Pituitary apoplexy describes a condition in which the pituitary gland is subject to necrotic changes that may or may not be due to hemorrhage. Pituitary apoplexy has a variable presentation, although it most commonly presents with headaches, visual changes, changes in consciousness and ophthalmoplegia.
Patients most frequently present with a sudden, severe retro-orbital headache, although the disease manifestations are very variable and may be completely asymptomatic . Several mechanisms responsible for the headache have been suggested and they include irritation of the meninges and the superior division of the trigeminal nerve within the cavernous sinus, compression of the dura mater and sellar wall enlargement. The headache may progress by becoming generalized, although there is no necessary association with subarachnoid hemorrhage. The growth of the tumor is restricted to the sella turcica.
In addition to headaches, pituitary apoplexy can also present with confusion, vomiting, nausea and visual changes. Visual field defects and the decrease in visual acuity are generally caused by compression of the optic tracts, chiasma, and the optic nerves. In addition, other cranial nerves that course through the cavernous sinus can also be affected, in particular, cranial nerves III, IV, and VI with resulting diplopia. This is generally the result of sudden hemorrhage and necrosis in the lateral pituitary fossa, leading to the displacement of the oculomotor nerves. Cranial nerve III involvement results in ipsilateral mydriasis and ptosis whereas cranial nerve V irritation may lead to facial numbness .
20% of patients will exhibit altered mental status. This is a particularly worrisome sign and can signal rapid deterioration. It can initially manifest with insignificant lethargy and progress to stupor or coma.
MRI is the diagnostic modality of choice whenever there is a reasonable suspicion of pituitary apoplexy. Sensitivity is around 90% and the modality can identify the presence of hemorrhage or infarction . MRI can also distinguish between the two phenomena and indicate the approximate duration of the apoplexy, depending on the sequences taken. CT is another option although it is not as reliable as MRI and is usually only utilized when MRI cannot be performed due to the patient's claustrophobia or the presence of implants that contain metallic elements. Around 25% of all tumors will show evidence of bleeding and infarction on MRI, but this is insufficient to diagnose pituitary apoplexy when symptoms are not present concomitantly .
A CSF analysis may be necessary to rule out other potential causes of the presenting symptoms such as subarachnoid hemorrhage or meningitis. This is done by performing a lumbar puncture under local anesthesia. Most frequently, CSF analyses is normal in pituitary apoplexy although some cases exhibit increased red blood cells if the blood from pituitary hemorrhage entered the subarachnoid space. An MRI with a contrast agent can then distinguish completely between a subarachnoid hemorrhage and pituitary apoplexy. It will show aneurysms of cerebral vessels and identify the potential cause for subarachnoid hemorrhage.
A battery of blood tests has to be performed to confirm the diagnosis if there is a reasonable suspicion of pituitary apoplexy. They include a CBC (complete blood count), LFTs (liver function tests), renal function tests (urea and creatinine), electrolyte serum levels and coagulation testing. In addition, serum levels of hormones such prolactin, LH (luteinizing hormone), FSH (follicle-stimulating hormone), TSH (thyroid-stimulating hormone), T3/T4 (thyroid hormones), growth hormone and IGF-1 are measured .
Finally, it is critical to assess visual field function directly after the condition is diagnosed . This allows the quantification of the damage to the optic nerve and may influence the decision to perform surgery.
It is critically important to stabilize the vascular system after pituitary apoplexy is diagnosed. This may entail admission to the intensive care unit if circulatory collapse is feared or suspected . Severe fall in blood pressure can be caused by the deficiency of cortisol associated with the disease.
Pituitary apoplexy is associated with adrenal insufficiency. The latter is commonly treated with intravenous infusions of saline and dextrose. More than two liters may be administered in affected adults. Hydrocortisone is subsequently administered either intravenously or intramuscularly . Dexamethasone is another corticosteroid medication that can be potentially utilized, although its use is not recommended unless there is significant brain swelling in the presence of hemorrhage. Not all patients will require corticosteroid supplementation. If the clinical picture is appropriate, cortisol levels can be measured every morning at 9:00 AM. Hormone replacement is then initiated only if cortisol serum levels are below 550 nmol/L.
Surgical treatment is particularly dependent on visual symptoms and altered mental status. Surgery is generally recommended if there is severe loss of visual acuity, severe or worsening visual field defects or if there is a gradual decline in the mental status of the patient. Surgery is performed through the transsphenoidal route, in which instruments are passed into the nose and the sphenoid bone is punctured for access into the pituitary gland. Surgery is generally beneficial if it is performed within a week of symptom onset or in the presence of residual vision.
On the other hand, conservative treatment is recommended in patients with mild visual changes or double vision. The overall level of consciousness, blood test results and the function of the visual system need to be closely assessed and followed up. Surgery would still be indicated if there is subsequent deterioration in function after treatment is initiated or if the response does not live up to expectations. Dopamine agonists are an option in case apoplexy occurs in a prolactin-secreting tumor.
Follow up with an endocrinologist is recommended after recovery takes place. Recommendations include an MRI every 3 to 6 months initially and then yearly. Neoplastic tissue that remains after surgical treatment can be treated with another surgical operation, medication, or "gamma knife" radiation therapy.
Surgery yields significantly improved outcomes. The majority of patients exhibit improvement in ophthalmoplegia, visual field defects, and acuity immediately after surgical treatment with changes lasting for several weeks . Nonetheless, visual recovery in individuals with monocular or complete blindness is not expected to occur although some patients who became blind due to the condition have shown improvement if the surgery is performed very early after the onset of symptoms .
