Skull Base Tumors

Overview

Skull base tumors are tumors that originate along the base of the skull or just under the skull base in regions such as the sinuses. Many are noncancerous (harmless) and develop slowly over time. A skull base tumor can be malignant in rare situations, which means it can spread to other regions of the body.

Skull base tumors may not cause symptoms until they reach a certain size. Symptoms differ from person to person based on the location of the tumor and its rate of growth. Symptoms of a skull base tumor may include: facial discomfort or numbness, facial weakness or paralysis, headache, recurring sinus issues, nosebleeds, vision loss, hearing loss, tinnitus, difficulty swallowing and recurrent choking. Swells on the neck

Because each tumor type and each patient are unique, professionals on the skull base team carefully customize diagnostic procedures and treatment regimens in each situation to give the best care for each patient.

Patients with skull base tumors benefit from cutting-edge technologies and therapies, many of which are only offered in a few places throughout the country. Minimally invasive surgery, proton treatment, innovative radiation delivery systems, advanced reconstructive operations, chemotherapy, targeted therapy, and immunotherapy may be advised.

Is a Skull Base Tumor a Brain Tumor?

No, it's not the same as brain tumors, although it might be developing in a variety of locations other than the brain. These tumors do not begin in brain tissue, but rather develop next to it, putting pressure on neural systems. A tumor might be located near the base of the brain or on the back of the skull. It might be growing in the eye sockets, in the nose and sinuses, or in the pituitary gland, among other places.

Structures of Skull Base

Most individuals are unaware of the skull base and its location until they are diagnosed with a tumor there. Simply described, the skull base refers to the cranium's base or floor, the section of the skull on which the brain sits. It is made up of five fused bones that separate the brain from the sinuses, ears, eyes, and other organs of the head.

The skull base is made up of the following bones:

• the ethmoid bone, which divides the nasal cavity from the brain.
• the sphenoid bone, which helps form the skull base, sides of the skull, and the sides of the eye sockets.
• the occipital bone, which forms the back and base of the skull.
• a pair of frontal bones, which make up the forehead and the upper part of the eye sockets.
• a pair of temporal bones, which form the lateral walls of the skull.

The base of the skull is a complicated area of the body. The skull base has a variety of holes that allow vital blood arteries and nerves to flow through. The spinal cord can pass through a hole in the occipital bone.

Skull Base Tumor Risk Factors

A risk factor is anything that raises your chances of developing a skull base tumor. Because skull base tumors are uncommon, determining risk factors is difficult.

Meningioma, certain sarcomas, and some sinonasal cancers have been linked to prior ionizing radiation exposure and certain occupational exposures. Wood dust, heavy metals, and a history of dealing with leather are all risk factors for developing various sinus and nose malignancies. Childhood Epstein-Barr virus exposure has been linked to some kinds of nasopharyngeal cancer.

Skull base tumors are sometimes associated with inherited genetic disorders. Our genetics specialists are part of the patient's care team in these circumstances. The following malignancies may be caused by genetic conditions:

• Acoustic neuromas, as well as other brain and spine tumors, may be caused by the genetic disorder neurofibromatosis type 2.
• Paragangliomas (also called glomus tumors or carotid body tumors) may be caused by a familial predisposition for other tumors.
• Pituitary tumors may be associated with multiple endocrine neoplasia 1 (MEN1) or family isolated pituitary adenoma (FIPA) which may be familial and predispose to other tumors.

Not everyone with risk factors gets skull base tumors. However, if you have risk factors, it’s a good idea to discuss them with your doctor.

Signs and Symptoms of Skull Base Tumor

As the tumor develops and exerts pressure on critical brain structures such as the pituitary gland, optic nerve, and carotid arteries, symptoms arise gradually.

The kind, location, and size of the tumor all influence the symptoms. Tumors affecting the skull base and nose, for example, might impair respiration and sense of smell. Some pituitary tumors can impair vision and swallowing.

