PITUITARY APOPLEXY
Although pituitary apoplexy, acute hemorrhage of the pituitary gland, is an uncommon event, it is an endocrine emergency, and prompt diagnosis and treatment are critical. The typical presentation is acute onset of severe headache (frequently described as “the worst headache of my life”); vision loss (the hemorrhagic expansion takes the path of least resistance and extends superiorly and compresses the optic chiasm); facial pain; nausea and vomiting; or ocular nerve palsies (e.g., ptosis, diplopia) caused by impingement of the third, fourth, and sixth cranial nerves in the cavernous sinuses. In addition, patients may have signs of meningeal irritation and an altered level of consciousness. Increased intracranial pressure may result in increasing drowsiness and stupor and may mandate surgical intervention and decompression. Hypothalamic involvement may lead to disorders of sympathetic autoregulation, resulting in dysrhythmia and disordered breathing. Erythrocytes and an increased protein concentration are found in the cerebrospinal fluid of many patients with pituitary apoplexy. This may be a potential source of confusion in differentiating pituitary apoplexy from meningitis or subarachnoid hemorrhage.
The most immediate hormonal
deficiency is secondary adrenal insufficiency, which may lead to hypotension and
adrenal crisis. Pituitary apoplexy occurs most often in the setting of a
preexisting pituitary macroadenoma or cyst, and the hemorrhage may be
spontaneous or triggered by head trauma, coagulation disorders (e.g.,
idiopathic thrombocytopenic purpura), or anticoagulant (e.g., heparin,
warfarin) administration. Rarely, the pituitary tumor apoplexy may be induced
by the administration of a hypothalamic-releasing hormone (e.g.,
gonadotropin-releasing hormone agonist in a patient with a
gonadotropin-secreting adenoma) or by the administration of an agent used to
treat the pituitary tumor (e.g., bromocriptine for a prolactin-secreting
pituitary tumor). The rapid expansion of the sellar contents results in the
immediate mass-effect symptoms. In more than 50% of cases of pituitary
apoplexy, the apoplectic event is the initial clinical presentation of a
pituitary tumor. The risk of pituitary apoplexy is not related to age or
gender.
Pituitary imaging with magnetic
resonance imaging (MRI) is diagnostic and typically shows signs of intra-pituitary or intra-adenoma hemorrhage, fluid–fluid level, and compression of
normal pituitary tissue. Hormonal evaluation typically shows complete anterior
pituitary failure (including prolactin). Because of the anatomy of the
pituitary circulation and the sparing of the infundibular circulation (inferior
hypophysial arteries), the posterior pituitary is infrequently affected by
pituitary apoplexy. Thus, diabetes insipidus is rare in patients with pituitary
apoplexy.
The clinical course of pituitary
apoplexy varies widely in duration and severity. Thus, the appropriate
intervention may be difficult to determine. Treatment is aimed at alleviating or
relieving local compression that compromises adjacent structures such as the
visual individualized pathways.
In addition to anatomic
considerations, the endocrine status of the patient must be considered and
treated accordingly. The timing of therapy must be individualized on the basis
of the symptoms and the severity of the apoplectic event. Neurosurgical
intervention is often the most rapid and effective method of decompressing the sella turcica and the
surrounding structures and is indicated in the event of mental status changes
and other symptoms attributable to increased intracranial pressure. Surgical
decompression is also indicated in the absence of these symptoms when the
visual pathways are compromised to prevent prolonged ischemia leading to
irreversible nerve dysfunction. Although the timing of the surgical
intervention does not seem to affect the recovery of ocular palsies, an
operation within 1 week after apoplexy in a conscious patient whose condition
is stable improves recovery of visual acuity more than an operation performed
with a delay of more than 1 week after the event. Although hemorrhagic areas of
the pituitary are absorbed over time, reabsorption alone may not occur fast
enough for recovery of visual acuity. Therefore, waiting for spontaneous resolution of a visual field defect
in a patient whose condition is otherwise stable may not be optimal management.
In patients with normal visual fields who lack cranial nerve palsies,
observation is a reasonable treatment approach. Stress dosages of
glucocorticoids should be initiated in all patients with pituitary apoplexy.
Pituitary function may not recover, and long-term pituitary target gland
hormone replacement therapy may be needed.
It should be noted that necrosis and
hemorrhage within a pituitary tumor occur much more frequently than the
clinical syndrome of pituitary apoplexy, especially in silent corticotroph
adenomas, in which hemorrhage occurs in more than 50% of the tumors. Overall,
hemorrhage occurs in 10% to 15% of pituitary adenomas, and it is usually
clinically silent.