There are several factors that can predispose to the disease. They include treatment with bromocriptine, trauma to the head, irradiation of the pituitary, pregnancy, and stimulation tests. Hormonal influences may also play an important role with potential association with an intake of gonadotropin-releasing hormone and corticotropin-releasing hormone in the context of Cushing's syndrome. It is thought that patients with excess hormonal production, such as in acromegaly or Cushing's syndrome, are more vulnerable than others because of the increased response of the gland although others believe that apoplexy occurs in individuals with a silent gland. On the other hand, reports indicate cases of pituitary apoplexy after chemotherapy for acute myeloid leukemia treatment, cardiac bypass surgery, and ascending gradually to high altitude  .
Pregnancy is a major risk factor for pituitary apoplexy. It can either be associated with a pituitary adenoma that subsequently compromises the blood supply or with compromise of the arterial blood supply to the anterior pituitary. The latter condition is also known as Sheehan's syndrome in which hypertrophy of the gland in combination with the release of neurochemical factors increases the likelihood of arteriolar spasm and infarction. Sheehan's syndrome is accompanied by a deficiency of prolactin and gonadotropin, manifesting with an absence of lactation and amenorrhea.
Sheehan syndrome is a medical emergency and is characterized by very distinctive signs on MRI. Normally, the pituitary reaches its largest size in the postpartum period and can measure up to 11.8 mm while taking on a convex appearance. It then rapidly shrinks after the first week postpartum. T1-weighted imaging shows a hyperintense gland in pregnancy and in the immediate postpartum period. In Sheehan's syndrome, MRI reveals a "pituitary ring sign", in which the gland bulges from beneath the optic chiasma with a peripheral ring of enhanced signal and an isointense core .
Studies indicate that pituitary apoplexy occurs in approximately 1.5-27.7% of pituitary adenoma cases, although the actual incidence may be around 10%. Other reports show that only 0.6% of patients who had undergone surgery for pituitary adenoma developed clinically symptomatic pituitary apoplexy. 9.5% of all surgical samples showed evidence of bleeding and necrosis . However, when MRI is distinctly used for detection of hemorrhage within the pituitary tumor, the rate increases to about 26%.
Pituitary apoplexy results most commonly from excessive growth of a pituitary adenoma. Infarction and bleeding can also be responsible for the development of the condition. The nature of the vascular supply is likely to play an important role by increasing the vulnerability of the gland to infarction. The anterior pituitary is supplied by portal veins which eventually descend into the stalk of the gland, where they can be easily compressed.
Two major theories have been proposed to explain the development of pituitary apoplexy. The first theory postulates that the growth of the tumor physically impedes blood supply to the gland, resulting in infarction. A second theory suggests that rapid growth of the gland leads to a drastic increase in demand that the vascular supply is not able to support. This would also result in infarction and necrosis. The second theory is not well supported because apoplexy tends to also occur in slow growing tumors.
There are no known preventive measures.
Pituitary apoplexy refers to necrotic changes that occur within the pituitary gland. It was described initially by Pearce Bailey in 1898 and clinically defined in 1950 by Brougham et al.  . It most commonly occurs in close association with pituitary adenoma although it may also be associated with pituitary hemorrhage and infarction. There are two main theories proposed to explain the pathophysiological mechanisms leading to the disease. The first postulates that a gradually growing tumor compresses the hypophyseal stalk and impedes the normal blood supply to the gland, leading to ischemia and subsequent necrosis. The pituitary is thought to be particularly vulnerable to ischemic changes because of the unusual anatomy of its blood supply. The second theory proposes that a rapidly growing tumor strains the existing vascular system, with demand exceeding supply, leading to ischemic changes, infarction, and necrosis.
Patients with pituitary apoplexy most commonly present with a severe, sudden retro-orbital headache, although many cases are completely asymptomatic. Headache can also be generalized occur but is not necessarily associated with subarachnoid hemorrhage. Other prominent symptoms include deterioration of visual acuity, visual field defects, and altered mental status. The latter can range from mild lethargy to coma and is particularly ominous. It can signal rapid deterioration and necessitates surgical intervention. Diagnosis is established with MRI, although MRI changes indicative of hemorrhage and necrosis can be present in the absence of any symptoms .
Treatment of pituitary apoplexy depends on the severity of the symptoms although the most important initial action is directed at stabilizing the circulatory system. The deficiency in cortisol associated with the disease can lead to significant drops in blood pressure. Surgical treatment is recommended if visual changes are severe and worsening or in the context of significant altered mental status. Surgery is performed through the transsphenoidal route, enabling full access to the pituitary gland and permitting the decompression of critical structures. Patients with mild symptoms can be treated conservatively but need to be consistently followed up for any deterioration. Worsening of symptoms or a non-spontaneous response to medical treatment may require surgical intervention.
Prognosis is favorable if visual loss is not complete and if surgical treatment is performed very early after diagnosis.
Pituitary apoplexy refers to changes that occur in the pituitary gland leading to the death of its cells (necrosis). It most commonly occurs after the blood supply to the gland is compromised due to the presence of a pituitary tumor. The condition commonly presents with a severe and sudden headache that the patient localizes behind the eyes. It can also be completely asymptomatic. Other prominent symptoms include changes in vision, manifested by decreased acuity (strength of distinguishing objects in the visual field), double vision and blindness in particular areas of the visual fields (visual field defects). Patients can also suffer from lethargy, confusion, and coma if the disease is exceedingly severe. Treatment is directed at removing the tumor and relieving compressed critical structures, although medical intervention can be sufficient in mild cases. Patients can expect significant recovery if the surgery is performed early and if visual loss is not complete.