Axial and coronal MRI views showing trigeminal skull-base schwannoma involving the maxilla, orbit and infratemporal fossa, and extending intracranially.

Tackling Tumors in the Skull Base
By Sheila Noonan

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Danielle Weedo of Belleville, NJ, was diagnosed with a schwannoma of the skull base at age 20. Like her mother, sister and 11 other relatives, she has neurofibromatosis, an autosomal dominant genetic condition that causes tumors to develop along the body’s nerves. Although her tumor was benign, it had grown quite large. The tumor replaced much of her right maxilla, and extended to the posterior orbit, sphenoid sinus, infratemporal fossa and temporal lobe. She had a noticeable bulging of the right side of her face.

Among the 100,000 or so brain tumors diagnosed in the United States each year, about 5,000 fall into the category of skull-base tumors. Acoustic neuromas, meningiomas, pituitary adenomas, craniopharyngiomas and schwannomas are among the most common ones. While these tumors are generally benign and slow growing, they can become sizable, impinge on vital areas and sometimes cause significant problems, necessitating surgery.

The “geography” of the skull base, upon which the brain’s undersurface rests, consists of three main regions. Located above the eyes and the nose, the anterior region includes the olfactory bulbs, and cranial nerves that control movement of the eyeballs. The internal carotid artery and the cranial nerves involved with chewing and facial sensation, travel through the middle region; it is also where the cavernous sinus, an extremely difficult structure from which to remove tumors, is located. The posterior region is where the auditory canal and the lower cranial nerve are located; the jugular vein also passes through this region.

Every nerve carrying signals to and from the brain and every blood vessel carrying blood to and from the brain crosses the skull base. Until recently, tumors within this complex, bony region were difficult for surgeons to access safely, and the prognosis for patients was poor. But advances in technology and
microsurgical and endoscopic techniques have dramatically increased the capacity to safely remove many of these tumors.

Intraoperative capabilities, whether image-guided surgery or intraoperative MRI, offer valuable information to the surgeon in “real time” and can ensure that surgical goals are reached. “Being able to create three-dimensional, computer-generated images of the brain and map the patient’s brain and its ‘eloquent’ areas with functional MRI have revolutionized the way these surgeries are approached,” says Michael Schulder, MD, associate professor and vice chair of neurological surgery at New Jersey Medical School, and director of Image-Guided Neurosurgery at University Hospital.

In addition to new technology and techniques, the concept of a multidisciplinary surgical team to plan and perform these procedures has enhanced the success rate. “Skull-base surgery necessitates collaboration among otolaryngologists, neurosurgeons, ophthalmologists and plastic surgeons to remove the tumor, as well as preserve function and structural integrity,” says Soly Baredes, MD, chief of the division of otolaryngology-head and neck surgery at UH and associate professor of surgery at
NJMS. The team also includes interventional radiologists, radiation oncologists, oral and maxillofacial surgeons, pathologists and other specialists.

Breaking Down Barriers

The team approach eliminates some of the barriers that specialists working individually face when treating skull-base tumors. The composition of the team varies, depending upon the nature and location of the tumor.

“Tumors in the skull-base region certainly don’t respect a specialist’s turf,” says Baredes. “We encounter a broad gamut of lesions, such as squamous cell carcinomas, salivary gland tumors, or even large skin tumors that work their way deep into the nose, that are best handled by surgeons from multiple disciplines.” From an otolaryngologist’s perspective, tumors within the skull base can affect critical sensory and motor nerves, and impact the ability to breathe through the nose, speak or swallow. The preservation of nerves and vital blood vessels that traverse the skull base is crucial to ensuring a successful outcome.

Some members of the skull-base team at University Hospital; left to right: Ramzi O. Datiashvili, MD, Soly Baredes, MD, Michael Schulder, MD, and Roger Turbin, MD.

A high percentage of skull-base tumors also involve the eye. In fact, a change in vision is frequently the reason such patients seek treatment. The input of neuro-ophthalmologist and orbital surgeon Roger Turbin, MD, and Paul Langer, MD, who specializes in ophthalmic plastic surgery and orbital surgery, is pivotal. Both are assistant professors of ophthalmology at NJMS.

“Although we aren’t involved in every skull-base procedure, ophthalmology has an important role in the medical decision making that occurs in these cases,” points out Turbin. “There are many important visual components that travel through the skull base, controlling sensory vision and eye movement.”

“Skull-base patients often need some type of ocular reconstructive surgery, such as repair to the eyelids or the tear ducts, or reconstruction of the bones of the orbit,” adds Langer. “We try to do as much reconstructive work as we can at the time of the tumor removal, but sometimes further surgery is needed. Whenever possible, we perform these procedures with aesthetic considerations, placing incisions in non-obvious places.”

