Skull Base Tumors
refers to a group of tumors that have a tendency to grow along
various regions of the bottom part of the Skull, mostly on the
inside, but occasionally, also on the outside of the Skull. The
Skull Base area separates the base of the Brain from the Skull.|
Diseases of the Skull Base are rare, but potentially life
threatening and, were considered inoperable because of their
sensitive location, as well as the possible effects surgery could
have on Brain function and complex senses, such as hearing, vision
Treatment for these lesions is different from other tumors, both
in the surgical approach to their removal and the multi-disciplinary
team of surgeons and physicians required to successfully manage
The Skull Base, upon which the Brain's undersurface rests, has
three main regions. The Anterior (front) Cranial Fossa is the
region located above the eyes and includes structures such
as: the olfactory bulbs, the nasal cavity, and the Cranial
Nerves (2, 3, 4 & 6) that control vision, as well as movement of the
eyeballs. The Middle Cranial Fossa is the region containing the
dense, boney Petrous Ridge, and houses the Internal Carotid
Artery, along with sections of the Cranial Nerves (5 & 7)
that control chewing and facial sensation. The Middle Cranial Fossa
also contains the Cavernous Sinus, an extremely difficult structure
from which to remove tumors. The Posterior (back) Cranial Fossa is
where the Brain Stem and Cerebellum are located. Of
the 24 highly specialized Cranial Nerves, which control many vital
functions of our head and neck, 18 (Cranial Nerves 3, 4, 5, 6, 7, 8, 9,
10 & 12 two on each side of the skull) originate within this
Posterior Cranial Fossa. Skull Base Tumor Surgeons are often called
upon to manage tumors that affect the Facial, Cochlear and Vestibular
Cranial Nerves which are respectively responsible for facial
expression, hearing, and balance. These 4 nerves are all located within a
narrow passage traveling inside the dense Petrous Bone called the
Internal Auditory Canal. Another vital structure in this region is
the Jugular Vein.
For decades, tumors within the Skull Base's delicate and complicated bone
anatomy were difficult for surgeons to access safely. Patients with
Skull Base Tumors often had a poor prognosis. Advances in
both technology and microsurgical techniques have dramatically increased
the Skull Base Tumor Surgeon's ability to remove and successfully manage
Skull Base Tumors.
There are several ways to classify Skull Base Tumors. One common
method is to arrange them by the region that they most often affect. For
example, Anterior Skull Base Tumors may be malignant or benign.
The malignant tumors in this group include tumors arising
in the nasal cavity and paranasal sinuses (such as
Juvenile Angiofibroma, Esthesioneuroblastoma, Inverted Papilloma, Lymphomas
and Nasopharyngeal Carcinoma).
Other malignant tumors in this group include
Orbital Gliomas and other
orbital tumors, rhabdomyosarcomas, and osteogenic sarcomas. The
benign tumors that occur in the Anterior Skull Base
(see Figures 2 & 3 and 5 through 7 below) and
Tumors that are unique to the Skull Base of the Middle Cranial Fossa
are often benign. These tumors include
Temporal Bone Tumors, Cholesteatomas, Enchondromas and Trigeminal Nerve
tumors (such as Neurofibromas.)
Figure 1A (Left): MRI Scan (Coronal View). This is a partially
cystic Left Trigeminal Neurofibroma (Arrow) that extends through
the Skull Base.|
Figure 1B (Right): MRI Scan (Gadolinium "Enhanced"-Transaxial View)
The Trigeminal Neuroma tumor is mostly cystic with an "Enhancing"
(Arrow) portion that is "solid".
Both benign and malignant tumors can affect the Skull
Base of the Posterior Cranial Fossa. Of the benign tumors
Chondromas, and Chordomas
are the more common while Chondrosarcoma is the malignant tumor
that occurs in this area.
Another way to classify these tumors is by their area of origin.
For example, Primary Tumors arise from the cells of the
anatomical structures in the Skull Base location. Primary Tumors,
arising from inside the Skull such as
and Pituitary Tumors,
Ossifying Fibromas and Osteoid Osteomas are often Benign.
Secondary and Metastatic Tumors generally come from outside
the Skull such as tumors arising in the nasal cavity and
paranasal sinuses (Lymphomas, Juvenile Angiofibroma,
Esthesioneuroblastoma, Inverted Papilloma, and Nasopharyngeal Carcinoma).
Other malignant tumors in this group include
and other orbital tumors, Rhabdomyosarcomas, and Osteogenic Sarcomas.
Nasopharyngeal Carcinoma is the most common Skull Base lesion, which
along with tumors such as Squamous Cell Carcinoma or Adenoid Cystic
Carcinoma and Esthesioneuroblastoma (also called Olfactory Neuroblastoma),
may extend intracranially through the thin bone of the cribriform plate,
which is a part of the Anterior Skull Base.
