Spinal Axis Tumors

Spinal axis tumors

Definition

Spinal axis tumors are tumors that affect the spinal cord—the bundle of nerves that lies inside the backbone. Another term for spinal axis tumors is spinal cord tumors.

Description

Spinal axis tumors form on or near the spinal cord and produce pressure on the associated nerves and blood vessels. There are three types of spinal axis tumors: extradural, extramedullary intradural, and intramedullary.

Extradural spinal axis tumors

Extradural tumors are found outside the dura mater, the membrane that encases the spinal cord. Extradural tumors are wedged between the dura mater and the bone of the spine. Types of extradural tumors include chordomas, osteoblastomas, osteomas, and hemangiomas.

Extramedullary intradural spinal axis tumors

Extramedullary intradural tumors are found inside the dura mater but outside the nerves of the spinal cord itself. Types of extramedullary tumors include meningiomas and neurofibromas.

Intramedullary spinal axis tumors

Intramedullary tumors are found inside the nerves of the spinal cord. Types of intramedullary tumors include astrocytomas, ependymomas, and hemangioblastomas.

Benign vs. malignant

Spinal axis tumors are classified as either benign or malignant. The cells of malignant tumors are very different from normal cells, grow quickly, and usually spread easily to other parts of the body. Benign tumors have cells that are similar to normal cells, grow slowly, and tend to be localized. However, even benign tumors can cause significant problems when they grow within the confined space inside the backbone.

Demographics

Primary spinal axis tumors, or tumors that originate in the spinal axis itself, are extremely rare and represent only 0.5% of all diagnosed tumors. Malignant primary spinal axis tumors comprise about 65% of all spinal axis tumors. However, most spinal axis tumors result from metastasis , or spreading, of other types of cancer to the spinal axis. Other cancers that can spread to the spinal axis include head and neck cancer, thyroid cancer , skin cancer, prostate cancer , lung cancer, breast cancer , and others. The American Cancer Society estimates that brain and spinal cord cancers (primary only) represent approximately 1.4% of all cancers and 2.4% of all cancer-related deaths, but separate statistics for spinal cord cancers only are unavailable.

Half of all spinal axis tumors occur in the thoracic, or chest, region as opposed to the neck (cervical) or lower back (lumbar) region.

Spinal axis tumors occur with equal frequency in members of all races and ethnic groups. There does not appear to be any relationship between spinal axis tumors and any geographic region. Males and females are affected in equal numbers by spinal axis tumors.

Causes and symptoms

The cause, or causes, of primary spinal axis tumors are not known. The cause of metastatic spinal axis tumors is the originating cancer in another part of the body.

The symptoms of spinal axis tumors are the result of increased pressure on the nerves of the spine. These symptoms include:

• constant, severe, burning or aching pain
• numbness of the skin or decreased temperature sensation
• muscle weakness, wasting, or even paralysis
• problems with bladder and bowel control
• muscle spasticity or problems in walking normally

The location of the tumor determines where the symptoms are most noticeable. A tumor in the cervical region can cause symptoms in the neck or arms, while a tumor in the thoracic region may cause chest pain. A tumor in the lumbar region can result in observable symptoms in the back, bladder and bowel, and legs.

Diagnosis

The diagnosis of spinal axis tumors begins with a medical history and physical examination when the patient brings his or her symptoms to the doctor's attention. The diagnosis may be difficult to make due to the similarity of tumor symptoms to those caused by disc herniation or other spinal cord injuries.

If the doctor suspects a spinal axis tumor may be present, further diagnostic tests are ordered. These tests are performed by a neurological specialist. Imaging tests that may be ordered include:

• magnetic resonance imaging (MRI)
• computed tomography (CT)
• bone scan
• spinal tap and myelogram, a specialized x-ray technique

Treatment team

Treatment of any primary central nervous system tumor, including spinal axis tumors, is different from treating tumors in other parts of the body. Spinal cord surgery requires much more precision than most other surgeries. Also, the thoracic area, where the majority of spinal axis tumors are located, is highly sensitive to radiation. The most up-to-date treatment opportunities are available from experienced, multi-disciplinary medical professional teams made up of doctors, nurses, and technologists who specialize in cancer (oncology), neurosurgery, medical imaging, drug or radiation therapy , and anesthesiology.