In general, common symptoms of skull base tumors include:

• Headaches
• Difficulty breathing
• Altered sense of smell
• Blurred or double vision
• Trouble swallowing
• Hearing loss

Other symptoms may include:

• Loss of balance
• Nausea and vomiting
• Memory loss

Common Types of Skull Base Tumors

The term "skull base tumor" refers to the tumor's location. But not all skull base tumors are the same. Tumors come in a variety of forms. Furthermore, each form of skull base tumor develops slightly differently, which is an essential factor throughout therapy. The following are examples of skull base tumors:

Posterior skull base:

1. Acoustic neuroma:

It is a benign (noncancerous) tumor that is also known as vestibular schwannoma. It begins in the cells that encircle the hearing and balance nerve, which links your ear to your brain.

The majority of acoustic neuromas develop slowly. As growth occurs, the tumor presses against adjacent nerves, blood vessels, and the surface of the brain stem and cerebellum (the base of the brain). The pressure from a developing acoustic neuroma is what causes symptoms to develop.

• Where Acoustic Neuroma Develops?

Acoustic neuroma tumors arise in cells known as Schwann cells. These cells produce myelin, which is the substance that insulates and protects your body's nerves.

1. The vestibular nerve, which helps you maintain your balance, is where most acoustic neuromas originate. Hearing loss and balance problems are caused by tumor development.
2. Acoustic neuromas can start in the cochlear nerve, which transmits sound from your inner ear to your brain.

• Acoustic Neuroma Treatment:

After a diagnosis of an acoustic neuroma, the doctor will determine the best plan of action. The options include the following:

Surgery to remove the tumor: This is an extremely successful therapy for acoustic neuromas. Hearing loss caused by the tumor cannot be restored, however the residual hearing can be retained in certain circumstances. Surgical tumor excision can typically resolve balance issues, facial numbness, and other symptoms.

Stereotactic radiosurgery: This type of radiation treatment provides precisely focused radiation to the tumor while avoiding healthy tissue in the surrounding area. Radiation does not eliminate the tumor. Instead, the purpose is to halt or decrease growth. Radiation treatment is often not suggested for young patients or those with bigger malignancies.

Observation: This entails waiting and observing, and it may be an option for certain acoustic neuroma sufferers. Because auditory neuromas grow slowly, early intervention is not often required. The doctor may propose regular monitoring of the tumor using imaging such as MRI for individuals with extremely tiny tumors that do not produce any symptoms, elderly patients, and patients with major medical issues.

2. Craniopharyngioma:

It is a benign (non-cancerous) tumor that develops near the base of the brain, generally above the pituitary gland.It is uncertain what causes these tumors.

Craniopharyngiomas are most usually found in children under the age of 15 and individuals over the age of 50. There is no variation in prevalence based on gender or race.

• Craniopharyngioma Treatment:

Your neurosurgeon and endocrinologist (a specialist in hormone disorders) will collaborate to design the best treatment strategy for you. Treatment for a craniopharyngioma (or other brain tumor) may include surgical excision of the tumor by a craniotomy.

A conventional surgical method used to reach the skull base in order to treat tough tumors and aneurysms is the orbitozygomatic craniotomy. It is predicated on the idea that it is safer to remove superfluous bone than to modify the brain needlessly.

The craniopharyngioma is removed with this approach by making an incision in the scalp beneath the hairline and removing the bone that creates the shape of the orbit and cheek. Temporarily removing this bone helps the surgeon to access more difficult-to-reach parts of the brain while limiting catastrophic brain injury. At the completion of the treatment, the surgeon substitutes the bone.

Following surgery, your doctor may offer hormone replacement treatment and/or stereotactic radiosurgery.

3. Meningioma:

It is a slow-growing, noncancerous (benign) tumor that originates on the interior of the skull in the membranes that surround the brain. Meningiomas have a typically favorable prognosis. However, if meningioma recurs after therapy, it can become serious, if not fatal. Surgery and/or radiation are frequently used to treat grade I (benign) meningiomas. There is a chance that the tumor will return (recur), especially if it is not entirely eliminated. Tumors of grade II (atypical) and III (anaplastic or malignant) are more likely to return following therapy.

