Skull base surgeons at the Center for Cranial Base Surgery at the New York Head and Neck Institute of the North Shore-LIJ Health System treat tumors, vascular (blood vessel) problems, infections and many other conditions that may begin at or spread to the cranial base.
Cranial base tumors can often be asymptomatic (without symptoms) until they compromise neighboring structures, so they are often found at advanced stages. The symptoms that are produced are often dictated by the size and location of the tumor in the skull base and by the nearby structures. There are also some tumors that are identified incidentally on CT scan or MRI as a result of a generalized complaint of headache.
The anatomic site of the tumor's origin and growth is the most important factor in predicting symptoms. For example, squamous cell cancers of the nasal cavity present themselves differently from temporal bone lesions, primarily because of location rather than how the tissue appears under a microscope.
The anterior (front) skull base and involved paranasal (next to the nose) sinuses are closely related to the orbit (eye socket) and to the cribriform plate (a very thin plate of bone at the top of the nose where fibers of the olfactory nerve, nerve for smell, exit the brain).
If the tumor is predominately in the nasal cavity, initial symptoms may include:
- Nasal congestion
- Epistaxis (bloody nose)
- Anosmia (inability to smell)
- One-sided otitis media (fluid in the middle ear behind the ear drum)
Tumors from the front skull base can cause visual disturbances such as:
- Diplopia (double vision)
- Proptosis (bulging of the eyeball)
- Epiphora (drooping of the lower lid with eye drying)
- Vision loss
The close vicinity of the cribriform plate causes the changes to taste and smell. Neurologic findings become apparent when tumors erode into the ptyregomaxillary space (a space where the internal muscles closing the jaw attach to the skull base), epidural space (space between the skull and the outer tough covering of the brain, dura) or brain tissue itself.
The effects of the erosion of surrounding structures include:
- Cranial neuropathies (disease or non-function of the twelve large, paired nerves exiting the base of the brain)
- Frontal lobe symptoms such as alterations in personality.
Middle cranial base lesions can cause pituitary and hypothalamic (the part of the brain that signals the release of hormones to control the other endocrine glands throughout the body) abnormalities such as failure of the pituitary gland to function and excessive thirst due to lack of a hormone that helps the body retain water.
Alternatively, they can affect the optic chiasm, which is the structure where the optic nerves cross at the front of the base of the brain. Patients can experience facial pain, dysesthesia (disturbance of sensation) and nerve palsy (weakness). Tumors of the lateral (side), middle cranial base can affect the trigeminal nerve, lateral orbit, and infratemporal (below the temporal bone) fossa though both facial deformity and mouth and throat masses.
Tumors of the temporal bone and cerebellopontine angle (angle between the brainstem and the cerebellum), the two small lobes below and behind the big brain lobes (cerebrum) that smooth muscular movements and coordination can cause symptoms such as:
- Imbalance (vertigo)
- Pulsatile tinnitus (ringing in the ears in time with the pulse)
- Asymmetric hearing loss (one ear with greater hearing loss than the other)
- Otorrhea (draining ear)
- Vague headache
- Facial twitching or numbness
The hearing loss involved can either be conductive (due to disturbance of the small bones conducting sound from the ear drum to the inner ear) or high or low frequency sensorineural (when the inner ear nerve produces nerve impulses the brain interprets as sound), depending on the location and type of the tumor. If the top of the intracranial part of the temporal bone is involved, then the VIth cranial nerve can become involved and double vision can occur.
Tumors at the back of the skull base near the lower brainstem or jugular foramen will cause deficits of the lower cranial nerves controlling sensation in the back of the throat, voice box, neck muscles and tongue movement.
The following is a partial list of the tumors and other problems treated at the Center. Patients are urged to contact the Center for Cranial Base Surgery for questions regarding any concerns that they may have that may be related to a problem of the skull base.
Acoustic Neuroma (Schwannomas)
Acoustic neuromas (schwannomas) are benign tumors that grow from the cells that form around the fibers of the cochlear nerve (hearing) or the vestibular nerve (balance), which unite to form the vestibulocochlear, or the acoustic nerve. This combination of nerves to form one nerve runs from the inner ear, deep inside the temporal bone -- which makes up the side and base of the skull above, below, and behind the ear-- to the brainstem. There are two temporal bones, one on each side of the head.
