The skull base is one of the most complex regions of the human body. Vital blood vessels and major cranial nerves pass through the base of the skull, making it a delicate area demanding precise skills for successful surgical interventions. Many disorders, including brain tumors, pituitary tumors, congenital craniofacial deformities, microvascular nerve compression syndromes (trigeminal neuralgia and hemifacial spasm), cranial extensions of head and neck cancers, acoustic neuromas, meningiomas and chordomas, however, require surgical intervention in the skull base region. The dedicated neurosurgeons at the Department of Neurosurgery, using the latest imaging technology, have extensive experience in this area and are dedicated to treating these potentially devastating disorders.

• Meningiomas
• Cerebral Aneurysm
• Arteriovenous Malformations (AVM)
• Acoustic Neuroma
• Chordomas
• Cranial Extensions of Head and Neck Cancers

Meningiomas are tumors that originate from the meninges, which are membrane-like structures that surround the brain and spinal cord. Typically, they are benign and occur as solitary masses, but instances of malignancy and multiple concurrent lesions have been reported. About 15 to 20% of all primary brain tumors are meningiomas and commonly occur in the fourth through the sixth decade of life, mostly affecting women. Despite various theories, the origin and cause of the tumors is unknown.

Indications for surgical resection depend on clinical progress and the size and location of the tumor. In critical patients with worsening symptoms, resection of the mass is a priority. Advances in diagnostic tools, neuroanesthesia, surgical instrumentation and innovative surgical techniques have enabled surgeons to offer resection to a greater number of patients with less associated surgical risk.

The goal of surgery is complete tumor removal. The technique employed depends on the location of the tumor. When the tumor cannot be completely resected at the time of surgery, adjuvant radiotherapy or radiosurgery may play a role in subsequent management of the patient.

Tumors once thought to be "unresectable" are now regularly and safely removed at the Maxine Dunitz Neurosurgical Institute. Meningiomas located at the base of the skull are very difficult to access. Our use of highly specialized surgical techniques, sophisticated intraoperative monitoring equipment and minimally invasive surgical instruments allows us to expose hard-to-reach areas in their entirety without disturbing surrounding critical neurovascular structures.

Patient outcomes depend on the nature of the tumor and the therapeutic plan that is followed. It is difficult to summarize all treatment results, but the range of treatment options that are currently available provides a suitable approach to most every individual case.

A cerebral aneurysm is an abnormally dilated segment of a blood vessel surrounding the brain. In some cases, the entire blood vessel widens and expands to resemble a balloon-like structure.

Cerebral aneurysms occur in three to five percent of the general population, are more common in patients older than 30 and are almost twice as common in women than men. The exact cause of many cerebral aneurysms is not completely clear. In general, aneurysms are thought to arise from weakened areas in the wall of a blood vessel. Some aneurysms may occur as a congenital defect in the lining of the blood vessels, resulting in continued enlargement of the aneurysm over time. There appears to be a familial component to the development of aneurysms, as they are much more common in first-degree relatives, especially siblings. On rare occasions, multiple occurrences are reported in the same patient. Aneurysms frequently have a thin wall and are particularly prone to rupture or bleeding.

Several factors can induce weakening of the blood vessel wall, including infection, trauma, brain tumor and arteriovenous malformation (abnormal blood vessel development). Factors that have been shown to increase the risk of aneurysm rupture include smoking, excessive alcohol consumption and arteriosclerosis.

Once an aneurysm ruptures, blood accumulates between the brain and the subarachnoid space (a thin wall surrounding the brain), resulting in a subarachnoid hemorrhage (SAH). As blood collects in this space, it compresses and damages the surrounding brain tissue. The tissue injury causes the surrounding blood vessels to be susceptible to vasospasm (an abnormal constriction of the blood vessels of the brain, which can result in additional tissue damage through diminished blood flow to the brain). The combined effect of bleeding and vasospasm can result in serious neurologic impairment or even death.

