New Pathways to Reach and Treat Brain Tumors
New techniques and collaborations are now enabling skilled neurosurgeons to reach and treat conditions that emerge in difficult to reach areas of the skull base.
The skull base is the foundation for the brain and all its important contents: The same five bones that form the bottom of the cranium also form the eye socket, roof of the nasal cavity, some of the sinuses and bone around the inner ear. It is a crowded area that houses important structures (the carotid artery and ear and balance structures) and is filled with nerves and blood vessels, along with needed openings for the spinal cord, blood vessels and important nerves to pass through.
“Skull base surgery” refers to state-of-the-art techniques to reach deep into the skull base with minimal or little injury to surrounding structures. Tumors that arise in the base of the skull include:
- non-cancerous and slow-growing vestibular schwannomas (also called acoustic neuromas);
- meningiomas, most of which are non-cancerous;
- chordomas, which grow slowly and are malignant but can be treated;
- chondrosarcomas, which are rare and very occasionally occur in the skull base.
Pituitary tumors, which are mostly noncancerous but can disrupt hormonal balance, are also accessed through skull base surgical approaches. Skull base surgery also is used to address some nerve problems, such as trigeminal neuralgia (chronic pain that affects the face) or defects of the base of the skull.
In the past, fully removing some of these tumors was regarded as impossible, said Ian F. Dunn, MD, a neurosurgeon and director of the Center for Skull Base and Pituitary Surgery at Brigham and Women’s Hospital. New collaboration among specialists is changing that, he notes. “Our expertise has allowed us, in most cases, to try for complete removals of these pathologies for cure or alleviation of symptoms.” He credits leadership from two of the field’s pioneering surgeons, Ossama Al-Mefty, MD and Edward R. Laws MD, both at BWH.
It Takes a Team to Reach Tumors in Difficult Locations
To address hard-to-reach tumors, collaborations among experts from many disciplines is the key. The BWH Skull Base Program draws upon specialists in neurosurgery; otolaryngology (or ENTs, for Ear, Nose, and Throat); plastic and reconstructive surgery; ophthalmology; and experts in neurophysiology and radiation oncology. Together, they offer comprehensive management of these complex tumors, which usually involves surgery but can also include radiation or forms of medical therapy.
With so many different experts contributing, said Dr. Dunn, “there's not one approach that we rely on for everything. We have at our disposal and in our skill set any approach that's required to reach any corner of the skull base.”
This includes conventional approaches that occasionally require removing a portion of skull base, said Dr. Dunn. “With what we call lateral skull base surgery, most commonly used for vestibular schwannomas, we take advantage of the skills of our neurotology colleagues who are also experts in how the temporal bone relates to the parts of the ear and balance apparatus,” says Dunn. Neurosurgeons and neurotologists together evaluate patients – before surgery, in the operating room and afterward.
An innovative approach to reach tumors at the skull base is through the nasal cavity (called endonasal or extended endonasal surgery). Small cameras, called endoscopes, with strong light sources enable doctors to see the area in order to reach tumors that historically may have been reached through larger incisions in the top of the forehead.
“When we do endonasal surgery, especially if we're doing something extensive, we really appreciate and benefit from deep expertise that our ENT colleagues have in accessing some of these corridors,” he added.
These less invasive techniques make it possible for surgeons to reach the tumor in a safe and faster surgery than previously, with fewer complications and faster recovery. Minimally invasive techniques maximize tumor removal while preserving neurological function to the greatest extent possible.
Bringing together traditionally separate disciplines – all to treat diseases at the skull base – and putting the experts all under one roof results in innovative approaches to some of these hard-to-treat conditions.
Early Signs and When to Seek Evaluation from a Physician
How would someone know if symptoms require evaluation for a tumor? Because tumors of the skull base are located near many nerves and blood vessels that are extremely close to each other, they first show symptoms in some ways you may not expect.
Vestibular schwannomas (acoustic neuromas) for example, may show their first signs through hearing loss or dizziness. Tumors a little bit farther forward can affect the visual system. Individuals may notice visual loss in one or both eyes, which is especially common with tumors in the pituitary gland that arise near the visual nerves. In these situations, patient first see a physician in their primary care practice or an emergency room.
Once referred to a specialist at BWH, a patient may see a number of specialists such as Dr. Dunn and colleagues from multiple disciplines all in one visit. This way, patients can accomplish in one appointment what used to take many separate visits, often in different locations, to diagnose the issue or plan a course of treatment.
Bringing the specialists together adds value to the care of these patients, said Dr. Dunn: “All of us really have the same goal, which is a transformational way of taking care of patients.”
Ian F. Dunn, MD, Director, Center for Skull Base and Pituitary Surgery at Brigham and Women’s Hospital describes novel surgical treatment for skull base and pituitary tumors.