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Nonfunctional Pituitary Adenoma

Nonfunctioning Pituitary Adenomas

  • Not every pituitary tumor (adenoma) causes hormone-related symptoms. When blood testing does not reveal an abnormally high hormone level, we call this a nonfunctioning pituitary adenoma. There are several possible reasons why nonfunctioning pituitary adenomas could arise, including:
    • The cellular production process of hormones typically involves making a much larger molecule, and then cutting it at the right places to make the hormone. In some cases, something is wrong with this cutting process and therefore a "functional" hormone is not made. It might be released into the bloodstream, but it is inactive and usually not detectable using standard blood tests.
    • In some cases, the hormone might be made inside the cell, but there is something wrong with the transport process that is required to release into the blood stream. When pathologists evaluate adenoma tissue acquired during surgery, they perform special stains to detect which hormones are present. For example, a nonfunctioning pituitary adenoma might stain strongly for prolactin, although the blood prolactin level is normal.
  • Nonfunctioning pituitary adenomas are a relatively common type of pituitary adenoma.
  • The vast majority of these tumors are benign, or not malignant. Most are large (macroadenoma), measuring more than 1 cm in size when finally diagnosed. Occasionally they grow quite large and invade the sinus cavity, causing nerve compression and double vision.
  • Some patients with large tumors may have acute bleeding into the tumor (pituitary apoplexy).

Symptoms

  • The most common symptom leading to diagnosis is progressive loss of peripheral vision (bitemporal hemianopsia).
  • Large tumors (macroadenomas) can cause partial or complete pituitary failure (hypopituitarism). The symptoms will depend upon which hormone is involved.
    • Reduction of sex hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
      • In men, this can lead to a low testerone level, causing decreased sexual drive and impotence. In some cases, there can be loss of body and facial hair
      • In women, this can lead to infertility
    • Large pituitary tumors can paradoxically elevate blood prolactin levels. This is thought to occur as a result of compression of the pituitary stalk (the connection between the brain and the pituitary gland). The chemical (produced by the brain) to control the pituitary production of prolactin actually inhibits prolactin release. When the pituitary gland doesn't get this signal, the normal pituitary gland produces more prolactin.
      • This is called the "stalk effect"
      • Prolactin levels are only slightly elevated, as opposed to prolactinomas in which the prolactin level is usually very high.
      • In men, slightly elevated prolactin levels usually result in no symptoms
      • In women, even slightly elevated prolactin levels can irregular menstrual periods
    • More severe hypopituitarism can lead to hypothyroidism or abnormally low cortisol levels. These can cause loss of appetite, weight loss or gain, fatigue, decreased energy, decreased mental function, dizziness and joint pain. 
  • Headache is common with pituitary tumors, especially larger tumor 

 

Diagnosis

  • Hormonal Testing
    • For patients with symptoms suggestive of pituitary failure (hypopituitarism), a complete evaluation of the endocrine system should be performed.
    • Based on results of these blood tests, additional hormonal studies may be ordered.
  • Visual Testing
    • For patients with visual complaints, an ophthalmologist should evaluate the patient.
    • This evaluation should include acuity testing of each eye and formal visual field testing to determine if there is loss of peripheral vision.
    • Visual field testing results from a patient with a bitemporal hemianopsia caused by a pituitary macroadenoma. Dark areas show areas of the visual field that have poor vision. One way to interpret these results is to imagine the patient is looking through a pair of binoculars. Everything lateral to the vertical midline is not visible on both sides (loss of peripheral vision).
  • Imaging

Treatment

  • Surgery
    • For the great majority of patients with symptomatic nonfunctional adenomas, surgical removal of the adenoma is the most effective treatment.
    • The long-term cure or control rate depends upon the extent of surgical removal, which in turn is related to:
      • the size of the tumor
      • tumor invasion into the cavernous sinus (the compartments on either side of the pituitary sella)
      • expansion of the tumor in the brain cavity
      • In cases in which it appears that all the tumor is removed with surgery, the cure rate is 70 percent to 80 percent.
    • UCLA surgeons are experts in minimally-invasive endoscopic techniques that maximize the changes of complete tumor removal.
    • MRI images taken before and after surgery from a patient with a nonfunctioning pituitary macroadenoma successfully treated using a minimally-invasive endoscopic approach. Note the optic chiasm is no longer compressed once the tumor is removed.
                                                                                 Video of the endoscopic removal of the case shown above
    • For larger tumors and especially those that invade the cavernous sinus, an expanded endoscopic endonasal approach may be the optimal surgical approach. UCLA neurosurgeons have an extensive experience with this technique.
    • Above, MRI images from a patient with an invasive nonfunctional pituitary macroadenoma. The tumor both invades the cavernous sinus and has protruded into the brain cavity. The image below taken during the endoscopic surgery, using the expanded endoscopic endonasal approach, shows the remaining tumor in the brain cavity, just above the optic nerve. The entire tumor was removed using this advance surgical technique.
    • Overall, surgery improves vision in 75 percent to 90 percent of patients, headache in 80 percent to 90 percent, and suppressed pituitary function in 10 percent to 30 percent.

 

  • Medical Therapy
    • There is no known effective medical therapy that reliably slows or stops growth of nonfunctional adenomas.
    • Hormone replacement may be necessary in patients with pituitary insufficiency.

 

  • Radiation Therapy 
    • Radiation is generally used as a second line therapy for endocrine-inactive tumors.
    • For patients with residual tumor or regrowth after the initial surgery, radiation or repeat transsphenoidal surgery or both are options.
    • Stereotactic radiosurgery is relatively effective in controlling growth  
    • Stereotactic radiosurgery may also cause loss of pituitary function in some patients.

The Neuro-ICU cares for patients with all types of neurosurgical and neurological injuries, including stroke, brain hemorrhage, trauma and tumors. We work in close cooperation with your surgeon or medical doctor with whom you have had initial contact. Together with the surgeon or medical doctor, the Neuro-ICU attending physician and team members direct your family member's care while in the ICU. The Neuro-ICU team consists of the bedside nurses, nurse practitioners, physicians in specialty training (Fellows) and attending physicians. UCLA Neuro ICU Family Guide

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