Pituitary apoplexy

Pituitary apoplexy is an acute clinical syndrome caused by either haemorrhage or infarction of the pituitary gland ². Although variable, it typically comprises of headache, visual deficits, ophthalmoplegia, and altered mental status ⁷. An existing pituitary macroadenoma is usually present (60 - 90%) but it can occur with healthy glands in few isolated cases. 

Epidemiology

The demographics generally follows that of pituitary macroadenomas. Additional predisposing factors include ² :

• medical treatment of a prolactinoma (especially with bromocriptine) ⁶ 
• prior irradiation of the mass
• pregnancy (Sheehan syndrome)
• cerebral angiography
• trauma and surgery
• anticoagulation
• changes in intracranial pressure

Clinical presentation

As the gland suddenly enlarges it may cause compression of structures adjacent to the sella, and thus lead to a number of signs and symptoms, including ⁷:

• sudden headache
• loss of visual acuity with a chiasmal field defect
• oculomotor palsies

In addition, the patient may experience decreased level of consciousness, hypopituitanism, Addisonian crisis ³ and subarachnoid irritation, the latter being secondary to haemorrhage.

Radiographic features

CT

Routine CT is insensitive to the diagnosis unless frank intracranial haemorrhage is present. The pituitary mass may be evident and be hyperdense. Fluid / fluid levels may also be evident. 

MRI

MRI typically demonstrates a pituitary region mass.

• T1 : hyperintense due to blood (see ageing blood on MRI)
• T2 : variable signal
• T1 C+ (Gd) :
  
  • enhancement variable and may be difficult to identify due to intrinsic high T1 signal
• DWI : restricted diffusion may be present in solid infarcted components ⁴

Treatment and prognosis

Provided very prompt neurosurgical intervention is available, to decompress the gland, typically with a transphenoidal approach then prognosis is good. Without surgery the majority of patients perish. Occasionally conservative management may chosen is selected cases. This is usually associated with irreversible hypopituitarism as well as often ophthalmoplegia and visual loss ⁵.

Differential diagnosis

The differential is broadly that of a pituitary region mass, but as these patients present acutely with acute or subacute blood products, it can usually be limited to pituitary region masses with intrinsic high T1 signal.  

• necrotic / haemorrhagic pituitary macroadenoma
  • appearances are the same, but patients do not present acutely
  • whether or not the term apoplexy can be used in subacute presentations is debatable
• craniopharyngioma (adamantinomatous type)
  • calcification in 90%
  • usually in children
  • usually not acute presentation
• Rathke cleft cyst
  • usually asymptomatic
  • no associated mass
  • spherical
• dermoid / teratoma
  • usually will have a fat component
  • unless ruptured, presentation is usually insidious 
  • if ruptured locules of fat density material are often seen in the subarachnoid space