Next to the vestibulocochlear nerve is the facial nerve, which controls the muscles of the face. The vestibulocochlear and facial nerve both run through the same hole in the top of the temporal bone next to the brainstem. As an acoustic neuroma grows, it presses on the other nerves around it in the hole, and can produce symptoms that include hearing loss on the side of the tumor and tinnitus (ringing in the ear). As the tumor grows, or if it starts in the vestibular part of the nerve, the person will experience balance problems or vertigo. Finally, if it is very large, the patient may develop facial paralysis of one side, as well as hearing loss, tinnitus and vertigo.
Adenocarcinoma (malignant cancer from gland tissues) is found to be a common tumor of the sinuses, forming on the lining tissues, which are the air-filled areas that make up the inside of the facial bones. The greatest risk factor for getting one of these types of sinus cancer seems to be inhaling high levels of wood and leather dusts.
These tumors are traditionally classified as low grade and high grade. The low grade types are more likely to come back in the area where they began. The high grade malignancies can metastasize (spread to other areas). Much like squamous cell cancer (another type of malignant tumor starting in the sinus lining), adenocarcinoma often responds to the addition of radiation therapy and/or chemotherapy to surgical removal.
Adenoid Cystic Carcinoma (ACC)
Adenoid cystic carcinoma (ACC) is a slow growing, neurotropic (tends to grow along nerves), infiltrative tumor that is likely to appear in the sinonasal tract. It often has a long, slow course ultimately spreading to the bones, the lungs and the brain.
The most common ACC symptoms are:
- facial or dental pain
- nasal obstruction
- epistaxis (nose bleeds)
- facial numbness
- cranial nerve palsy (weakness in large nerves at base of the brain that control vision, smell and speech)
Adenoid cystic carcinoma occurs most often in middle-aged women. Unfortunately, these tumors of the nose and sinuses are often found at a later stage and tend to be more aggressive and spread. The survival rate of this type of tumor is largely based upon how much of the tumor is removed in a cranial base resection, the extent of invasion around the nerve and how malignant the tumor tissue appears under the microscope. Treatment is based upon whether all of the tumor can be removed at the time of surgery. If all of the tumor could not be removed at the time of surgery, radiation is added following surgery to be sure that all of the cancerous cells are gone.
Angiofibromas / Juvenile Angiofibromas
Angiofibromas, or most commonly, juvenile angiofibromas, are benign fibrovascular tumors (fibrous and blood vessel tissue origin) that occur almost always in teenage males. They often originate in the back and side walls of the nasal cavity near the hole in the skull base where nerves or blood vessels pass to the brain, and they grow in all directions. Patients may experience symptoms such as nasal obstruction and recurrent severe nosebleeds.
The standard treatment is preoperative embolization (injection of materials into the arteries supplying blood to the tumor to plug the arteries and decrease blood loss during tumor removal), followed by surgical excision. Radiation can be used for bigger growths. Chemotherapy and hormonal treatments have also been used with some success.
The cavernous sinus is a small blood-filled space on both sides of the skull base behind the eyes. Each sinus contains the carotid artery (the large artery that supplies blood to the head)
Several disorders that may affect the cavernous sinus are:
- meningiomas (benign tumors of the brain coverings)
- schwannomas (a benign tumor of the cells that insulate nerve fibers)
- aneurysms (bulges or weakened areas of the wall of arteries that may cause the artery to rupture)
- pituitary tumors (tumors of the master gland at the base of the brain controlling the secretions of other glands such as the thyroid and adrenal)
- infections of the face and eyes that have spread into the cavernous sinus
Chondrosarcomas are very similar to chordomas (listed below) in behavior, presentation and treatment. They affect similar age groups and are slow growing and advanced. They invade the vital neurovascular (nerve and blood vessel) structures. Chondrosarcomas are formed in the areas where the cranial bones are joined together and next to the area where the pituitary gland is found. They have a destructive growth pattern, so local control is the goal in treatment. Similarly, standard X-ray and proton (high energy) radiation plays an important role in the treatment of both primary and recurrent disease along with surgical removal.
Chordomas are rare brain tumors that involve the base of the skull. These primary, malignant bone cancers are thought to grow from the remains of notochordal cells. These cells are embryonic and form the structure around which the spinal column grows, before they eventually break down and disappear. However, chordomas are thought to grow out of notochordal cells that did not disappear.
The most common symptoms of chordomas are pain and neurological changes. Brain tumor-like symptoms of skull base chordomas are headache, neck pain, double vision or paralysis of the facial muscles.
Cranial Base Metastases
Cranial base metastasis is the spreading of distant tumors to the cranial base. The most common tumor metastases come from the breast, lung and prostate. These often occur after there are other bone metastases, and it is thought in this instance that the cancer cells are spread through the bloodstream.
