Newswise — DENVER (April 11, 2011) − According to the Central Brain Tumor Registry of the United States, 12.7 percent of all brain and CNS tumors diagnosed in 2010 were located in the pituitary. The vast majority of these are asymptomatic. While pituitary tumors are estimated to occur in 1 in 5 persons in the general population, clinically symptomatic adenomas are thought to occur in 1 in every 1000 persons. Tumors of the pituitary gland, often referred to as “the master gland” can cause striking physical, mental and psychological debilitation in patients. Pituitary tumors can result in Cushing’s disease, acromegaly, infertility and loss of vision. Many patients harbor a symptomatic tumor for years before a correct diagnosis is made.
Current primary management for most pituitary tumors (except for prolactin secreting tumors, which are treated medically) consists of surgery to completely remove the tumor and leave enough normal gland to correct hormonal function. An endoscope is used to access the pituitary through the nose and through endoscopic visualization, the tumor is safely removed. Despite advances in equipment, and transitioning from older microscopic surgery to newer endoscopic techniques, surgical removal of pituitary tumors can present an intra-operative challenge because it is difficult to visually differentiate tumor from normal brain and assess extent of resection. This results in a recurrence rate of approximately 10 percent over 10 years.
Researchers at Brigham and Women’s Hospital in Boston analyzed the value of fluorescence endoscopy in visually differentiating pituitary tumors from surrounding areas and its potential for improved tumor resection. The results of this study, Indocyanine Green Fluorescence Endoscopy for Visual Differentiation of Pituitary Tumor from Surrounding Structures, will be presented by Zachary N. Litvack, MD, MS, 3:10-3:24 pm, Monday, April 11, during the 79th Annual Scientific Meeting of the American Association of Neurological Surgeons in Denver. Co-authors are Suzanne A. Tharin, MD, PhD, and Edward R. Laws Jr., MD, FACS. Dr. Litvack will be presented with the National Brain Tumor Foundation Mahaley Award for this research.
This research utilizes a new and innovative type of endoscope developed by Dr. Laws, a neurosurgeon who pioneered the transsphenoidal (endonasal) operation for pituitary tumors and has performed more than 5,300 of these procedures to date. The researchers adapted a technique used in other surgical fields − the fluorescent dye indocyanine green (ICG) to visualize the microscopic vessels underneath the surface of the pituitary gland, the tumors, and the tissues surrounding the pituitary. They hypothesized that the fluorescent dye would cause tissues with many blood vessels to appear brighter than those that had a lower number of vessels. This would also enable visualization of larger vessels, including the carotid arteries, which are often at risk of injury during this type of operation.
Each patient underwent endoscopic videoangiography of the sellar dura and of the exposed pituitary adenoma after ICG bolus injection (12.5-25mg), with the customized 5mm zero degree endoscope using a near-infrared light source and excitation wavelength filter.
Key patient demographics
•16 patients screened for inclusion (9 males, 7 females)•12 patients completed study, 9 successfully•Median age 51.4 years (range 28-65 years)•Pathology: 2 Rathke’s cysts, 5 null cell pituitary macroadenomas, 1 ACTH secreting pituitary tumor (Cushing’s disease), 3 GH secreting pituitary tumors (acromegaly), 1 Prolactin secreting pituitary tumor (prolactinoma)
The ICG fluorescence from sellar dura, pituitary, and surrounding structures was successfully recorded in nine patients. It was determined that a standard dose of 25 mg in 10 ml of aqueous solution allowed good visualization of the sellar structures within 45 seconds of peripheral bolus injection. Adenoma was less fluorescent than normal pituitary gland. Dural invasion by tumor was identifiable by a marked increased in fluorescence compared to native dura.
“Since the initial trial proved successful and safe, 40 additional patients have been enrolled to date. The early results have been very promising. As predicted, we were able to visualize differences between tumor and normal pituitary tissues based on their vascularity. The dye also allowed us to clearly visualize the carotid arteries − which often lie immediately next to one or both sides of a tumor. Unexpectedly, we were also able to see areas where the tumor had invaded the dura, the lining around the brain and pituitary gland. Right now, this is the only institution performing fluorescent-guided endoscopic pituitary surgery, but we are hopeful that once this technique is proven safe with larger patient outcome data, that others will adopt this technique, said Dr. Litvack.
Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 8,000 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system, including the spinal column, spinal cord, brain and peripheral nerves.
Disclosure: the author reports no conflicts of interest. Karl Storz Endoscopy-America, Inc. provided custom built endoscopes and fluorescent light sources at no cost to support this research. The Karl Storz company has no control over the study design, data, or publication of these results.
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Media Representatives: If you would like to cover the meeting or interview a neurosurgeon − either on-site or via telephone − please contact the AANS Communications Department at (847) 378-0517 or call the Annual Meeting Press Room beginning Monday, April 11 at (303) 228-8431.
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