The UNC Skull Base Center continues to provide multidisciplinary care for complex pathologies found in both the anterior and lateral skull base regions. As such, the Skull Base Center provides a matrix network comprised of a variety of disciplines involved. This organizational structure allows the institution to leverage the considerable collective talents of the group for the benefit of individual patients throughout the region. The team remains strongly committed to the concept of offering patients a balanced and unbiased opinion with all avenues being explored. The scope and experience of this group is vast, thereby providing patients the opportunity for a truly comprehensive evaluation.
In order to coordinate efforts, members of the Skull Base Team meet routinely. These meetings focus on multiple aspects including the complicated workflow of patient care, literature updates, and improvements to the complex organizational process. A special emphasis of the UNC Skull Base Team is to implement new treatment modalities as well as updated management concepts and technologies to ensure contemporary patient care.
Background and Philosophy
Historically, the complex anatomical relationships of many important structures within the skull base have made surgical management particularly difficult. Recent advances in surgical approaches, cranial nerve monitoring, endoscopic visualization, intraoperative imaging and navigation, neuroendovascular techniques, as well as intraoperative and stereotactic radiation have allowed dramatic improvements in patient outcomes and quality of life. Many of these improvements have been directly attributable to close collaborations between a variety of medical disciplines including Neurosurgery, Otolaryngology-Head & Neck Surgery, Radiation Oncology, Neurointerventional Radiology, and rehabilitative disciplines. For example, surgical approaches developed by rhinologists and neurotologists have allowed neurosurgeons access to tumors and other lesions involving the skull base without the need for traumatic brain retraction, resection, or in some instances, skin incisions. Moreover, working together, surgeons and radiation therapists have been able to apply precise anatomic knowledge to the delivery of highly focused radiation in an effort to avoid collateral tissue damage.
Skull base lesions are uncommon and clinical trials for treating many of these lesions are lacking. Patients are frequently left to seek opinions from a variety of clinical specialists including medical and radiation oncologists as well as surgeons in an attempt to find a consensus regarding optimal therapy. However, opinions are frequently divergent and dictated by the practitioner’s area of expertise rather than by patient factors. This creates significant uncertainty among both patients as well as referring physicians during difficult times.
Both Neurosurgery and Otolaryngology-Head & Neck Surgery have added faculty members with special interests and training in this area. For several years, The Department of Radiation Oncology has been able to treat patients via the Cyberknife Radiosurgical System. This system has a number of distinct advantages over its competition in that it allows for precise frameless delivery of either single dose or fractionated dose radiation to tumors throughout the body including the skull base.
Dr. Oliver Adunka serves as Director of the UNC Skull Base Center. Others from the Department of Otolaryngology-Head and Neck Surgery who are directly involved include Drs. Craig Buchman, Charles Ebert, Trevor Hackman, Harold Pillsbury, Brent Senior, William Shockley, and Adam Zanation, as well as nurses B.J. Squires, RN and Kristen Jewell, RN.
Other UNC disciplines involved in the Skull base center include Drs. Matthew Ewend and Deanna Sasaki-Adams from the Department of Neurosurgery, Dr. Julie Sharpless from Endocrinology, Dr. Jonathan Dutton from the Department of Ophthalmology, Drs. Mauricio Castillo, Benjamin Huang, Valerie Jewells, Keith Smit, and Sten Solander from the Department of Radiology, Dr. Robert Greenwood from Neurology, and Drs. Neil Hayes and Jing Wu from Medical Oncology. Sharon Cush, RN and Pasha Lemnah, RN help coordinate patient care and Diane Meyer, PT serves as the center’s primary physical therapist.
Lateral Skull Base
UNC has emerged a leader in the comprehensive management of acoustic neuromas (vestibular schwannomas) other intracranial neoplasms of the middle and posterior cranial fossae. While most tumors in this area are benign, they can pose a variety of clinical challenges and a highly individualized management scheme is typically required. Over the past decade, UNC has been able to build a substantial caseload with more than 75 evaluations per year. The Skull Base Team has continued to collect and evaluate patient outcomes using all three main surgical access routes. Overall, hearing preservation rates have remained around 75% in patients undergoing tumor removal via the middle fossa approach. Also, UNC offers the CyberKnife as an option for stereotactic radiation for small and medium size tumors.
A main emphasis of the UNC Skull Base Center is to offer hearing restoration via both cochlear and brainstem implantation in selected patients. Specifically, we have developed an FDA approved clinical protocol that will allow us to pursue auditory brainstem implantation (ABI) in children with cochlear nerve deficiency (CND) as part of a clinical trial. Typically, the ABI is a device that allows auditory stimulation in patients with Neurofibromatosis Type II (NFII), where both cochlear nerves are dysfunctional due to bilateral vestibular schwannomas. As such, the current efforts focus to potentially expand the indication criteria for this device beyond this group.
Vestibular schwannomas (Acoustic tumors) are by far the most common lesion in the cerebellopontine angle. A multidisciplinary approach ensures proper management, which can include watchful waiting, stereotactic radiation, or surgical excision via various approaches.
For patients with Neurofibromatosis Type II, we have begun to offer adjuvant systemic treatments. Specifically, Avastin® (Bevacizumab), an angiogenesis inhibitor, has been used in the management of several patients with NFII to facilitate tumor control and hearing outcomes. Preliminary results are certainly encouraging and correlate with previous data from the literature.