Arteriovenous malformations (AVM) involve an abnormal connection between one of the brain's arteries and veins. Although most AVMs are congenital, the exact cause of their formation is unknown. Approximately 0.14% of the U.S. population is affected with AVMs, and the incidence is equal in men and women.

AVMs are troublesome for many reasons. First, AVMs allow blood from the heart to bypass the brain's capillaries, which normally deliver oxygen and nutrients to the brain tissues. This may result in neurologic deficits.

The detoured blood also causes increased pressure on the fragile wall of AVM. The AVM may become swollen due to the effects of this pressure. The ballooned AVM can press down on adjacent brain tissue, inducing seizures or causing compressive damage to surrounding brain tissue.

A much more serious complication is the risk of an AVM hemorrhage (bleeding). This can be a life-threatening emergency, damaging surrounding brain tissues and in severe cases may even result in death. It has frequently been observed that small AVMs tend to bleed more frequently than larger ones. Once an AVM has bled, the re-bleed rate is 4% per year. Fortunately, hemorrhage from an AVM is rarely fatal (<10%), which is in contrast to the high mortality rate of ruptured aneurysms (>90%). However, neurologic deficits can still result from the compression and destruction of the surrounding brain tissue.

The final goal of the treatment is to remove or cut off the blood supply to the AVM. This will prevent further growth of the AVM and eliminate the risk of rupture. Current treatment options of AVM are surgery to clip off the AVM, embolization, radiosurgery or a combination of these therapies.

The location and size of the AVM, as well as the patient's overall health and desire to undergo surgery, must be considered in the ultimate decision as to which treatment is recommended. The technical challenges of surgically excising AVMs located in the critical or deep portion of the brain make it crucial that the surgeon performing the operation is highly skilled and well versed in the appropriate approach to the AVM. The neurosurgeons at the Maxine Dunitz Neurosurgical Institute have extensive experience in surgically excising AVMs.

Embolization of AVMs involves placing a long, thin flexible tube into a blood vessel in the leg. This tube is advanced through the blood vessel to reach the AVM, and a glue-like material is then injected into the abnormal vessel, cutting off the blood flow to the AVM. Occasionally, embolization is used in combination with surgery to allow for an easier and less hazardous operation.

An acoustic neuroma is a benign tumor of the eighth cranial nerve - the vestibulo-cochlear nerve - in the posterior fossa. It manifests itself with sensorineural hearing loss. At the Department of Neurosurgery, our surgeons work closely with ENT surgeons at the House Ear Institute to determine the best surgical approach for patients requiring surgical treatment. When indicated, the most advanced treatments using stereotactic radiosurgery, including fractionated radiosurgery, is also available at the Department of Neurosurgery, allowing non-invasive treatment of acoustic tumors.

For more on acoustic neuromas, please see Acoustic Neuromas.

Chordomas are tumors of notochordal origin that may affect the axial skeleton anywhere from the coccyx to the base of the skull, in either the midline or paramedian position. The cranial and caudal extremes of the spine are most often affected.

There is no single surgical method for therapy or resection of these tumors. There are single-stage procedures that differ in the extent of the dissection and the area of optimum exposure. Surgical goals involve as complete a removal of the tumor as possible. The role of adjuvant radiotherapy thereafter is still subject to debate.

Continued development of skull base microsurgery combined with other minimally invasive endoscopic approaches may allow more complete resection. These innovative approaches developed and used by the neurosurgeons of the Maxine Dunitz Neurosurgical Institute involving craniofacial manipulation may be associated with greater disease-free survival.

Cranial extensions of head and neck cancers include squamous cell and basal cell tumors that can originate in the sinuses, salivary glands or orbits (the area behind each eye). Since these tumors do not differentiate between where the skull base starts and where the brain ends, in many cases they infiltrate the skull base.

One of the challenges is to resect the tumor without any disfiguring scars. This can be done by hiding all the scars either above the hairline, in the conjunctiva (inside the eyelid) or in the mouth.

For an appointment, a second opinion or more information, please call 1-800-CEDARS-1 (1-800-233-2771) or e-mail us.