Otolaryngology
Head & Neck Surgery

Cranial Base Surgery

Cranial Base Surgery

Until recently, many deep seated tumors located in the vicinity of the brainstem or beneath the cerebral cortex were either entirely inoperable, of could be exposed only through injurious degrees of brain retraction. Historically, all approaches to tumors inside the head began by temporarily removing a window in the plate like skull surface. For tumors located deeply within this often meant pulling or pushing important parts of the brain out of the way. This could result in brain injury affecting movement, feeling, speech, mental abilities, and other adverse neurological consequences. The basic concept that underlies cranial base surgery is removal of bone, often in a clever and anatomically complex manner, to reduce or even eliminate the need for brain retraction. Skull base procedures, for example, may be designed to traverse the bone containing the ear (petrous bone), around the eye (orbit), through the nose or paranasal sinuses, low on the temple beneath the brain, or even upwardly directly from the neck region. Fundamentally, these are minimally invasive techniques to afford the highest possible degree of tumor removal while preserving neurological function to the greatest extent possible.

When were Cranial Base techniques developed?

Cranial Base Surgery is a relatively recent innovation. High resolution imaging, such as CT and MRI provides the surgeon with anatomical detail essential to the rational planning of these procedures. If you cannot precisely map the tumors location and surrounding relationships to brain, nerves, and bony landmarks, you cannot design a rational approach for its removal.

Technologies used in Cranial Base surgery

Microsurgery of these tumors is technologically intensive endeavor. High power microscopes with fiberoptic illumination are essential as are high powered drills (with diamond burrs) to safely navigate cranial base bone crisscrossed by vital structures. These procedures involve operating in a virtual forest of important nerves which crisscross the operative field.

Types of tumors approached with skull base techniques

A variety of different benign tumors such as meningioma, acoustic neuroma and other cranial nerve schwannoma, glomus jugularae, pituitary tumor, epidermoid, esthesioneuroblastoma, and many others are approaches with these methods. The anatomical regions covered include the roof of the nose and paranasal sinuses, cavernous sinus, Meckel's cave, clivus, petrous bone, cerebellopontine angle, jugular foramen, foramen magnum, and the upper cervical spine. Cancerous tumor, especially those that have eroded into the brain compartment from beneath, may also be approached using these methods. Skull base techniques are also sometimes employed to repair fractures of the skull base, for certain neurovascular disorders (e.g., aneurysms), as well as for certain deep seated infections of the skull base and the base of the brain.

Patient recovery following Skull Base surgery

Modern microsurgical skull base approaches have brought much improved results both in terms of tumor control, patient survival, as well as in numerous important quality-of-life measures.

Is surgery the only solution?

Not all skull base tumors require intervention. Some are so slow growing that they pose only minor risk of more serious problems, especially to older individuals. In such cases, the tumor may simply be monitored by periodic imaging studies. High technology radiation therapy is often an acceptable alternative and is at times preferable to microsurgery in selected cranial base tumors. The Cyberknife, which was developed at Stanford, is an extremely sophisticated tool for delivering focused radiation to skull base tumors while minimizing radiation exposure to sensitive surrounding structures. For more information: click here

Professionals involved in Patient Care

Management of tumors in and around the cranial base is a multidisciplinary endeavor involving neurosurgeons, neurotologists, head & neck surgeons, sinus surgeons, radiation oncologists, plastic surgeons, neuroradiologists, and neuropathologists, amongst others.

 

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