Transsphenoidal Tumor Resection
What is it?
Most pituitary tumors can be removed by transsphenoidal tumor surgery. This means the surgeon goes through the nose to get to the tumor. If you took a pencil and shoved it up your nose (don’t do this), it would point to the sphenoid sinus, an air passage at the back of the nose. By making a small hole in the bone here, the surgeon can see the bottom of the pituitary gland and the tumor.
What is the goal?
The goal of surgery is to remove as much of the tumor as is safe, and for most tumors the entire tumor can be removed safely.
How is it done?
After the patient is asleep, the surgeon will use fluoroscopy (a type of x-ray guidance) to insert a tube up one of the nostrils. Through this tube, the surgeon can use a powerful operating microscope to see to the back of the nose, and then the surgeon makes a hole in the bone at the back of the nose to see to the bottom of the pituitary gland. Using the operating microscope, the surgeon can see the difference between the normal pituitary gland and the tumor, and once the tumor is seen it can be removed.
Most pituitary tumors (especially large ones) are very soft and can either be removed in many small pieces or can be sucked out. Very small tumors can be hard to see, and this is where the experience of the surgeon can be critical in knowing how to look around in the normal pituitary gland for a small tumor without causing permanent damage to the normal gland.
In addition, very large tumors present special challenges, because much of the tumor cannot be easily seen through such a small hole. Sometimes image guidance is used to help the surgeon during tumor removal. Image guided surgery is a special type of stereotactic, or 3-dimensional neurosurgery. As part of the preparation for the surgery, patients receive a special MRI or CT scan within 3-days of their surgery date, sometimes on the same day as surgery. This scan is used in conjunction with a special 3-dimensional neuronavigation computer system. The system allows the surgeon to watch on a computer screen while performing surgery to determine if the instruments are on target, near critical structures of the brain that need to be preserved, and to know when all of the tumor has been removed.
Endoscopic surgery is also an important part of taking out large tumors through a small hole. An endoscope is a fiber-optic instrument that allows the surgeon to see around corners with very bright light; it allows the surgeon to see where additional tumor may be hiding behind critical arteries or nerves at the base of the brain near the tumor. This way, tumor that would normally evade detection can be seen and removed safely.
These new techniques, which are routinely used at the University of Rochester Medical Center, allow for safe, complete removal of even large tumors with less pain, no disfiguration (like bruising of the face or incisions where people can see), and all of this allows for better, quicker recovery.
What is the success rate?
The success rate for obtaining a complete tumor resection depends on the type of tumor being treated and its location. While complete tumor removal is usually desirable, if the tumor is too extensive or is too close to important nerves or blood vessels, it is more important not to injure normal brain tissue than it is to excise the tumor from excessively risky territory. We like our patients more than we hate their tumors.
What are the risks?
In the vast majority of cases, transsphenoidal tumor surgery is safe and effective. At the University of Rochester Medical Center we have had no operative deaths for elective transsphenoidal tumor surgery which is in line with the best university pituitary tumor centers in the country.
The most common risk is damage to the normal pituitary gland. For larger tumors (more than 1 cm in size) this happens between 5-10% of the time when the operation is performed by an expert pituitary surgeon. As a consequence, the patient may need to take new hormone replacement pills after the surgery, possibly including thyroid hormone, cortisol, growth hormone, estrogen or testosterone. Damage to the posterior, or back portion, of the pituitary gland may produce a condition known as diabetes insipidus, which will lead to frequent urination and excessive thirst, because the kidneys will no longer adequately retain water from the urine. This can be controlled with a nasal spray or pill form of a medication called DDAVP. Permanent diabetes insipidus occurs 1-2% of the time after pituitary surgery.
There is a very small chance of damaging the carotid arteries which are located on either side of the pituitary. This is a potentially devastating problem which could lead to stroke or death. It occurs very infrequently (less than once per 1000 patients undergoing surgery), when the operation is performed by an expert pituitary surgeon. Sometimes after surgery, there can be bleeding into the space where the tumor used to be, which could lead to pressure on the optic nerves or chiasm and possible blindness. This is also a very rare problem (less than once per 500 patients undergoing surgery), but might require another to remove the blood clot.
A cerebrospinal fluid leak through the nose sometimes occurs after surgery, because the only thing separating pituitary tumors from the spinal fluid (which surrounds the brain) is a very thin membrane. In order to prevent a fluid leak, the space where the tumor used to be is packed with a piece of fat taken from a tiny incision made in the abdominal skin. In spite of efforts to close off any leak, about 1 in 25 patients having surgery will still leak spinal fluid after surgery. If this happens, there is a risk of infection, called meningitis. If a spinal fluid leak occurs it can usually be treated without additional surgery, but it does mean a longer stay in the hospital until the leak is sealed, and in rare cases it may require a second operation to close the leak. The risk of all complications is higher with less experienced surgeons.
How long will I be in the hospital?
More than 60% of patients are able to go home the first day after surgery, and more than 90% of patients are able to go home by the second day after surgery. In rare cases, when the patient is already very debilitated because of the effects of their tumor, they may need to stay in the hospital for a third day, or may need to be sent to a rehabilitation hospital because of deconditioning after being sick for so long.
How long does it take to get the results of the tumor?
The surgeons and pathologists will take a quick look at the biopsy specimen at the time of surgery using a process known as a frozen section. This quick look allows the surgeon and pathologist to be sure that the biopsy specimen is abnormal, but is not sufficient to completely diagnose the problem. The final sections, which are chemically processed and stained portions of the specimen that are used to determine the final diagnosis, take 48-72 hours to process and examine.
What happens next?
This depends to some extent on what kind of tumor you have. For patients with acromegaly, prolactinomas, or Cushing’s disease, we will routinely perform blood tests while you are in the hospital to determine if surgery was successful at removing all of the tumor; these tests are important early indicators of surgical success, but the real answer about whether surgery was successful may take up to three months (after additional blood tests). For non-secreting pituitary pituitary adenomas, we will wait until three months after surgery to obtain a new MRI to see if the tumor was completely removed.For all patients after transsphenoidal pituitary tumor surgery, we assume that your normal pituitary gland will not be working properly for 1-2 weeks, and you will need steroid replacement. The dose of steroid you take will be tapered slowly, and we will follow along with you to make sure that you are taking the correct dose and that your normal pituitary gland is starting to function again. At three months after surgery, every patient will have blood tests to look at the full spectrum of pituitary function to determine if the pituitary gland is functioning normally, or if any hormones need to be replaced.