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Skull Base Surgery
The Center for Complex Intracranial Surgery at Allegheny General Hospital is a world class treatment center in one of the leading teachings institutions in the United States. The center is directed by Khaled Aziz MD, PhD. We are offering hope for patients with skull base tumors, all variants of brain tumors, and cerebrovascular lesions including aneurysms and arteriovenous malformations.
Our team is highly skilled, equipped with the latest computerized technology, and uses the most sophisticated surgical devices. Our multispecialty team includes neurosurgeons, neuro-otologists, neuroradiologists, neuro-oncologists, and radiation oncologists. For skull base and brain tumors, we offer microsurgical resection, endoscopic assisted resection, and all variants of stereotactic radiation therapy. For cerebrovascular lesions, we offer microsurgical clipping, arterial bypass, endovascular coiling, embolization, stenting, and stereotactic radiation therapy for arteriovenous malformations. The team members perform individualized lesion specific evaluation and thorough pre-operative planning. We also have state of the art operative team and operating rooms. Post-operative recovery care is provided in our neuroscience intensive care units by our intensive care specialists and neuroscience nursing staff.
Skull base tumors that we treat include:
- Acoustic Neuromas
- Tumors of the sellar region (Pituitary adenomas, Craniopharyngiomas)
- Conditions and Associated Treatments
- How are meningiomas diagnosed?
- How are meningiomas treated?
- Acoustic Neuromas
- Associated Physicians/Staff
The following are some of the conditions treated at the AGH Center for Complex Intracranial Surgery:
Meningiomas are tumors growing from the protective membranes surrounding the brain and the spinal cord called the meninges (dura and arachnoid matter). Meningiomas are more common in females and represent 20% of primary brain tumors and 12% of spinal cord tumors. Meningiomas are usually benign and grow slowly. Less than 10% of meningiomas can transform into malignant tumors.
What are the presenting symptoms of meningiomas?
Symptoms vary according to the tumor location and size. They often present first with headaches and seizures, primarily due to increased intracranial pressure by the growing tumor. Weakness or loss of sensation of the arms or legs may occur with spinal cord meningiomas.
Different locations of meningiomas and symptoms
Convexity meningiomas are located on the surface of the brain. Presenting symptoms can be seizure, headache, numbness and/or weakness of one of the extremities, and visual changes.
Parasagittal meningiomas are tumors located close to the midline of the brain and can cause symptoms similar to convexity meningiomas.
Falx Meningiomas are tumors growing from a dural fold (falx) located between the two (right and left) hemispheres of the brain.
Olfactory groove meningiomas are located at the base of the frontal portion of the brain. They grow along the olfactory nerve fibers (responsible for the sense of smell) and run between the base of the frontal portion of the brain and the nose. These tumors usually grow large before clinical presentation. They cause loss of smell, headache, visual changes, and seizures.
Suprasellar meningiomas are located close to the optic nerves. They usually present with visual changes.
Sphenoid meningiomas grow along a bone inside the skull called the sphenoid ridge. Presenting symptoms include headaches, seizures, visual changes, and facial numbness when the tumor presses upon or infiltrates the cranial nerves of the cavernous sinus.
Cavernous sinus meningiomas are located in a venous structure located at the base of the brain called the cavernous sinus. The internal carotid artery is located within the cavernous sinus as will as the sixth cranial nerve (responsible for lateral movement of the eye). Cranial nerves three, four, and a portion of five are located at the outer aspect of the cavernous sinus. Cavernous sinus meningiomas present early with visual changes and facial numbness. Meningiomas in this location are usually treated with stereotactic radiation therapy.
Posterior fossa meningiomas are located at the base of the brain in close relationship to the cerebellum and the brainstem. This includes the cerebello-pontine angle, petroclival, tentorial, and foramen magnum meningiomas. These tumors present with symptoms due to compression of the brain, brainstem, cerebellum, and cranial nerves. Symptoms can include headache, facial numbness, pain (trigeminal neuralgia), visual changes, dizziness, vertigo, hearing disturbance, balance problems, difficulty walking, and weakness of extremities.
Intraventricular meningiomas are located in a fluid (cerebrospinal fluid) filled cavity inside the brain called the lateral ventricle. These tumors can block the cerebrospinal fluid and cause increased intracranial pressure causing headache and visual changes.
Orbital meningiomas are located around the optic nerve and usually present with visual changes.
Spinal meningiomas are located along the coverings layers around the spinal cord. Symptoms vary according to the site of the compressed area of the spinal cord. Symptoms can include back or limb pain, numbness or weakness of the arms or legs, and difficulty controlling bowel and bladder movements.
Your physician first reviews the presenting symptoms, medical history, and performs a clinical examination. Tests that can used to diagnose meningiomas include computerized tomography (CT) and magnetic resonance imaging (MRI) scans.
Treatment options for meningiomas depend upon the patient’s age, medical condition, tumor size, and location.
