitary apoplexy, Sheehan syndrome

Outline
Clinical Features 395
Management 395
References 397

Pituitary failure, or hypopituitarism, is a condition in which the pituitary gland fails to meet the normal demands of the body and the production of at least one of its hormone is inadequate. Among the myriad causes of hypopituitarism, pituitary apoplexy is an uncommon, but significant cause of failure with unacceptably high morbidity if the management is delayed.

Pituitary apoplexy is traditionally defined as the abrupt and occasionally catastrophic occurrence of acute hemorrhagic infarction of the pituitary gland. Although uncommon, it can be a serious condition requiring emergency treatment. First described in 1898 by Bailey, it was named by Brougham et al. in 1950. Although the glandular bleed and infarction lead to significant pituitary damage including damage to the surrounding sellar structures, silent small microinfarcts are seen in up to 5% of random autopsies.

Spontaneous hemorrhage into a pituitary adenoma can result in apoplexy and is a complication in 1–2% of all pituitary adenomas. In the majority, the pituitary hemorrhage occurs in a preexisting mass like an adenoma or Rathke’s cleft cyst, but it may be seen in a normal gland. Apoplexy can sometimes be the first manifestation of an underlying adenoma. It has been described after head trauma and skull base fracture and can be associated with diabetes mellitus, hypertension, hypovolemic shock, and sickle cell anemia.

Estrogenic stimulation during pregnancy causes the pituitary gland to become vascular and enlarged. Such a vascularized gland is susceptible to arterial pressure changes and hemorrhage. Although less commonly encountered in the developed world, Sheehan syndrome can still be seen in the medically underserved nations where modern obstetric care is lacking. It is classically described after severe postpartum hemorrhage resulting in adenohypophyseal vessel spasm and pituitary necrosis. Some authors consider it to be distinct from pituitary apoplexy as the gland although enlarged, remains nonhemorrhagic in many cases of Sheehan syndrome. Pituitary autoimmunity may have a role in gland failure after postpartum hemorrhage. The clinical presentation can vary from hypovolemic shock to gradual onset of partial to complete pituitary failure over months to years. The classic symptoms of Sheehan syndrome are postpartum amenorrhea and inability to nurse.

Fig. 23.1 illustrates the magnetic resonance image of brain of a patient with pituitary apoplexy. The hyperintense mass in T1 weighted image is pituitary hemorrhage with suprasellar extension compressing the optic chiasm. Table 23.1 lists the etiologies that can be associated with pituitary apoplexy.

Table 23.1

Precipitating Factors Associated With Pituitary Apoplexy

Reproduced from Anaesthesia and Intensive Care , with the kind permission of the Australian Society of Anaesthetists.

(1) Stimulation of Pituitary Gland or Tumor

•

Estrogen therapy or high estrogen states like pregnancy and peripartum period; oral contraceptive pill use
•

Infertility treatment with clomiphene
•

Treatment or withdrawal of dopamine analogs like bromocriptine or cabergoline
•

Abrupt withdrawal of corticosteroid therapy
•

Dynamic functional testing of the pituitary with thyrotropin-releasing hormone, corticotrophin-releasing hormone, hypothalamic-releasing hormone, gonadotropin-releasing hormone, insulin-releasing and luteinizing hormone-releasing hormone
•

Treatment with gonadotrophin-releasing hormone analogs for prostatic cancer or ovarian stimulation

(2) Major Surgery

•

Cardiac surgery
•

Pituitary surgery
•

Abdominal aortic aneurysm repair
•

Adrenalectomy
•

Hip and knee joint replacement as well as spinal surgery
•

Large-volume liposuction
•

Orchiectomy

(3) Abnormal Coagulation States

•

Anticoagulation or dialysis
•

Thromboprophylaxis
•

Thrombolysis
•

Severe liver disease
•

Aspirin or warfarin therapy
•

Thrombocytopenia
•

Factor V Leiden mutation
•

Pregnancy

(4) Factors Affecting Intracranial Pressure

•

Coughing and sneezing
•

Mechanical ventilation
•

Spinal and general anesthesia, head trauma, and procedures such as angiography, myelography, pneumoencephalography

(5) Miscellaneous