The patient's symptoms and signs depend on the structure(s) impinged
upon by the tumor. The Skull Base is a complex area, through which traverse
the Cranial Nerves that carry signals to and from the Brain. It is these
Cranial Nerves, as well as the Brainstem, that are at risk to involvement
and damage by the Skull Base Tumor. Although Skull Base Tumors
are "outside" of the Brain, they can affect many important functions
such as taste, vision, hearing, swallowing, facial movement and
hormonal balance. Because most tumors grow slowly, symptoms
may be present for years before the correct diagnosis is made.
Tumor location determines the structures that are affected.
Tumors in the Anterior Skull Base may cause dysfunction of the
Olfactory or Optic Nerve, resulting in loss of smell
and taste, or vision in one or both eyes. Tumors in the Middle
portion of the Skull Base may cause eye muscle palsies
and loss of sensation or painful sensations in the face.
Symptoms from tumors in the Posterior Skull Base may include
loss of hearing, imbalance, or difficulty swallowing.
Figure 2A: Coronal View CT Scan series showing a Tuberculum Sellae
Meningioma Involving both Carotid Arteries (L>R) (Arrows).|
Figure 2B: Sagittal View CT Scan series of this Skull Base Meningioma
(Same patient as 2A and Operative Photos in Figures 3 A&B below).|
Left: The Arrow indicates the Right Optic Nerve which has an
intimate relationship to the Tumor.
Center: The Arrow indicates the Sphenoid Sinus.
Right: The Arrow indicates the Left Optic Nerve and its
relationship to the Tumor.
Figure 3A (Left): Operative Photo-Same patient as Figures 2A & B -
The tumor partially encircles both the Left Optic Nerve and the
Carotid Artery. The nerve is compressed from below and is displaced
Figure 3B (Right): The tumor has been completely removed. The Left
Carotid Artery, Left Optic Nerve and Chiasm are well seen. The
Right Optic Nerve is further to the right of the far right arrow.
The investigation of any Skull Base Tumor must include some form
of Neuroimaging (CT and/or MRI scans). Once the presence of a
tumor of this type is made, patients are generally referred to a center
specializing in the care of these unique problems. Often times,
additional specially designed CT and MRI scans are required by the
treating team of physicians and surgeons. The following sophisticated
investigational techniques are frequently required by a Skull Base
Tumor Team. (See the list below under "TREATMENT")
CT Scan. Additional vital information regarding the Brain and
Skull require that thin cuts, along with Sagittal and Coronal
reconstructions, be obtained in order to determine the extent of the
abnormalities of the bone of the skull and calcifications in the tumor.
3-D reconstruction of the skull and tumor provide exquisite details for
the treatment team. CT Angiography can be used to provide some detail
of the blood supply to the Brain and tumor.
MRI Scan. Studies done, with and without gadolinium (the "contrast
agent"), are essential in order to evaluate the structure of the
tumor and its relationship to vital Brain centers. Newer software
programs allow for fine details of the Brain's anatomy to be highlighted
and magnified, thus providing vital anatomical detail. In some instances,
Magnetic Resonance Venography (MRV), as well as MR
Angiography (MRA), may be useful to assess the patency of venous
structures and arteries.
Cerebral Angiography is an important Neuroadiological procedure,
particularly if the tumor encroaches on the Carotid or other major
Intracranial Arteries or a major venous sinus. This can also help
assess whether arteries and venous sinuses are patent and
whether pre-operative embolization (obstruction) of the tumor's
blood supply is feasible.
Neuroradiologists, specialists in Neuroimaging interpretation, are vital
members of the treatment team at this point in the investigation of
Skull Base Tumor patients. They use the various Neuroimaging
techniques mentioned above to help the entire treatment team to understand
the anatomical complexity of these tumors. Since these tumors frequently
develop a robust blood supply, Interventional Neuroradiologists
are available with techniques designed to reduce or eliminate the
tumor's blood supply prior to initiating any definitive surgical
therapy. This is a preparatory step for surgical intervention,
which has helped reduce blood loss during operations.
Other tests to assess hearing, balance, phonation and vision may require
specialized technicians and physicians from other disciplines. This is
one area of medicine where patients benefit from having a team of
experts working together to solve these complex problems.
The goal of therapeutic intervention is to maximize the functional
outcome of the patient, while minimizing their morbidity. Only a
team approach can accomplish this. The multi-disciplinary
Skull Base Tumor Team, which includes specialists from Neurosurgery
and many other disciplines, offers patients the best of care for these
very difficult cases. The composition of a Skull Base Team
varies depending upon the nature and location of the tumor.
Among the specialists that may be involved in the diagnosis and treatment
of patients with these lesions are the following:
Many factors should be considered in making a final decision about the
appropriate form of treatment. No single approach is suitable for every
patient. In dealing with these tumors, the Skull Base Tumor Team
acquaints the patient with the benefits, risks and limitations of each
of the available treatment alternatives; so that the patient and their
family can make a well-informed decision about treatment that they
For a discussion of Treatment Alternatives either alone or in
combination with Skull Base Surgery please consult our
SKULL BASE TUMOR section.
Most Skull Base Tumors are approached surgically through a
craniotomy, a procedure in which the Neurosurgeon makes a temporary
opening in the skull as close as possible to the tumor site. The
basic concept of Skull Base Surgery is to approach the tumor from the
undersurface of the Brain and tumor, or from the side, by removing
specific parts of the bone of the Skull Base. This permits exposure of the
tumor with little or no retraction of the Brain.