• Meningioma management:

neurosurgeons, neuro-oncologists, and radiation oncologists have extensive expertise treating meningioma at all stages. The vast majority of meningiomas are benign. If they are big or growing, they are either examined using MRIs or removed. The primary objective of treatment is to get rid of the tumor. If this is not feasible, or if the tumor is aggressive, our doctors will employ a combination of radiation and other therapies to reduce or stop its development.

Treatment approaches include:

1. MRI-guided microneurosurgery
2. Stereotactic radiosurgery
3. Image-guided radiation or re-irradiation
4. Proton radiotherapy
5. Brachytherapy
6. Targeted drug therapy and chemotherapy
7. Immunotherapy

4. Pituitary adenomas 

They are the most frequent form of pituitary tumor. A benign tumor that originates in glandular tissue is referred described as a "adenoma." Pituitary adenomas can develop into pituitary carcinomas, however this is exceedingly rare.

Adenomas can develop in locations other than the pituitary gland, such as the colon and the adrenal glands.

• Types of Pituitary Adenoma

Pituitary Microadenomas:

Microadenomas are tumors with a diameter of less than one centimeter. The majority of pituitary adenomas are microadenomas that seldom produce symptoms. Microadenomas are typically discovered during an MRI to test for another medical problem.

Pituitary Macroadenomas:

Macroadenomas are glandular tumors with a diameter more than one centimeter. Pituitary macroadenomas cause greater symptoms than microadenomas because they impose pressure on the brain and pituitary gland. People with macroadenomas, for example, are more prone to experience vision loss due to strain on the optic nerves.

Other vision problems that macroadenomas can cause include:

• narrowing field of vision (bitemporal hemianopsia)
• blurry vision
• colors seeming less bright
• double vision

• How are pituitary adenomas treated?

Pituitary adenomas are usually treated with surgery, medicine, radiation or a combination of these therapies.

Pituitary surgery: Endoscopic surgery may often remove the tumor by accessing the pituitary gland with extremely small equipment and a camera put via a small incision made through the nose and sinuses. This method is known as the transsphenoidal procedure. When this method is not possible, the doctor must open the skull to reach the pituitary and adenoma.

Medical treatment: Some pituitary adenomas can be treated with medicine that reduces the tumor and relieves symptoms.

Radiation treatment: It is the use of high-energy X-rays to destroy cancer cells and shrink tumors. Stereotactic radiosurgery is a type of radiation therapy that employs a high dosage of radiation focused precisely at the adenoma from many directions to keep the tumor from developing.

 In rare circumstances, the doctor may decide to utilize annual testing to ensure that the adenoma is not expanding while also monitoring the patient for any symptoms. This is possible with little tumors that may not cause substantial symptoms, as well as with patients who have other major medical concerns.

• Pituitary Adenomas Outlook

The prognosis is determined on the size and kind of adenoma. When the tumor is destroyed by therapy, most people with benign adenomas may resume their regular lives. Adenomas can return, requiring further therapy. Around 18% of patients with non-functioning adenomas and 25% of patients with prolactinomas, the most prevalent kind of hormone-releasing adenoma, may require further therapy at some time. In certain situations, adenoma treatment causes low hormone levels, which must be replaced with hormone replacement therapy.

5. Rathke cleft cysts 

Rathke cleft cysts (RCCs) are non-cancerous fluid-filled growths that form between pituitary gland sections near the base of the brain. They are congenital malformations, which means they appear when a fetus is developing in the womb. An RCC arises from a fragment of the developing fetus' Rathke pouch, which eventually forms a portion of the pituitary gland.

Rathke cleft cysts are uncommon. Furthermore, because they seldom produce symptoms or issues in children, they are infrequently diagnosed in children. They are more commonly discovered in adults on an MRI scan to detect another disease, or even after death if an autopsy is performed. Women are more prone than males to have this illness.

If Rathke cleft cysts become large enough, they can cause vision changes or various problems with the pituitary gland's normal processes.

• How are Rathke cleft cysts treated?

Rathke cleft cysts are treated based on their symptoms. Small RCCs that do not produce symptoms are not treated. Larger RCCs that cause symptoms may necessitate surgery, which may involve cyst draining and removal.

