Question from Steve:
I had my first surgery for a 3cm non-functioning adenoma(debulk only)in 2003 and a second surgery that was deemed a gross total resection this past june,2006-according to the operation report. The report also stated no evidence of cavernous sinus invasion.Well, I just had my 3mo. post op.MRI and was told by the surgeons assistant that there was a 5mm residual nodule in the left cavernous sinus. I understand these are inoperable due to bleeding and poor visualization in that area. I have also read about a proceedure called transcavernous craniotomy where it is possible to operate in the cavernous sinus but a 20% risk of cranial nerve damage sounds risky. However I’m afraid of delayed radiation effects such as hypopituitarism, optic nerve damage, and induction of secondary tumors(which I guess would be malignant) What are the rates of morbidity with gamma knife? Do you think the residual nodule could remain dormant?(the tumor stained negative for acth,prolactin and gh,if that matters).Thank you in advance-Steve
Dear Steve,
The rate of pituitary adenoma recurrence after resection is 20-50%. Cavernous sinus and dural invasion along with silent staining characteristics (silent ACTH or GH) correlate with a higher rate of recurrence.
Most neurosurgeons do not recommend intracavernous or transcavernous surgeries. They are associated with technical difficulty and high post-operative morbidity.
Gamma Knife surgery is the mainstay of treatment for recurrent or residual pituitary adenomas. Given the natural history of your adenoma and its demonstrated ability to recur and grow, I suspect the 5 mm residual nodule in the left cavernous sinus will grow over time.
At the University of Virginia, we have performed more Gamma Knife surgeries for patients with pituitary adneomas than anywhere else in the world. Our long-term results show a very favorable benefit to risk profile with Gamma Knife surgery for pituitary adenomas. Our local tumor control rate is 96%. The risk of delayed hypopituitarism is approximately 20-30%. Visual dysfunction has occurred in less than 1% of our pituitary adenoma patients. The exact incidence of Gamma Knife induced tumor formation or malignant transformation of an existing tumor is not known. However, the incidence is believed to be less than 1 in 1000. To date, we have never observed Gamma Knife induced neoplasia following treatment of a pituitary adenoma nor has there been a case reported in the literature.
Sincerely,
Jason Sheehan
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