Radiosurgery for Cushing's disease after failed transsphenoidal surgery

Object. Although transsphenoidal surgery has become the standard of care fo r Cushing's disease, it is often unsuccessful in normalizing cortisol produ ction. In this study the authors investigate the safety and efficacy of gam ma knife radiosurgery (GKRS) for Gushing's disease after failed transspheno idal surgery. Methods. The records of all patients who underwent GKRS at the authors' ins titution after unsuccessful transsphenoidal surgery for Gushing's disease w ere retrospectively reviewed. Successful treatment was considered a normal or below-normal 24-hour urinary free cortisol (UFC) level. Records were als o evaluated for relapse, new-onset endocrine deficiencies, interval change in tumor size, and visual complications. Forty-three patients underwent 44 gamma knife procedures with follow up ran ging from 18 to 113 months (mean 39.1, median 44 months). Normal 24-hour UF C levels a were achieved in 27 patients (63%) at an average time from treat ment of 12.1 months (range 3-48 months). Three patients had a recurrence of Gushing's disease at 19, 37, and 38 months, respectively, after radiosurge ry. New endocrine deficiencies were noted in seven patients (16%). Follow-u p magnetic resonance images obtained in 33 patients revealed a decrease in tumor size in 24, no change in nine, and an increase in size in none of the patients. One patient developed a quadrantanopsia 14 months after radiosur gery despite having received a dose of only 0.7 Gy to the optic tract. Conclusions. Gamma knife radiosurgery appears to be safe and effective for the treatment of Gushing's disease refractory to pituitary surgery. Delayed recurrences and new hormone deficiencies may occur, indicating the necessi ty for regular long-term follow up.