Surgery for Cushing's Disease

Target Pituitary

Cushings Syndrome:

The diagnosis of Cushing's syndrome is made on the basis of clinical assessment and dynamic hormone testing. The availability of new diagnostic and imaging techniques has improved the sensitivity of nricroadenoma detection. A positive MRI is useful, but MR images show no or equivocal evidence of tumor in 30% of pathologically proven cases.1 The false positive rate is up to 28%; therefore radiologic investigation must be used with hormone testing for tumor localization. Inferior petrosal sinus sampling clearly improves the certainty of diagnosis, and such data are useful in planning surgical therapy. In a small number of cases, however, tumor is found at operation on the side opposite to that predicted by the catheterization; it is important, therefore that both sides of the gland be explored. Nonetheless, we believe that an adequate diagnostic evaluation requires high field strength MRI as well as inferior petrosal sinus sampling in all cases of suspected microadenomas.

Neuroendocrine Center Bulletin Archives

Surgery for Cushing's Disease

Pituitary Home

Brooke Swearingen
by Brooke Swearingen, M.D.

Transsphenoidal microsurgery for Cushing's disease remains the single best therapy when compared with drug or radiation treatment. The current treatment algorithm has been recently reviewed. Surgical therapy at large centers offers an initial remission rate for micro-adenomas of 85-90%, with an overall complication rate of 3%, (including hormone deficiencies). Our own data over the past five years show a remission rate of 89% for first time surgery in microadenomas. If no tumor is found on bilateral gland exploration, we perform a hemihypophysectomy on the side predicted by the inferior petrosal sinus catheterization, which correctly localizes tumor side in about 70% of cases. In those patients who fail the initial procedure, repeat surgery for total hypophysectomy has been shown to be of benefit, with remission rates of 50%. If this is unsuccessful, treatment options include radiation and a variety of medical therapies. Even if surgical therapy is successful, patients require careful monitoring, since relapse rates of 10-20% at five years are reported.

Pharmacologic and radiation therapy remain options in those patients who are not cured or are unable to undergo surgical therapy. Ketoconazole, metyrapone, mifepristone and pasireotide are effective in achieving short-term chemical control. Stereotactic radiosurgery at the MGH Proton Center has been effective, with a remission rate of 50% at two years; therefore, interim medical therapy is required. Pituitary hormone insufficiency remains a problem after radiation (15-50%), and there is a small risk of optic nerve or cavernous sinus injury. Careful monitoring is again essential, since the maximal benefit of radiation may require years to achieve, and delayed loss of hormone function may occur.

Updated 1/14/15 BS and KKM