Clinical staging, treatments, and prognosis

Malignant tumors of the spinal axis may spread (metastasize) to other parts of the central nervous system, but almost never spread to other parts of the body. As of mid-2001, there is no staging system for spinal axis tumors. The most important factors in determining prognosis for individuals with these tumors are the type of cell involved (eg. astrocyte, ependyma, etc.) and the grade of the tumor (an indicator of the aggressiveness of the tumor cells). Grade I tumors have cells that are not malignant and are nearly normal in appearance. Grade II tumors have cells that appear to be slightly abnormal. Grade III tumors have cells that are malignant and clearly abnormal. Grade IV tumors contain fast-spreading and abnormal cells. In general, the survival rate for some types of spinal cord tumors, such as extradural tumors and low-grade astrocytomas, is better than for other types, such as ependymomas.

The treatment of spinal axis tumors depends on the location of the tumor and the severity of the symptoms. Many spinal axis tumors can be treated by surgical removal of the tumor. Medical advances in surgical techniques, such as microsurgery and laser surgery, have greatly improved the success rate of spinal cord surgeries.

In some instances of spinal axis tumors, the tumor is inoperable. Patients with inoperable spinal axis tumors are generally treated with radiation therapies.

Other treatments may include the use of steroids to reduce swelling and pressure on the spinal cord, surgical decompression and fusion of the spine, and chemotherapy in selected cases. These may be the only treatments used if the spinal axis tumor is due to the metastasis of another primary cancer.

Prevention

Because the causes of spinal axis tumors are not known, there are no known preventative measures.

Special concerns

If left untreated, spinal axis tumors can cause loss of muscle function up to and including paralysis. This makes the proper diagnosis of spinal axis tumors important.

See Also Brain and central nervous system tumors; Chordoma; Astrocytoma; Ependymoma

Resources

BOOKS

Kaye, Andrew H., and Edward R. Laws, eds. Brain Tumors: An Encyclopedic Approach. New York: Churchill Living stone, 1995.

ORGANIZATIONS

The Brain Tumor Society. 124 Watertown Street, Suite 3-H, Watertown, MA 02472. (617) 924-9997. Fax: (617) 924-9998. <http://www.tbts.org/>.

National Brain Tumor Foundation. 785 Market Street, Suite 1600, San Francisco, CA 94103. (415) 284-0208. <http://www.braintumor.org/>.

OTHER

Brain and Spinal Cord Tumors—Hope Through Research. National Institute of Neurological Disorders and Stroke. <http://www.ninds.nih.gov/health_and_medical/pubs/brain_tumor_hope_through_research.htm>. (15 April 2001)

Spinal Cord Tumor Support. <http://www.spinalcordtumor.homestead.com>. (15 April 2001)

Paul A. Johnson, Ed.M.

KEY TERMS

Astrocytoma

—A tomor that begins in the brain or spinal cord in cells called astrocytes.

Chordoma

—A type of bone cancer.

Dura mater

—The tough membrane that encases the nerves of the spinal cord.

Ependymoma

—A tumor that begins in the tissue that lines the central canal of the spinal cord and the ventricles of the brain. About 85% of these tumors are benign.

Hemangioblastoma

—A tumor composed of capillaries and disorganized clumps of capillary cells or angioblasts.

Hemangioma

—A benign tumor consisting of a mass of blood vessels.

Meningioma

—A tumor that occurs in the meninges, the membranes that cover the brain and spinal cord. Meningiomas usually grow slowly and primarily affect adults.

Metastasic tumor

—A tumor that results from the spreading of one type of cancer to other parts of the body.

Neurofibroma

—A fibrous tumor of nerve tissue.

Osteoblastoma

—A benign tumor that most frequently occurs in the vertebrae, leg bones, or arm bones of children and young adults.

Osteoma

—A usually benign tumor of bone tissue.

Spinal cord

—The bundle of nerves that runs inside the backbone.

QUESTIONS TO ASK THE DOCTOR

• Which type of spinal axis tumor do I have?
• Is my tumor operable?