Case study - A pituitary tumor recurs

By Daniel Rohrer, M.D.
Co-medical director, Providence Cranial Services
Providence St. Vincent Medical Center
Comprehensive Neurosurgical Consultants

Large recurrent nonsecretory pituitary tumors pose significant challenges for successful treatment. Medical treatment to reduce tumor size is nonexistent for endocrinological inactive tumors. Stereotactic radiosurgery is contraindicated for tumors presenting with marked optic chiasm compression. Repeat surgical removal is hindered by loss of normal tissue planes, scar tissue formation, tumor multicompartmentalization, and typical invasion into the cavernous sinus and other parasellar structures.

Regardless, by using minimally invasive endonasal endoscopic techniques, successful resection can be achieved with very low morbidity and significantly reduced hospital stays.

Case presentation
The patient is a 61-year-old diabetic male referred by another neurosurgeon for consideration of minimally invasive endoscopic skull base surgery. In 2005, the patient underwent a subtotal resection of a very large nonsecretory macroadenoma through the standard sublabial transsphenoidal approach. Following surgery, the patient’s bitemporal hemianopia improved significantly, despite incomplete resection.

In 2009, the patient developed recurrent visual field deficits and progressive headaches. Neuroendocrine studies showed only low testosterone and IGF-1 levels. Repeat MRI revealed a large recurrent tumor with marked compression of the optic chiasm, erosion of the clivus and invasion of the right cavernous sinus.

Figures 1,2

Surgical resection of a multicompartmentalized, fibrous adenoma was achieved through an expanded, fully endoscopic endonasal approach using image-guided surgical navigation. This included removal of tumor from the suprasellar region, clivus and right cavernous sinus. Normal gland was visible toward the left of the sella and remained intact.

Following surgery, the patient had marked improvement of vision, resolution of headaches and no additional endocrine abnormalities. He returned home two days later. Immediate postoperative MRI showed a radiographic total resection of recurrent tumor with the normal gland and infundibulum deviated left.

Figures 3, 4

Discussion
Based upon epidemiological cadaver studies, 15 percent to 20 percent of the general population harbors pituitary tumors, typically microadenomas. In neurosurgical literature, pituitary adenomas are relatively common lesions, comprising approximately 10 percent of intracranial tumors. These tumors are classified as hormonally active (secretory, functional) or hormonally inactive (nonsecretory, nonfunctional) adenomas.

The most common secretory tumor is a prolactinoma, which can cause amenorrhea-galactorrhea in females and impotence/infertility in males. Many of these tumors can be treated medically with dopamine agonist drugs. Growth-hormone-secreting tumors are the second most common. They can cause acromegaly in adults and gigantism in children. ACTH secreting tumors follow in frequency and produce Cushing’s disease (or Nelson’s syndrome in bilateral adrenalectomy patients).

Approximately 30 percent of pituitary adenomas are nonsecretory. They become symptomatic by causing compression on surrounding structures. Pituitary compression can result in hypopituitarism. Optic chiasm compression can result in visual field disturbance, typically bitemporal field cuts. Cavernous sinus invasion can result in extraocular muscle palsies. Headaches and CSF leakage can also occur. Pituitary apoplexy may be the initial presentation of 3 percent to 9 percent of macroadenomas (greater than 1 cm in diameter).

When medical therapy fails, or is suboptimal to nonexistent, microsurgical resection is considered via either transsphenoidal or craniotomy-based approaches. The exact surgical approach is based upon the patient’s presenting symptoms and general health, tumor morphometry and the surgeon’s experience.

Standard sublabial or transnasal transsphenoidal microsurgery is the most popular approach for most pituitary tumors. Stereotactic radiosurgery or radiotherapy may be considered in certain situations, especially for residual tumor in the cavernous sinus or in medically fragile patients. However, these latter modalities are limited by tumor proximity to the optic nerves, chiasm and tracts. With time, radiation-based treatment may also render the patient panhypopituitary.

Even in the best hands, long-term tumor control rates are 50 percent to 80 percent following microsurgical resection alone. Recurrent or progressive residual pituitary tumors pose additional treatment challenges. Often, recurrent tumors invade the cavernous sinuses and other supra- and parasellar structures. In addition, recurrent tumors may be scarred down, fibrous and multicompartmentalized. This would potentially lead to a higher incidence of surgical complications, including CSF leakage, neuroendocrine dysfunction, visual impairment, carotid artery injury, stroke and death.

Recent advances in minimally invasive endonasal endoscopic skull base surgery have revolutionized surgery for pituitary and parasellar tumors. Visualization is significantly improved with a direct endoscopic view, and patients recover much faster with less discomfort. Typical hospitalization has diminished to one or two days, even following complex surgery.

Other than for pituitary tumors, this approach can be used for Rathke’s cleft cysts, chordomas, chondrosarcomas, meningiomas, craniopharyngiomas, parasellar malignancies and repair of skull base CSF leaks. Although a steep learning curve is required to master these techniques, we have successfully performed a variety of pituitary and parasellar tumor resections in this fashion for more than five years.

Our latest and most exciting neurosurgical advancement is the acquisition of high-field, mobile intraoperative MRI imaging on the Providence St. Vincent Medical Center campus. This technology is seamlessly integrated with the most advanced surgical navigation system available and with our well-established endoscopic skull base capabilities.

We can now update our navigational devices during surgery, check for complete resection and rule out potential complications before leaving the operating room. This unsurpassed capability will maximize our care of patients with a variety of intracranial pathology, including those with pituitary and parasellar tumors.