This 57-year-old female presents with hippocampal atrophy, sudden cognitive decline, and visual disturbances.
Q1 – Using images 1 and 2, what is the most likely diagnosis?
(a) Thrombosed aneurysm
(b) Pituitary apoplexy
A1 – (b) Pituitary apoplexy
Q2 – Which statement is false about pituitary apoplexy?
(a) Often requires urgent surgical decompression
(b) Often requires steroid therapy
(c) Occurs with microadenoma
(d) May be present with ophthalmoplegia
(e) May be associated with subarachnoid hemorrhage
Q3 – Which statement is false about prolactin-secreting adenomas?
(a) May be invasive with skull base destruction
(b) May be diagnosed with greater than 95 percent accuracy by prolactin greater than 200 ng/ml
(c) Mild elevations of prolactin (<100 ng/ml) can be related to medications, hypothyroidsm, or “stalk effect”
(d) Microadenomas may demonstrate the “hook effect” on laboratory studies
Pituitary apoplexy may often present as ophthalmoplegia, visual loss, and confusion in a patient with known pituitary macroadenoma.
Pituitary apoplexy is a surgical emergency requiring acute decompression. Steroid administration is required for endocrine support as the patient may exhibit acute pituitary insufficiency. Sometimes, intravenous T3 is also required.
Pituitary apoplexy may be associated with subarachnoid hemorrhage as well as vasospasm.
Prolactinomas are known to be invasive and, when large, can produce skull base erosion.
Prolactin is the only pituitary hormone which is regulated by an inhibitory mechanism. Large nonsecreting lesions which compress the pituitary stalk can result in elevations of the prolactin described as “stalk effect.” Elevations on this basis are relatively small as are those secondary to medications or hypothyroidism. A rule of thumb in elevating prolactin elevations is that the percentage of chance of a lesion being a secreting prolactinoma is about half of the level, so a prolactin of greater than 200 has an essentially 100 percent chance of being a prolactinoma.
Falsely low prolactin in the face or a large or invasive prolactinoma may represent the “hook effect” where the binding sites of the RIA antibody become saturated and the antibody curve is no longer proportional to the amount of prolactin. This is resolved by performing serial dilutions. This effect never occurs in microadenomas, but rather in macroadenomas.
A2 – (c) Occurs with microadenoma
A3 – (d) Microadenomas may demonstrate the “hook effect” on laboratory studies
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1. Diagnostic Imaging Brain Osborn et. al. Amirsys.
2. Greenberg MS Handbook of Neurosurgery. Thieme.
3. Liu JK, Couldwell WT Contemporary management of prolactinomas. Neurosurg. Focus 2004: 16 (4)