Acute Pituitary Failure

Synonyms: Pituitary Apoplexy, Hypopituitary Coma

• Acute pituitary failure is a rare condition which occurs most often in patients with pituitary tumours.
• It is characterised by the sudden onset of hormonal dysfunction often with important accompanying symptoms.
• It is usually caused by haemorrhage or infarction of the pituitary gland and a variety of pathophysiological processes may cause this.
• It occurs with pituitary apoplexy when it is usually accompanied by a pituitary tumour.
• It can occur in Sheehan syndrome where there is no pituitary gland tumour.
• It is a rare life-threatening condition of sudden onset which is both difficult to diagnose and treat.

• This usually occurs because of an acute expansion of a pituitary adenoma. Less often it occurs from haemorrhage or infarction in a nonadenomatous gland. These changes compromise the unusual blood supply of the anterior pituitary and pituitary stalk.
• It can occur in otherwise healthy patients where the pituitary gland is damaged by trauma, surgery or haemorrhage.
• It may be associated with an acute medical episode such as hypertension, diabetes mellitus, bleeding disorders, infection, trauma, hypothermia, or sedative therapy.
• It may be precipitated by medical interventions such as endocrine stimulation tests, treatment with bromocriptine, surgery¹ and pituitary irradiation.

• Acute pituitary failure is rare. It :
  • Occurs in between 1 and 10% of pituitary tumours.
  • Occurs twice as often in men, usually between age 37 and 57 years.
• Postpartum pituitary necrosis is the most common cause of hypopituitarism but:
  • This usually presents progressively with a variety of developing symptoms (starting commonly with failure to lactate, breast involution and then amenorrhoea), rather than the more dramatic and acute presentation.
  • The more dramatic acute presentation of pituitary apoplexy only occurs in a minority of patients with Sheehan syndrome.
  • Sheehan syndrome occurs in as many as 1-2% of women with a significant postpartum haemorrhage apart from cases developing at other stages of pregnancy and the puerperium.

History

The onset of symptoms is sudden and may occur in patients known to have a pituitary adenoma.

• Headache occurs in 95% of patients. It often starts suddenly^3,4 as a unilateral, retro-orbital headache before becoming more generalised. It is thought to be caused by stretching of the dura mater in the sella.⁵
• Vomiting occurs in 69% of cases. It often accompanies the headache and may be caused by elevation of intracranial pressure or irritation of meninges.
• Diplopia may occur in the conscious patient from involvement of different cranial nerves.
• Visual field defects occur in 64% of patients, by compression of the optic chiasm. Defects in acuity may result from optic nerve compression.
• Ptosis may occur.

Examination findings

There may be rapid progression to coma suggesting stroke, subarachnoid and with accompanying meningism, even meningitis. Careful and early examination may detect a variety of findings. These may include:

• Bitemporal superior quadrantic field defect is classic. There may be a contralateral homonymous hemianopia if the optic chiasm is affected differently.
• Compression of the cavernous sinus may impair cranial nerves III, IV and VI causing ocular paresis and hence diplopia (in the conscious patient).
• Horner syndrome may develop if sympathetic fibres are damaged.
• Stroke can occur if the carotid syphon is compressed against the anterior clinoid process. This may be associated with meningism, stupor and coma.
• Thermal regulation may be impaired by hypothalamic involvement. Hypothermia can result.
• Endocrine deficiencies can result from destruction of adenohypophyseal tissue.
• Complete ophthalmoplegia may result.⁶
• More difficult to diagnose is the pituitary apoplexy which can arise from ectopic pituitary adenomas. These are usually found at autopsy.

• Subarachnoid haemorrhage⁷
• Meningitis
• Brain tumours
• Demyelinating disease
• Cerebrovascular disease

• Blood tests:
  • Urea and electrolytes
  • Creatinine
  • Blood glucose urgently (risk of hypoglycaemia)
  • Pituitary hormones
• Imaging to assess the pituitary:
  • CT scan
  • Magnetic resonance imaging (MRI) is preferable to visualise haemorrhage not seen on CT scans

Acute management

This is one of a small but important group of endocrine emergencies. It is so rare that there is little evidence on which to plan optimum care.⁹

• Resuscitation and stabilisation of the patient with particular attention to management of fluids.
• High dose corticosteroids (hypopituitarism is usual).
• Hormonal treatment of any adrenocortical hormone deficiency.
• Surgical decompression of pituitary may be required.¹⁰
• Some patients can be managed conservatively.^11,9

Long term management

Patients should be followed up for:

• Regrowth of tumour
• Endocrine abnormalities^9,12

It is a life threatening condition with a high mortality. It is difficult to diagnose and difficult to treat.^10,11 However with rapid diagnosis followed by prompt correct management it is possible to achieve complete recovery.^13,12