The Danger of a Large Pituitary Tumor: Pituitary Apoplexy

The pituitary gland is a small gland about the size of a pea located in the skull, below the brain and above the nasal passages. A large pituitary tumor can press up and damage the brain and nerves. Most pituitary tumors are benign (noncancerous) and slow growing.

Pituitary apoplexy is a clinical syndrome due to abrupt hemorrhaging and/or infarction of the pituitary gland, generally within a pituitary tumor, also known as a pituitary adenoma. Pituitary adenomas are tumors of the anterior lobe of the pituitary gland. Pituitary apoplexy complicates 2%-12% of pituitary adenoma, especially nonfunctioning tumors.

Pituitary apoplexy usually occurs in patients with macroadenoma. A macroadenoma refers to a pituitary tumor that is larger than 10 millimeters; pituitary tumors smaller than 10 millimeters are known as microadenomas.

Pituitary adenomas are particularly prone to bleeding and necrosis, possibly because they outgrow their blood supply and they can grow and press upon nearby brain structures. The inherent fragility of tumor blood vessels may also explain the tendency to hemorrhage.

The Symptoms of Pituitary Apoplexy

Headache is present in more than 80% of patients with pituitary apoplexy and is generally the initial manifestation, with sudden and severe onset. Visual disorders are present at presentation in more than half of patients with pituitary apoplexy.

More than half of patients with pituitary apoplexy have ocular palsy, due to functional impairment of cranial nerves III (the most affected), IV and VI. This may be due to the intracavernous expansion of the tumor mass, to a hematoma, or most probably, to an abrupt pressure increase in the pituitary region.

How to Diagnose Pituitary Apoplexy

The best tools for diagnosing pituitary apoplexy are CT and MRI by revealing a pituitary tumor. CT confirms the diagnosis by revealing a pituitary tumor with hemorrhage and/or necrotic components. Even if no necrosis or hemorrhage is found, these imaging methods offer confident diagnostic confirmation.

Diagnosis relies on a combination of clinical manifestations (e.g., headaches and visual disturbances) and the presence of a pituitary adenoma, whether previously known or discovered during the workup. Imaging studies are thus crucial for diagnosis.

CT can help eliminate this diagnosis by showing an intrasellar mass, with hemorrhagic components in 80% of cases. CT is most useful in the acute setting (24-48 hours); after this time, blood intensity decreases and may be difficult to detect.

The Treatment for Pituitary Apoplexy

The treatment aims are to improve symptoms and relieve compression of local structures, particularly the optic pathways. Surgical decompression (removal of the pituitary tumor) is probably the most rapid means of achieving these goals. Empirical steroid supplementation should be offered to all patients with signs of pituitary apoplexy, without waiting for diagnostic confirmation.

Most neurosurgeons now prefer an endoscope to an operative microscope. The goal being optical pathway decompression, the surgeon must attempt to identify the sellar diaphragm. Gross subtotal removal is preferred if the adenoma is invasive.

In the acute setting, the operation sometimes has to be performed by an on-call neurosurgeon rather than a skilled pituitary neurosurgeon. Surgery carries a risk of cerebrospinal rhinorrhea, damage to the posterior pituitary (risk of permanent pituitary insipidus), and hypopituitarism due to removal of normal pituitary tissue.

If the surgical option is chosen, the transphenoidal approach is almost always recommended because it allows good decompression of the optic pathways and neuroanatomic structures in contact with the tumor and because it is associated with low postoperative morbidity and mortality.

The Prognosis After Surgery for Pituitary Apoplexy

After surgery, pituitary function recovers partially or completely in more than 50% of cases. Another major argument in favor of the surgical approach is that surgery can remove the pituitary tumor. However, many patients have no visible tumor remnant after an apoplectic episode managed conservatively.

If surgery is chosen, then timing is important. If the patient is operated on more than one week after onset, then the prognosis of any visual defects is less good. 86% of visual disorders improved or resolved when surgery took place within 8 days, versus 46% between 9 and 34 days.