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J Neurooncol (2014) 117:477484 DOI 10.1007/s11060-014-1386-5
CLINICAL STUDY
The pituitary stalk effect: is it a passing phenomenon?
Marvin Bergsneider Leili Mirsadraei William H. Yong
Noriko Salamon Michael Linetsky Marilene B. Wang
David L. McArthur Anthony P. Heaney
Received: 25 November 2013 / Accepted: 21 January 2014 / Published online: 19 February 2014 Springer Science+Business Media New York 2014
Abstract Most patients with large pituitary tumors do not exhibit hyperprolactinemia as a result of pituitary lactotroph disinhibition (stalk effect). Studies have demonstrated that increased intrasellar pressure is associated with both stalk effect hyperprolactinemia and pituitary insufciency. Our primary hypothesis was that, despite continued disinhibition, lactotroph failure is responsible for normoprolactinemia in patients with large macroadenomas. As a corollary, we proposed that the hyperprolactinemia phase, which presumably would precede the insufciency/ normoprolactinemic state, would more likely be discovered in premenopausal females and go unnoticed in males. Prospective, consecutive surgical series of 98 patients of clinically nonfunctional pituitary adenomas. Lactotroph insufciency was inferred by the coexistence of insufciency in another pituitary axis. The existence of pre-operative lactotroph disinhibition was inferred based on comparison of pre- versus post-operative prolactin levels. 87 % of patients with tumor size [20 mm and
normoprolactinemia had pituitary insufciency. Pre-operative prolactin in patients with pituitary insufciency were lower than those with intact pituitary function. Prolactin levels dropped in nearly all patients, including patients with normoprolactinemia pre-operatively. Premenopausal women had smaller tumors and higher pre-operative prolactin levels compared to males. No premenopausal female exhibited evidence of pituitary insufciency. Our study provides suggestive evidence that the stalk effect path-ophysiology is the norm rather than the exception, and that the nding of normoprolactinemia in a patient with a large macroadenoma is likely a consequence of lactotroph insufciency. In males, the hyperprolactinemia window is more likely to be missed clinically due to an absence of prolactin-related symptoms.
Keywords Hyperprolactinemia Pituitary adenoma
Dopamine Prolactin Pituitary insufciency
M. Bergsneider (&)
Department of Neurosurgery, David Geffen School of Medicine at UCLA, Gonda 3357, BOX 951761, Los Angeles,CA 90095-1761, USAe-mail: [email protected]
L. Mirsadraei W. H. Yong
Division of Neuropathology, Department of Pathology, David Geffen School of Medicine at UCLA, 18-161A NPI,BOX 951732, Los Angeles, CA 90095-1732, USA
N. Salamon M. Linetsky
Division of Diagnostic Neuroradiology, Department of Radiology, David Geffen School of...