- Craniofacial Plastic Surgeon
- Interventional Neuroradiology
- Plastic Surgeon (including free-flap reconstruction)
- Radiation Oncologist
- Ophthalmic Plastic Surgeon
- Oral Maxillofacial Surgeon
- Neurological Intensive Care Physician
In other cases, such as with many Acoustic Neuromas and Meningiomas,
the tumor can be completely removed with acceptable risks. Among
the considerable advances in modern Skull Base tumor surgery is the
opportunity to PRESERVE HEARING FUNCTION as well as FACIAL NERVE
FUNCTION in more patients with Acoustic Tumors.
In other patients, where the tumor is intertwined with important nerves
and arteries, it is wise to consider removing only that part of the tumor,
which can be removed without damaging the vital arteries and nerves. The
remaining part of the tumor that is intricately involved with the
arteries and nerves can, subsequently, be treated with Focused Beam
Radiation therapy (a specialized form of radiation treatment called
Radiosurgery.) In some cases this Radiation therapy is
preferable to surgery since some tumors cannot be approached, nor
substantial amounts of the tumor removed, without causing a significant
Figure 4A (Left): MRI Scan (Transaxial View) A large Left Acoustic
Neuroma (Arrow) with considerable pressure upon and distortion of
the Brain Stem.|
Figure 4B (Right): MRI Scan (Same Patient) Post-operative Minimally
Invasive complete resection. (Note the reversal of the Brain Stem
compression.) The 7th & 8th Cranial Nerves (whose function was
preserved) can be seen entering the Internal Auditory Canal which
has been opened at surgery.
In order to fulfill the previously stated requirement to maximize
the functional outcome for the patient, while minimizing the morbidity,
the aggressiveness of the surgical approach must be adjusted according
to the potential impact of the operation on the patient's quality of
life. We recognize that many of these tumors are benign and
often are slow growing. It is frequently in the best interests of
the patient to attempt to remove only part of the tumor, without
adding any major new neurological deficit to an already difficult
There are several highly advanced technologies that are now
available to assist the Skull Base Tumor Team in the management of
these cases. Computer-assisted tumor removal is a surgical
method that uses information obtained from state-of-the-art computer 3-D
imaging techniques, to form computer-generated models of the tumor.
Neurosurgeons, together with the other Skull Base Tumor Team
members, can then plan and simulate the surgical procedure prior to
operating, with the goal of reaching the brain tumor using the safest and
least invasive method possible. Among the other technological advances are
the Minimally Invasive Microendoscopic and Microneurosurgical
techniques, which incorporate smaller incisions and thus less
injury to normal Brain tissue, less blood loss and less post-operative
pain compared to more traditional surgery.
Minimally Invasive approaches allow the Neurosurgeons to utilize a
tiny endoscope with a camera on the end, which is inserted through the
nostril, eyebrow, or other area of the face into the Skull Base. The
camera provides surgeons with a panoramic view, and in some cases, allows
them to remove the tumor completely.
Endoscopic Brain Surgery
is not appropriate for all cases of Skull Base Tumors although
it can be particularly beneficial in treating certain types of benign
Figure 5A (Above): MRI Scan- Coronal View - of an ANTERIOR Skull
Base Meningioma in a 70 year old lady.|
Figure 5B (Left): MRI Scan-Transaxial View
Note: Same patient as Figures 5A, 6 & 7.
Figure 6A (Left): Dr. Lazar performing a Minimally Invasive
Endoscopic Assisted Image Guided removal of the Anterior Skull
Base Tumor using a "KEY-HOLE SURGERY" Craniotomy approach through
an "eyebrow" incision.|
Figure 6B (Right): Post-operative CT Scan demonstrates the small
Figure 7: 1 Month post-operative photograph of the 70 year old lady
represented in Figures 5 A&B and 6 A&B.|
This patient was discharged from hospital on the 2nd post-operative
Note: The early post-operative scar at the right nasal bridge.
The Neurosurgeons involved with Neurosurgical Consultants' Cranial Base
Surgery Program specialize in the treatment of Complex Tumors, Pain
Syndromes, and Congenital Defects at the Base of the Skull.
Our philosophy is to use
Minimally Invasive Microsurgical and/or Microendoscopic
techniques whenever possible. Dr. Lazar and his colleagues use
Endoscopic and Minimally Invasive approaches to remove a variety of
tumor types from various locations including Transsphenoidal Surgery
for Pituitary Tumors, Glabellar approaches (through an eyebrow incision)
for Anterior Skull Base Meningiomas, Pterional Burr Hole access for the
Endoscopic resection of Giant Arachnoid Cysts of the Middle/Anterior and
Posterior Cranial Fossa as well as for different approaches for Clival
The Neurosurgical Consultants' Skull Base Surgery Program
particularly focuses on treatment for the following tumors:
For additional information or to have your Skull Base Tumor
reviewed, please see (on this website)
ARRANGING A CONSULTATION
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This page last edited on 2/17