These lesions (metastases) most often produce symptoms such as pain and cranial nerve palsies (weakness). The site of metastases (spread) dictates the clinical symptoms.
The patient's prognosis (outlook for cure) depends on a number of factors:
- the type of tissue the tumor came from
- how fast the tumor grows
- the site of the tumor
- where it has spread
- whether it can be surgically removed
Radiotherapy is often the main treatment, as it provides pain relief and reduction in cranial nerve weakness. Surgical options are only resorted to in cases where there is only a single growth at the cranial base that has spread from the primary tumor elsewhere.
Esthesioneuroblastomas are also known as olfactory neuroblastoma, esthesioneuroepithelioma and esthesioneurocytoma. This tumor is most likely from embryonic tissue that forms the brain and spinal cord and arises from the actively growing bottom layer of the olfactory epithelium, which is the nerve for smell behind and above the bridge of the nose at the base of the front part of the brain.
It usually grows in the top of the nasal cavity lining the septum's cribriform plate (a thin bone at the base of the skull where the olfactory nerve fibers go into the top of the nose) and superior turbinate (the highest of three scroll-shaped bones that are on the side walls of the nostrils) and resembles a grape-like mass. The spread of this cancer to the lymph nodes or other areas of the body is rare when the patient is first seen, but tumors in the neck can develop. Several staging classifications -- ways to describe the size and spread of cancer to predict survival and direct treatment -- are based on anatomic extent of disease or how the tissue appears under the microscope.
Aggressive tumors and those that invade the sphenoid sinus, orbit (eye socket), and dura (outer covering of the brain) are known to have a poorer prognosis. Treatment includes both surgery and radiation with chemotherapy of questionable impact. Some doctors recommend sequential radiation and chemotherapy followed by salvage (surgery done after other treatments have failed) craniofacial resection (removal of portions of bone at the base of the skull and upper face).
Facial Pain Syndromes
Facial pain syndromes are called trigeminal neuralgia. Patients have very sharp pain on only one side of the face for short periods of time, with some describing it as an “electric shock,” while others call it “knife-like.” The location, intensity and symptoms are the same each time it happens. One of the most important symptoms of facial pain syndromes is that the pain is separated by periods of no pain, even if for short periods of time.
Although the exact causes of trigeminal neuralgia are not known, it is thought to be most likely caused by a loop of a blood vessel leaning against the trigeminal nerve (nerve providing sensation to the face) where it enters the brainstem.
Meningiomas are one of the most common skull base tumors. Meningiomas are benign, slow-growing tumors that begin at the covering of the brain and continue growing between the brain and the skull. As they grow, they press against the brain and the areas around it, causing symptoms that mimic a brain tumor (tumors that began in the cells of the brain) such as imbalance, weakness of the arms and legs and headaches. Meningiomas that compress nearby cranial nerves cause symptoms that include double vision, numbness, weakness, pain in the face or hoarseness. There are often no specific symptoms of meningiomas other than headache.
Mucosal melanoma (cancer of skin pigment cells or lining tissue of the nose and sinuses) of the nasal cavity represents only 1-2 percent of all melanomas, but is the most common site of occurrence outside of sun-exposed areas of the skin. Like most tumors of the sinuses, melanoma usually begins in the maxillary sinuses (cheek bone sinuses) and ethmoid sinuses (between the eyes and nose). The symptoms of mucosal melanoma include frequent bloody nose, nasal discharge and drainage. Rarely, because of orbital (eye socket) involvement there may be proptosis (bulging of the eyeball outward) and eye pain.
For treatment, wide local resection is most commonly attempted, with radiation in some cases. Excision is sometimes performed to relieve certain symptoms but is generally considered palliative (treatment done for patient comfort rather than a cure). Mucosal melanoma is a rare, aggressive tumor with a high recurrence rate if removed. The survival rate is about five years.
Paragangliomas form out of cells in the embryo from which the brain and spinal cord develop that arise along arterial vessels and cranial nerves in the head and neck. They are generally benign, slow growing tumors that, in the cranial base, can originate from the middle ear space (glomus tympanicum) causing a unique symptom called "pulsatile tinnitus" which is hearing the sound of your own pulse in the ear at all times.
Jugular lesions form in the lateral temporal bone and can cause bony destruction at the jugular bulb (bulbous area of the internal jugular vein where it leaves the skull). Tympanic (ear drum) paragangliomas can appear as polyps on otoscopic exam, as well as bluish lesions that blush on pneumotoscopic exam (air pressure applied against the ear drum while looking in the ear). The symptoms include hearing loss, bloody otorrhea (ear drainage) and cranial nerve defects.