Another member of the skull-base team, Ramazi O. Datiashvili, MD, an assistant professor of surgery at NJMS, specializes in free-flap reconstruction, an intricate, microvascular technique that aids healing. “Once a tumor has been removed from the skull base, deep wounds remain that expose vital structures such as the brain, the sinuses, soft tissues, bones and muscles,” he explains. “To be protected, these structures need to be covered with well-vascularized tissues.”

During free-flap reconstruction, the plastic surgeon takes tissue from another part of the patient’s body, typically the back, abdomen, or forearm, and connects tiny vessels, providing blood supply to those tissues in the area left open by the tumor’s removal. Connecting tiny, often fragile blood vessels under a
microscope and working through tissue that in some cases is inflamed due to previous radiation therapy requires meticulous work. And while these surgeries are lifesaving in nature, Datiashvili, like other members of the team, is dually focused on the patient’s quality of life.

“My number one goal is to help the patient to have a satisfactory life, and part of that is covering the wound and protecting vital structures,” he says. “Another part is making surgical decisions that, to the best of my ability, preserve the patient’s appearance.” Axial and coronal MRI views showing trigeminal skull-base schwannoma involving the maxilla, orbit and infratemporal fossa, and extending intracranially. Some members of the skull-base surgery team at University Hospital; left to right: Ramazi O. Datiashvili, MD, Soly Baredes, MD, Michael Schulder, MD, Paul Langer, MD, and Roger Turbin, MD.

A New Concept

Just as the concept of a skull-base team has evolved over the past two decades, so has the physicians’
philosophy toward removing tumors and how such procedures affect a patient’s ability to function. Surgeons are less willing to sacrifice the patient’s speech and swallowing abilities, vision or other important functions for the goal of complete tumor removal. Other options, such as stereotactic
radiosurgery and chemotherapy, are used to pursue remnants of tumors that cannot be safely accessed.

The desire to preserve function in skull-base patients raises questions that weren’t necessarily asked 20 years ago. “Consider the patient who has a benign tumor in the cavernous sinus,” says Turbin. “Without surgery, there’s a chance that the tumor could cause double vision. With the surgery, double vision is almost certain. What’s the best choice? If I were the patient, I’d want the tumor to be watched and retain my normal vision for as long as possible.”

The Power of Teamwork

Danielle Weedo’s tumor was evaluated by several members of the skull-base team. They believed that the tumor could be removed. However, one of the major risks was facial paralysis. It was a risk she was willing to take.

From a preoperative MRI, the surgical group determined that arterial embolization, a non-invasive method of blocking arteries, would be needed to help control bleeding during the surgery. Jeffrey Farkas, MD, chief of Interventional Neuroradiology at UH and an assistant professor of radiology at NJMS, compares embolization to “shutting off the water before repairing a leaky pipe.”

“Embolization can be necessary for two main reasons,” Farkas explains. “These tumors can be very vascular, with numerous tiny, fragile vessels leading into them. Or there can be a major blood vessel leading to the brain that is surrounded by or feeding into the tumor. Even a small amount o blood, when
magnified 50 or 60 times, can be a big problem for a surgeon, and the last thing he needs is to stop the tumor resection to control bleeding.”

Not every skull-base surgery patient needs embolization. For those who do, Farkas wants to ensure that these patients can withstand having blood vessels blocked off. One of the worst case scenarios for a skull-base team is that the patient can’t withstand the blockage during the operation, throws a blood clot and has a stroke. So, under carefully monitored conditions prior to embolization, Farkas temporarily blocks blood flow with a balloon and gauges the patient’s physiological response.

The day after Weedo’s embolization, she underwent an 18-hour operation to remove the tumor. Schulder lifted Weedo’s brain to access the right side of her face, and Baredes used what’s known as a facial degloving approach—an incision under the lip and nose—to gain access to the tumor, combined with an infratemporal approach. “This technique helped preserve facial nerve function and did not require a facial incision,” says Baredes. The tumor had also invaded the orbit, destroying the entire bone underneath Weedo’s right eye. Langer removed this extension of the tumor, then reconstructed the entire floor of the right orbit to support the eye, preventing it from falling below the level of her other, normal eye.

The outcome was successful, with no facial paralysis, scarring or damage to her appearance. Weedo had lost some vision in her right eye due to the tumor, but the surgical procedure caused no further impairment.

Unfortunately, Weedo’s condition is not curable. She has been diagnosed with several additional tumors since removal of the first, and underwent surgery to remove a meningioma in September 2003. She will require removal of two acoustic neuromas in the near future. For now, these are being monitored as they are not affecting her hearing or balance. However, she is able to live a near-normal life—due to a winning team’s bold and expert initiatives.

THE SKULL-BASE SURGERY PROGRAM is an extension of the head and neck cancer program at UH, which is the largest such program in the state. Head and neck malignancies, including those found in the voice box, throat, mouth, salivary glands and sinuses, account for about 5 percent of all cancers nationwide, and 15 to 17 percent of all malignancies treated at UH.