Other pathologies of the lateral skull base include temporal bone paragangliomas, and specifically jugular foramen tumors (glomus jugulare tumors). These tumors are slow growing vascular neoplasms mainly causing pulsatile tinnitus (pulsations that can be perceived in the affected ear) and hearing loss. Also, these tumors carry the potential to harm lower cranial nerves. In fact, their intimate involvement with certain nerves responsible for swallowing and voice production makes them difficult surgical cases. Radiation, on the other hand, often does not treat the patient’s symptoms of hearing loss and pulsatile tinnitus. Also, radiation treatment alone can damage the inner ear irreversibly and can thus affect the patient’s hearing and balance functionality. A new approach, which has been propagated by clinicians at Case Western University, has been to manage jugular foramen tumors via a planned subtotal resection and subsequent stereotactic radiation (CyberKnife). This treatment algorithm has been shown to resolve the patient’s symptoms while moving the radiation field away from the inner ear. Therefore, the patient typically undergoes a relatively small outpatient procedure followed by outpatient stereotactic radiation treatment that will most likely not compromise inner ear function.
MRI of a glomus jugulare paraganglioma originating from the jugular foramen and extending into the middle ear. A multi-modal management approach using planned subtotal resection of the middle ear content with subsequent sterotactic radiation has been chosen.
These latter examples demonstrate our dedication to a true multidisciplinary approach to managing skull base disease. In fact, members of the UNC Skull Base Team are proud to provide this type of clinical algorithm, which clearly benefits patient outcomes. It appears that most other centers use either a “surgery-centric” or “radiosurgery-centric” model depending on the institution’s expertise and interest. However, this institutional bias might not serve the patients’ best interests. At UNC, we are fortunate to have a unique skull base program that combines professional experience and skills, cutting edge technologies and facilities, and a burning desire to provide a balanced and unbiased opinion of the treatment options that serves the patient’s best interests. Cooperation through mutual respect for one another’s skills and opinions forms the backbone for this eclectic treatment philosophy.
Anterior Skull Base
Over the last 15 years,UNC has developed into a world leader in expanded endonasal skull base surgery generally and minimally invasive pituitary surgery (MIPS) specifically, with over 130 of these surgeries performed in the last year. Past UNC research has shown that MIPS results in shorter hospital stays, more rapid recovery and less overall complications compared to traditional open approaches. More recent work in a study of 50 patients undergoing MIPS at an average of two years follow-up showed no significant detrimental impact of the surgery on a patient’s sinonasal quality of life. Additional recent UNC research has shown a similar benefit with regards to the economics of this surgery, with a marked reduction in total healthcare costs related to MIPS compared to traditional techniques. With decreased length of stay and lower nursing costs, savings were found to average nearly 24%, over $3,000 less for each procedure.
Pre and 2 year post operative MRIs on a JNA with extensive skull base involvement with a complete resection via a single stage endoscopic endonasal approach (Drs. Zanation and Rose)
In the field of expanded endonasal skull base surgery. tumors such as meningiomas, craniopharyngiomas and sinonasal/skull base cancers have all been successfully managed with an endoscopic minimally invasive approach. UNC’s Skull Base Center is one of only a few in the country that offers expertise in both endoscopic and traditional transfacial or transcranial skull base surgery. This ability to offer all surgical options at the highest level allows for the best-individualized care. With this in mind, surgeons in the UNC Skull Base Center, have been among the first in the world to perform an endoscopic endonasal clipping of a cerebral aneurysm.
UNC surgeons have developed novel techniques of reconstruction of the skull base, including the development of the endoscopic pericranial flap for skull base cancer reconstruction. Additionally, UNC has the world’s largest prospective series of nasoseptal flap skull base reconstructions (over 300). Also, UNC has the largest known prospective cohort of vascularized endoscopic skull base reconstructions. The primary goal of endoscopic skull base reconstruction is to prevent post-operative CSF leaks. With adequate reconstructive measures in place, the overall post-operative CSF leak rate is 2.3% with an overall meningitis rate of 0.33%. Both of these results are significantly better than outcomes associated with traditional transcranial skull base reconstructions.
Also, it was noted that there is likely a long-term learning curve associated with endoscopic skull base reconstructions. If one compares the first 25 nasoseptal flaps ever published upon and the first 150 patients and the most recent 150 patients from our institution, there is a significant improvement in outcomes with more experience. As such, outcomes for the last 150 patients show a CSF leak rate of only 0.67%.
Other UNC Disciplines Involved
- Neurosurgery: Drs. Matthew Ewend, Deanna Sasaki-Adams & Pablo Recinos
- Radiation Oncology: Dr. Ronald Chen & Dr. Timothy Zagar
- Endocrinology: Dr. Julie Sharpless
- Ophthalmology: Drs. Syndee Givre and Jonathan Dutton
- Neuroradiology: Drs. Mauricio Castillo, Valerie Jewells, Keith Smith, Sten Solander, and Benjamin Huang
- Neurology: Dr. Jerry Greenwood
- Medical Oncology: Dr. Neil Hayes
- Nursing: Sharon Cush, RN, and Pasha Lemnah, RN
- Rehabilitation: Diane Meyer, PT