Skull Base Surgical Treatment Options
Skull base lesions present unique challenges given the complex anatomy of the region, their deeper location and their proximity to critical structures, including nerves, arteries, brain, and bone structures. The Skull Base Center is committed to seeking the best outcome for each patient with maximal preservation of function and quality of life, while using the least invasive treatment modality.
Treatment recommendations are made after careful analysis of radiological data; location and type of lesion; and evaluation of each patient’s unique health profile, needs and expectation. The treatment may include one or more of the following modalities: surgery, stereotactic radiation therapy (Gamma Knife®, CyberKnife®), interventional neuroradiology.
Radiosurgery is a technique that uses beams of radiation carefully directed at the tumor site from many different angles, providing a large dose of radiation directly onto the tumor with minimal exposure to the surrounding healthy tissue. Radiosurgery may be used as the primary treatment for skull base tumors or as an adjuvant treatment for residual tumor after surgery.
In some cases, tumors with high vascularity are embolized preoperatively, allowing safer surgical resection of the tumor and less blood loss.
Patients with cerebral aneurysms are evaluated by a neurosurgeon and an interventional neuroradiologist to determine the most effective treatment modality for each patient. Treatment for cerebral aneurysms includes intravascular packing and obliteration of the aneurysm with flexible coil or craniotomy and clipping of the aneurysm.
When surgery is necessary, preference is given to the use of minimally invasive techniques, including:
- Bi-directional approach
- Endoscopic-assisted microneurosurgery
- Focused skull base approaches
- Transfacial approach
- Transnasal Endoscopic approach
TRANS-FACIAL AND BIDIRECTIONAL APPROACHES
- Facial Degloving
- Head and Neck Approaches
Often the safest way to approach the skull base and minimize potential retraction of normal brain tissue is to access these lesions through the face. Whenever possible, we strive to avoid any facial incisions. Many of these tumors may be safely removed with endoscopic transnasal techniques. Occasionally, broader access is required and thus we often perform midfacial degloving (with small incisions placed within the nose and beneath the upper lip) to access the facial skeleton. Precise osteotomies are then made in the facial bones to allow them to be moved to the side and allow for wide, safe access to the base of the skull. The bone is reconstructed with plates and screws much as we do routinely in facial fracture management. If any bone requires removal, it is replaced with the patient’s own bone at the primary surgery if possible, to minimize any aesthetic downtime. Most patients are able to return to many of their routine activities within a couple of weeks of surgery.
For lesions that cross the anatomical borders between the intracranial and extracranial compartments, a bidirectional surgical approach using simultaneous access via focused craniotomy and transfacial or transnasal approaches allows access and control to both ends of the lesion, making surgical resection safer and more complete. In these cases, surgeons of different specialties work in a tandem and complementary fashion to provide multicompartmental access to the more complex lesion. Incisions are often made in the nasal and oral cavities to avoid facial scars and damage to the brain.
FOCUSED SKULL BASE APPROACHES and ENDOSCOPIC NEUROSURGERY
Focused skull base approaches and endoscopic-assisted microneurosurgery are used for intracranial skull base processes. These techniques allow resection of complex brain tumors such as meningiomas and cranial nerve neurinoma, which often displace or encase important nerves and arteries of the skull base and the brainstem. The use of small incisions and small cranial openings, allow the least amount of bone structures and soft tissue in and around the skull base to be disturbed. At the same time, they allow navigation outside the meninges (extradural) and under the brain, providing the most direct route to deep lesions at a specific target in the skull base. The incorporation of these techniques in the treatment of complex skull base lesions has enhanced safety, decreased post-operative discomfort and improved outcomes for patients.
Periorbital approach: Extensive experience with surgery of skull base lesions has allowed the neurosurgical team to use eyebrow incision in selected patients to provide minimally invasive focal periorbital approaches to target complex lesions in the region of the optic nerve, middle fossa, and internal carotid artery, such as meningiomas, trigeminal neurinoma, chraniopharingioma, and orbital tumors.
Periauricular approach: Small incisions around the ear take advantage of approaches through the temporal bone to access lesions in the posterior fossa, middle fossa and tentorial incisura, such as petro-clival meningioma, tentorial meningioma, trigeminal neurinoma, acoustic neurinoma, epidermoid, chordoma and chondrosarcoma. These approaches allow extradural surgical navigation under the brain causing the least manipulation of the cerebellum or the temporal lobe and less trauma to the surrounding soft tissue.
Trans-frontal sinus approach: This technique allows skull base access to the anterior fossa invasion with minimal retraction to the frontal lobes. It avoids large frontal craniotomies for lesions in the anterior fossa, such as olfactory groove and planum sphenodalis meningioma and tumor of the sinus or nasal cavity. This technique causes the least trauma to the brain and the veins and arteries of the frontal lobe.
Trans-nasal endoscopic approach: This approach provides access to extracranial lesions in the skull base and to pituitary tumors through the nasal cavity using endoscopic techniques. It permits endoscopic navigation, visualization of the skull base and resection of extracranial lesions, such as clival chordomas or chondrosarcomas, pituitary tumors and repair of CSF leak, with minimal trauma to facial structures. There is no manipulation of the brain, and avoids the need for a craniotomy with this approach.
Endoscopic-assisted microneurosurgery: This technique is used in combination with focused skull base approaches to allow the surgeon to see around the corners of important neuro and vascular anatomical structures without having to move them or enlarge the surgical approach.