Observation and radiological follow-up?
Observation is a favorable option for the elderly or medically ill patient. Observation may also be appropriate for small incidentally discovered tumors. Neurosurgeons monitor tumor growth closely with serial MRI scans.
Surgery is a treatment option for meningiomas. Sophisticated technology and image guidance allow us to precisely locate meningiomas and confirm the degree of resection during the operative procedure. Microsurgical, endoscopic, and skull base techniques allow us to more safely access tumors in critical locations. Total microsurgical resection can be achieved for some tumors based upon the location and relationship to surrounding cerebrovascular structures. Subtotal resection may also be achieved for optimal safety and functional outcome of the patient. Residual tumors can be treated with stereotactic radiation therapy.
Stereotactic Radiation Therapy
Stereotactic radiation therapy may be a therapeutic option offered to the elderly and medically ill patients. Stereotactic radiation therapy is also used to treat residual tumor after surgical resection. Treatment can be a single dose of stereotactic radiosurgery or multiple doses (fractionated) radiation therapy. The radiation effects occur over a period of time and may stop tumor growth and allow tumor shrinkage.
Acoustic neuroma (also called Vestibular Schwannoma) is a benign tumor that grows from Schwann cells covering the vestibulocochlear nerve (eighth cranial nerve). The incidence of acoustic neuroma is 10 people in one million. It is more common in women than men, and affected patients are usually diagnosed between the ages of 30 and 60 years. Acoustic neuromas are classified according to size into small (less than 1.5 cm), medium (1.5 to 3 cm), or large (more than 3 cm).
The vestibulocochlear nerve is responsible for hearing and balance. The cochlear portion is responsible for hearing and the vestibular portion is responsible for balance. The vestibulocochlear nerve is located close to the facial nerve in a bony canal called the internal auditory canal. The facial nerve, also called the seventh cranial nerve, controls the muscles of the face. Patients with large acoustic tumors can suffer from facial muscles weakness. As the tumor grows it extends into a space between the cerebellum and the brainstem called the cerebello-pontine angle. This can cause compression of the trigeminal nerve, also known the fifth cranial nerve, resulting in facial numbness.
The most common presenting symptom is hearing loss in the affected ear, which may not be recognized or is mistaken as normal changes with aging. Tinnitus (ringing ears), dizziness, unsteadiness, headache, and facial numbness are also common symptoms.
How are acoustic neuromas diagnosed?
It is important to contact your primary care physician for ringing ears, dizziness, unsteadiness, or decreased hearing. This will subsequently lead to a thorough clinical evaluation by a neuro-otologist and neurosurgeon. Neurological examination is followed by neuro-otologic tests:
- Audiogram to evaluate hearing in both ears
- Occulonystagmogram to evaluate balance
- Computed Tomography (CT) scan is a noninvasive X-ray test to evaluate changes in the bony structure of the internal auditory canal.
- Magnetic Resonance Imaging (MRI) scan with and without intravenous contrast dye is a safe noninvasive radiological test that provides detailed images of the brain and cranial nerves.
What are the treatments options for acoustic neuroma?
Early recognition, diagnosis, and treatment of acoustic neuromas are important. Treatment options include observation, surgical resection, and stereotactic radiosurgery (SRS). Definitive curative treatment for acoustic neuroma is often surgical removal by our neurosurgery and neuro-otology team.
Observation: Small acoustic neuromas that cause mild symptoms may be observed and followed with serial MRI scans. The frequency of MRI scans is dependent upon the patient’s age and overall medical condition.
Surgery is a curative treatment option. The goal of surgery is total tumor removal and preservation of both facial nerve function and hearing. There are multiple surgical approaches to remove acoustic neuromas based upon tumor size, location, and hearing status of the patient.
Surgical approaches include:
Middle fossa approach for small intracanalicular tumors which allows preservation of facial nerve and residual hearing function.
Suboccipital approach for small and large tumors allows preservation of facial nerve function and residual hearing functions when possible.
Translabyrinthine approach for patients with non serviceable hearing function allows preservation of facial nerve function, but does not preserve hearing function.
Stereotactic Radiosurgery is an outpatient treatment option. Stereotactic radiosurgery is a single dose of highly concentrated and precisely focused beam of radiation to treat brain tumors. It is safe and effective treatment without surgical incision. We temporarily attach a metal frame to the patient's head and subsequently perform an MRI. The MRI images are reconstructed in three dimensions. Our team of neurosurgeons and radiation oncologists precisely mark the exact tumor boundaries. Radiation oncologists then use highly focused beams of radiation to target the tumor. The effects of radiation treatment dose occur over a time period and do not show immediate results. This radiation dose will gradually stop tumor growth in the majority of cases and occasionally shrink the tumor.
- Matthew Quigley, MD
- Andrew Ku, MD
- Robert Williams, MD
- Douglas Chen, MD
- Todd Hillman, MD