A brain tumor is a mass of cells that grows over time and expands inside the brain. This expansion causes two general types of symptoms:
- Increased pressure inside the head (intracranial pressure)
- Disrupted brain function
The increased intracranial pressure can result from the growing tumor itself, swelling associated with metastatic tumors, or hydrocephalus (a swelling caused by the accumulation of too much cerebrospinal fluid) obstructing the normal flow of cerebral spinal fluid.
Symptoms of Brain Tumors
Common symptoms patients notice include
- Nausea and vomiting
- General confusion
A new pattern or type of headache is the first noticeable symptom for about 20 percent of all people with brain tumors. Eventually, headaches will occur in more than 60 percent to 70 percent of all patients at some point in the course of their illness.
The headache often is on the same side of the tumor but may be located anywhere on the head. Many headaches associated with brain tumors tend to be located on the frontal areas of the head (forehead/top of head). This happens not because the tumor is there, but rather because that is where the pain is referred (referred pain is pain that is felt somewhere different from where it originates).
Headaches caused by brain tumors are usually non-throbbing and worse in the morning after lying flat all night, because pressure in the brain increases when the head is down. They may be worse with exertion. Most patients describe nausea and vomiting with the headache. If the tumor is obstructing the ventricles, the structures that contain the cerebrospinal fluid, the headache may get worse when a person changes position.
These tumors occur in the glial cells, which help support and protect critical areas of the brain. Gliomas are the most common type of brain tumor in adults, responsible for about 42 percent of all adult brain tumors. Brain stem gliomas that are high-grade or spread widely throughout the brain stem are difficult to treat successfully. To prevent damage to healthy brain tissue, brain stem glioma is usually diagnosed without a biopsy. Gliomas are further characterized by the types of cells they affect:
A seizure is a sudden, brief attack of uncontrolled motor activity or altered consciousness. Seizures occur in approximately 35 percent of all brain tumor patients. The probability of having a seizure depends on the location of the tumor, as some parts of the brain are more prone to seizure activity than others. Some seizures may be partial and involve only a single site in the brain. Others can affect the whole brain and result in loss of consciousness.
Nausea and Vomiting
When a person develops a new pattern of headaches in the morning coupled with vomiting, they should be further evaluated for the presence of a brain tumor. Even if this particular pattern doesn't develop, many people with brain tumors eventually develop chronic nausea and loss of appetite, which are presumably associated with the increased intracranial pressure (pressure within the skull compartment).
Change in Cognitive Status
Patients with tumors often develop changes in their cognitive abilities. These include difficulties remembering things, changes in personality or mood, lack of initiative, and poor judgment.
Depending on where the tumor is located, a person may have reading, writing or speaking difficulties. It may be very difficult for some folks to engage in abstract reasoning, and some people may not be able to make decisions. Many people with brain tumors suffer from sleep disorders and restlessness and are unable to concentrate.
When the function of the brain is disrupted by localized problems associated with a tumor, symptoms include:
- Speech and language problems
- Visual problems
- General weakness
The particular symptom often reflects where in the brain the tumor is located.
The various symptoms of neurological dysfunction occur no matter how slowly or quickly the tumor grows. In slow-growing tumors, however, the brain can sometimes accommodate for the growth of the tumor, and the symptoms may be less pronounced. When the tumor grows rapidly, the symptoms may occur very suddenly and intensely.
Diagnosis of Brain Tumors
Magnetic resonance imaging (MRI) has established itself as an important clinical tool in the diagnosis of central nervous system diseases. While MRI indications in the body are expanding, evaluation of central nervous system diseases remains the most common application of MRI today.
The complete imaging evaluation of patients with central nervous system diseases includes:
- Determination of tumor size
A biopsy is usually required to definitely diagnose a brain tumor. The physician needs to know the tumor type and grade to plan the proper treatment. A biopsy involves removing a piece of the tumor for viewing under a microscope. This is critical for an accurate diagnosis.
Types of Central Nervous System Tumors
There are many different types of brain tumors, based on what cells are affected and how they appear under a microscope. Tumors can be classified into four general categories: gliomas, meningiomas, acoustic neuroma and medulloblastoma.
Gliomas occur in the glial cells, which help support and protect critical areas of the brain. Gliomas are the most common type of brain tumor in adults, responsible for about 42 percent of all adult brain tumors. Brain stem gliomas that are high-grade or spread widely throughout the brain stem are difficult to treat successfully. To prevent damage to healthy brain tissue, brain stem glioma is usually diagnosed without a biopsy.
Gliomas are further characterized by the types of cells they affect:
- Astrocytes: These are star-shaped cells that protect neurons. Tumors of these cells can spread from the primary site to other areas of the brain, but they rarely spread outside the central nervous system. Astrocytomas are graded from I to IV depending on the speed of progression:
- Grade I (pilocytic astrocytoma): Slow growing, with little tendency to infiltrate surrounding brain tissue. Most common in children and adolescents.
- Grade II (diffuse astrocytoma): Fairly slow-growing, with some tendency to infiltrate surrounding brain tissue. Mostly seen in young adults.
- Grade III (anaplastic/malignant astrocytoma): These tumors grow rather quickly and infiltrate surrounding brain tissue.
- Grade IV (glioblastoma multiforme, GBM): An extremely aggressive and lethal form of brain cancer. Unfortunately, it is the most common form of brain tumor in adults, accounting for 67 percent of all astrocytomas.
- Oligodendroglioma: Oligodendrocytes are cells that make myelin, a fatty substance that forms a protective sheath around nerve cells. Oligodendrogliomas, which make up 4 percent of brain tumors, mostly affect people age 45 and older. Some subtypes of this tumor are particularly sensitive to treatment with radiation therapy and chemotherapy. Half of patients with oligodendrogliomas are still alive after five years.
- Ependymoma: These tumors affect ependymal cells, which line the pathways that carry cerebrospinal fluid throughout the brain and spinal cord. Ependymomas are rare. They make up about 2 percent of all brain tumors, but they are the most common brain tumor in children. They generally don't affect healthy brain tissue and don't spread beyond the ependyma. Although these tumors respond well to surgery, particularly those on the spine, ependymomas cannot always be completely removed. The five-year survival rate for patients over age 45 approaches 70 percent.
Meningiomas affect the meninges, the tissue that forms the protective outer covering of the brain and spine. One-quarter of all brain and spinal tumors are meningiomas, and up to 85 percent of them are benign. Meningiomas can occur at any age, but the incidence increases significantly in people over age 65. Women are twice as likely as men to have meningiomas. They generally grow very slowly and often don't produce any symptoms. In fact, many meningiomas are discovered by accident. Meningiomas can be successfully treated with surgery, but some patients, particularly the elderly, may be candidates for watchful waiting to monitor the disease.
Acoustic neuroma/schwannomas: Schwann cells are found in the sheath that covers nerve cells. Vestibular schwannomas, also known as acoustic neuromas, arise from the eighth cranial nerve, which is responsible for hearing. Specific symptoms of vestibular schwannoma include buzzing or ringing in the ears, one-sided hearing loss and/or balance problems. Schwannomas are typically benign and respond well to surgery.
Medulloblastoma is a common brain tumor in children, usually diagnosed before the age of 10. These tumors occur in the cerebellum, which has a crucial role in coordinating muscular movements. Some experts believe that medulloblastomas arise from fetal cells that remain in the cerebellum after birth. Tumors grow quickly and can invade neighboring portions of the brain, as well as spreading outside the central nervous system. Medulloblastoma is slightly more common in boys.