Paragangliomas are not qualified as malignant unless they spread to other locations. Primary treatment is based upon removal of both extra and intracranial components and precise microscopic surgical resection. Preoperative embolization (injection of materials that plug the vein or artery to limit blood loss during tumor removal) is applicable in many instances.
Pediatric tumors of the cranial base differ from those in adults with regard to the overall incidence (they are very rare), the differential diagnosis and commonness in males.
The list of pediatric lesions includes:
- encephaloceles (herniation of brain out of the coverings)
- fibrous dysplasia and esthesioneuroblatoma (tumors of the nerve for smell) at the anterior skull base
- craniopharyngioma (tumors at the junction of the skull base and upper throat)
- angiofibromas (tumors of blood vessels and fibrous tissue) in the middle cranial base
- cholesteatomas (growths of skin like cells in the temporal bone)
- sarcomas of the posterior skull base
Pituitary Tumors or Pituitary Adenoma
Pituitary tumors (pituitary adenoma) are tumors that grow in or on the pituitary gland, which is a pea-sized gland located underneath the front part of the brain behind the bridge of the nose. The pituitary gland stores, releases and controls a normal balance of the hormones that control the thyroid gland, the adrenal glands, the ovaries in women and the testes in men.
These tumors are almost always benign and either produce too much or too little of a certain hormone. More often, pituitary tumors may not secrete any hormone but produce symptoms because of their enlarged size. The most common symptoms of tumors in the pituitary gland are diplopia (double vision) or partial loss of peripheral (side) vision called hemianopsia.
Sinonasal Undifferentiated Carcinoma (SNUC)
Sinonasal undifferentiated carcinoma (SNUC) is a rare and aggressive malignancy only recently categorized. The cells of the cancer look so abnormal under the microscope that it is difficult to tell what type of cancer it is.
Unlike many sinonasal tumors, patients often exhibit early symptoms like pain, bulging eyes and nerve problems, which develop as a result of rapid, extensive local involvement of the eye socket and cranial base.
This type of tumor spreads to the lymph nodes in up to 20 percent of patients by the time they see a doctor, while spread of the cancer away from where it began are rare. Treatment using radiation, surgery and chemotherapy has been tried but remains ineffective.
As with many skull base tumors, the goals of treatment are to control local disease, preserve vision and limit significant intracranial (within the skull) extension. Surgery including craniofacial (removal of the bones of the skull base and face) resection and maxillectomy (removal of the cheek bone and sinus under it) are almost always incorporated into the treatment plan along with radiation and/or chemotherapy.
Sinus and Nasal Tumors
Sinus and nasal tumors make up roughly 3 percent of head and neck cancers and are most common in males in their 60s (the rate of occurrence of these cancers is particularly high in Japan). The most common sites where they occur are the maxillary sinus, which is under the cheekbone, nasal cavity and ethmoids, which are sinuses between the eyes and nose. Less than 1 percent arise from the frontal and sphenoid sinuses (under the forehead and a single large sinus at the center of the skull base).
Exposure to the dust of nickel, wood or leather, and asbestos is linked to this type of cancer. Also, tobacco smoke and snuff may be causes of these cancers, as they are found more commonly in people with exposure to these substances.
Squamous Cell Carcinoma
The most common malignancy of the sinuses and nasal cavity is squamous cell carcinoma (a type of cell that lines the sinus cavities), which typically strike males in their 50s. These tumors arise from silent locations and usually cause very mild symptoms, if any.
The most common site is the maxillary sinus (under the cheekbone) with growth out of the sinus toward the back and above the sinus into the skull base. These cancers may require a craniofacial or skull base resection in addition to removing the cheekbone. The cancer is locally destructive and spreads to tissues in the area and lymph nodes. When first seen by the doctor, 10 percent of patients have lymph node metastases (spread of cancer cells) to the neck.
Another 20 percent develop cervical node (lymph glands in the neck) metastases. If radiation is not given in addition to surgery, one of the nerves supplying sensation to the middle of the face must be followed with CT scans to be sure the cancer is not growing along this nerve as it passes through the roof of the maxillary sinus (floor of the eye socket) onto the face.
Vascular lesions treated include aneurysms, which are balloon-like bulges in an artery caused by weakening of the artery wall that may result in rupture of the artery, and malformations of the veins and arteries – known as arteriovenous malformations. AVMs are abnormal connections between veins and arteries.