6. Chordoma

It is a slow-growing malignancy of the spine's tissue. Chordoma can occur at any point along the spine. It is most commonly discovered at the tailbone (referred to as a sacral tumor) or where the spine joins the skull (called a clival tumor). Chordoma is also known as a notochordal sarcoma.

Chordomas emerge from cells that were vital in the formation of the spine before to birth. These are known as notochord cells. Chordomomas can develop if the notochord cells do not dissolve after birth.

Chordomas develop at a glacial pace. Many people go years without seeing any changes in their body. When they do begin to have symptoms, it may take some time for the chordoma to be detected and diagnosed.

• How is chordoma treated?

Chordomas are surgically removed when feasible. Radiation therapy is occasionally performed in conjunction with surgery, or if surgery is not possible. Chordomas are difficult to cure because they develop on the spine, close to vital structures such as nerves and blood arteries. It might be difficult to remove the entire tumor from your spine without causing harm to other regions of your body.

Immunotherapy is being used in new studies to cure chordomas and identify alternative therapies. Immunotherapy is a cancer treatment that combats the disease by utilizing the body's immune system.

Anterior (Front) Skull Base:

These tumors develop in the region around the eye sockets and sinuses and include:

1. Sinus and nasal tumors

These uncommon tumors can be either malignant or noncancerous. Sinol nasal undifferentiated carcinoma (SNUC) and neuroendocrine carcinoma of the sinuses are two types of sinus and nasal cancers. Surgery, radiation, and chemotherapy are all possible treatments. 

Cancer of the nasal cavities or sinuses may be treated with surgery, radiation, or chemotherapy. If the tumor is tiny, it may frequently be removed using an endoscopic, minimally invasive procedure. An open surgical technique is typically necessary if a tumor has progressed into the face, eye, brain, nerves, or other critical tissues in the skull.

2. Olfactory neuroblastoma

The cribriform plate, a bone-deep in the skull between the eyes, is where this cancer grows. It has an impact on the nerve tissues that govern our sense of smell. Surgery may be used in treatment.

The primary therapy for nasal cavity cancer, such as olfactory neuroblastoma, is usually surgery to remove the tumor. This procedure is frequently used to remove a large swath of tissue surrounding the tumour as well, to assist guarantee that all of cancer has been eliminated. Wide local excision and medial maxillectomy are two frequent techniques. These are invasive treatments that may necessitate the rebuilding of a portion of the face, but they provide the highest long-term survival chances. Less invasive operations, such as endoscopic surgery with a thin flexible, lighted tube, may be possible in some cases.

Diagnosis of Skull Base Tumors

The diagnosis of skull base tumors begins with a physical exam that includes inquiries about your symptoms as well as your personal and family health history.

A neurological test will assess your vision, hearing, balance, coordination, reflexes, and thinking and memory abilities.

Brain imaging may involve the following:

1. Magnetic resonance imaging (MRI)
2. Computed tomography (CT or CAT scan)
3. A bone scan involves the injection of radioactive material into your bloodstream. The substance is absorbed by the tumor, and a picture is created using a computer and a specific camera. This allows your doctor to find the bone tumor and detect any cancer spread to other organs.
4. PET scans can identify changes in the growth of cells. A PET/CT scan, which is frequently used in combination with a CT scan, reveals tumor cells that have been injected with radioactive glucose and may be compared to normal areas of the brain.
5. Endoscopy, which uses a thin, lighted instrument to examine the nasal passages.

Conclusion

Skull base tumors can develop below the nose and eyes, around the ear, and along the brain's base.

Not all skull base tumors are malignant (malignant). Noncancerous (benign) skull base tumors, on the other hand, require investigation since they might produce unpleasant symptoms.

Depending on the size and location of the tumor, symptoms of skull base tumors may include: blindness or impaired vision, changes in taste and smell, swallowing or speaking difficulties, headaches, hearing loss, and ear ringing, dizziness and disorientation

To diagnose a skull base tumor, discussing your symptoms and completing a physical examination is a must. neurological examination to evaluate any impact on vital functions is also needed. Non-invasive tests such as CT scans and MRIs are used to confirm a diagnosis.

Depending on the location of the tumor, The excision of numerous brain tumors that may form in this region is the major reason for skull base surgery.