Skull Base Surgery
Washington University otolaryngologists, neurosurgeons and other specialists collaborate on an endoscopic or endonasal approach to treat diseases of the skull base. These conditions include pituitary tumors, chordomas (spinal column tumors), chondrosarcomas (cartilage tumors), meningiomas (brain and spine tissue tumors), other brain tumors, cerebrospinal fluid (CSF) leaks, and certain types of cysts.
Advances in Skull Base Surgery
Traditionally, the surgical approach for many of these diseases was through a craniotomy, an opening of the scalp and removal of a piece of the skull or via facial incisions, to gain access to the specific disease process.
Now, through the use of endoscopic/endonasal procedures, a surgeon does not need to make incisions in the scalp and/or face. Instead, a surgical team advances an endoscope (a small camera at the end of a rigid tube) through the nasal cavity to view the anatomy, as well as other instruments that are necessary to perform the operation.
Because endoscopic/endonasal procedures are minimally invasive, they avoid many of the debilitating aspects of traditional surgery such as blood loss and longer recovery times, while accomplishing the same results as open (traditional) operations.
Skull base conditions treated with minimally invasive endoscopic technique
Intraoperative Magnetic Resonance Imaging (iMRI)
To make the surgery as safe and effective as possible, MRI and CT guidance is used throughout the procedure. In addition, High Field Strength intraoperative magnetic resonance imaging (iMRI) is also commonly employed. With an IMRI, surgeons can remove a tumor and stop the operation to acquire MRI images while the patient is still in the operating room asleep. The mobile IMRI machine slides out on a track and takes images. Surgeons then have the ability to remove any remaining tumor that is accessible.
The pituitary gland is a master gland that produces and secretes many hormones that travel throughout the body including growth hormone; prolactin; adrenocorticotropin (ACTH), which stimulates the production of cortisol (a hormone active in metabolism); and thyroid-stimulating hormone (TSH).
Pituitary tumors are among the most common brain tumors. They are almost always benign and cause symptoms either through compression of nearby cranial nerves or overproduction of hormones. Common compression symptoms include blind spots, blurred vision or sometimes double vision. Overproduction of hormones by the tumor leads to a variety of symptoms.
Pituitary tumors that are large and cause compressive symptoms require treatment with surgery often being the treatment of choice. Hormone-producing tumors are treated primarily through surgery with the exception of prolactin-producing tumors, which typically are treated with a drug called bromocriptine. Traditionally, pituitary tumors were removed through more invasive surgeries using an incision beneath the lip or at the front of the nose.
Craniopharyngiomas are benign tumors that arise from portions of the pituitary gland or stalk. These tumors typically are partially cystic and partially calcified and cause symptoms either by decreasing pituitary hormone production or compressing the optic nerves, leading to visual decline. Craniopharyngiomas commonly occur in children, but can grow and cause problems in adults. They tend to grow slowly (over months to years), but their location can make treatment difficult.
Generally, the treatment of choice for craniopharyngiomas is surgical removal. Surgery previously was done through an open craniotomy, requiring an incision of the scalp and removal of part of the skull. However, many craniopharyngiomas now may be removed through an endoscopic/endonasal approach.
Rathke's Cleft Cysts
Rathke's cleft cysts are cysts with a lining that produces fluid and causes the cyst to enlarge slowly over time. Like pituitary tumors, they can cause compression of the optic nerve, leading to decreased vision, or pressure on other cranial nerves, resulting in double vision.
Generally, surgical drainage or removal is the treatment of choice for Rathke's cleft cysts. In the past, Rathke’s cleft cysts were treated with a transsphenoidal approach that uses an incision below the lip or in the front of the nose. The endoscopic/endonasal approach allows for excellent treatment without the use of these incisions.
Chordomas and chondrosarcomas are rare, malignant tumors that typically arise in and around the clivus, a major bone of the skull base. Both tumors grow very slowly over a period of years and can be difficult to treat because of the location and extent of the tumors.
Generally, the treatment of choice for chordomas and chondrosarcomas is surgical removal of as much of the tumor as possible, followed by radiation therapy. In the past, tumor removal required facial incisions and displacement of the facial skeleton. Adoption of the endoscopic/endonasal approach has been a major step forward in the surgical treatment of these tumors and has resulted in improved patient outcomes.
Meningiomas are tumors that arise from the covering of the brain known as the dura or meninges. They typically are benign and may occur at the base of the skull. Previously, these tumors were removed through a craniotomy, or surgical removal of a portion of the skull. Some meningiomas now may be removed through an endoscopic/endonasal approach, avoiding the side effects of a craniotomy including a prolonged recovery time.
Cerebrospinal Fluid Leaks
Cerebrospinal fluid (CSF) surrounds the brain and serves as a preventive barrier. A person with a CSF leak is at risk for meningitis, a serious infection of the brain. CSF leaks can result from trauma or from other causes. CSF leaks can occur anywhere in the skull base. Traditionally, surgeons made a large opening in the skull to visualize the site of the leak after lifting up the brain. Many CSF leaks can now be repaired using an endoscopic/endonasal approach.
Other Skull Base Processes
In addition to the more common processes listed above, we also treat for more unusual pathologies such as melanomas, adenoid cystic carcinomas, esthesioneuroblastomas and juvenile nasopharyngeal angiofibromas with these same endoscopic techniques.