A spinal tumor is an abnormal mass of tissue within or surrounding the spinal cord and/or spinal column. These cells grow and multiply uncontrollably, seemingly unchecked by the mechanisms that control normal cells. Spinal tumors can be benign (non-cancerous) or malignant (cancerous). Primary tumors originate in the spine or spinal cord, and metastatic or secondary tumors result from cancer spreading from another site to the spine.
Spine tumors may arise from any of the structures of the spine or the spinal column. They may arise in the cervical (neck), thoracic (mid-back), or lumbosacral (low back) regions. They may originate in the spinal cord itself, the spinal roots, the dural sac which surrounds the spinal cord, or the vertebrae (bones). They may be primary—originating from the spine or spinal cord—or metastatic, originating elsewhere (ie, lung, breast, etc).
Tumors of the brain and spinal cord are abnormal growths of tissue found inside the skull or the bony spinal column. The brain and spinal cord are the primary components of the central nervous system (CNS). Benign tumors are noncancerous, and malignant tumors are cancerous. The CNS is housed within rigid, bony quarters (i.e., the skull and spinal column), so any abnormal growth, whether benign or malignant, can place pressure on sensitive tissues and impair function. Tumors that originate in the brain or spinal cord are called primary tumors. Most primary tumors are caused by out-of-control growth among cells that surround and support neurons, specific genetic diseases (such as neurofibromatosis type 1 and tuberous sclerosis), or exposure to radiation or cancer-causing chemicals. Metastatic, or secondary, tumors in the CNS are caused by cancer cells that break away from a primary tumor located in another region of the body. Tumors can place pressure on sensitive tissues and impair function. Symptoms of brain tumors include headaches, seizures, nausea and vomiting, poor vision or hearing, changes in behavior, unclear thinking, and unsteadiness. Spinal cord tumor symptoms include pain, numbness, and paralysis. Diagnosis is made after a neurological examination, special imaging techniques (computed tomography, and magnetic resonance imaging, positron emission tomography), laboratory tests, and a biopsy (in which a sample of tissue is taken from a suspected tumor and examined).
Types of Spinal Tumor
By the region of the spine in which they occur. These basic areas are cervical, thoracic, lumbar, and sacrum. By their location within the spine.
- Intradural-extramedullary – The tumor is located inside the thin covering of the spinal cord (the dura), but outside the actual spinal cord. The frequency of occurrence in this location is 40%. The most common of these types of tumors develop in the spinal cord’s arachnoid membrane (meningiomas), in the nerve roots that extend out from the spinal cord (schwannomas and neurofibromas), or at the spinal cord base (filum terminale ependymomas). Although meningiomas are often benign, they can be difficult to remove and may recur. Nerve root tumors are also generally benign, although neurofibromas may become malignant over time. Ependymomas at the end of the spinal cord can be large, and the delicate nature of fine neural structures in that area may make removal difficult.
- Intramedullary – These tumors grow inside the spinal cord. They typically derive from glial or ependymal cells (a type of glial cell) that are found throughout the interstitium of the spinal cord. The frequency of occurrence in this location is approximately 5%. Astrocytomas and ependymomas are the two most common types. Astrocytomas are more common in the thoracic region followed by the cervical. Ependymomas are most common in the filum (bottom region of the spinal cord), followed by the cervical region. They are often benign (compared to intracranial), but can be difficult to remove. Intramedullary lipomas are rare congenital tumors most commonly located in the cervicothoracic spinal cord.
- Extradural – The tumor is located outside the dura, which is the thin covering surrounding the spinal cord. The frequency of occurrence in this location vs the ones above is approximately 55%. These lesions are typically attributed to metastatic cancer or less commonly schwannomas derived from the cells covering the nerve roots. Occasionally, an extradural tumor extends through the intervertebral foramina, lying partially within and partially outside of the spinal canal.
The bony spinal column is the most common site for bone metastasis. Estimates indicate that at least 30% and as high as 70% of patients with cancer will experience the spread of cancer to their spine. The most common primary spine tumor (originated in the bony spine) is vertebral hemangiomas. These are benign lesions and rarely cause symptoms such as pain.
Common primary cancers that spread to the spine are lung, breast, and prostate. Lung cancer is the most common cancer to metastasize to the bone in men, and breast cancer is the most common in women. Other cancers that spread to the spine include multiple myeloma, lymphoma, melanoma, and sarcoma, as well as cancers of the gastrointestinal tract, kidney, and thyroid. Prompt diagnosis and identification of the primary malignancy are crucial to overall treatment. Numerous factors can affect outcomes, including the nature of primary cancer, the number of lesions, the presence of distant non-skeletal metastases, and the presence and/or severity of spinal cord compression.
Non-mechanical back pain, especially in the middle or lower back, is the most frequent symptom of both benign and malignant spinal tumors. This back pain is not specifically attributed to injury, stress or physical activity. However, the pain may increase with activity and can be worse at night when lying down. Pain may spread beyond the back to the hips, legs, feet or arms and may worsen over time — even when treated by conservative, nonsurgical methods that can often help alleviate back pain attributed to mechanical causes. Depending on the location and type of tumor, other signs and symptoms can develop, especially as a tumor grows and compresses on the spinal cord, the nerve roots, blood vessels or bones of the spine.
Additional symptoms can include the following:
- Loss of sensation or muscle weakness in the legs, arms, or chest
- Stiff neck or back
- Pain and/or neurologic symptoms (such as tingling) increase with the Valsalva maneuver
- Difficulty walking, which may cause falls
- Decreased sensitivity to pain, heat, and cold
- Loss of bowel or bladder function
- Paralysis may occur in varying degrees and in different parts of the body, depending on which nerves are compressed
- Scoliosis or other spinal deformity resulting from a large and/or destructive tumor
A thorough medical examination with emphasis on back pain and neurological deficits is the first step to diagnosing a spinal tumor. Radiological tests are required for an accurate and positive diagnosis.
- X-ray – Application of radiation to produce a film or picture of a part of the body can show the structure of the vertebrae and the outline of the joints. X-rays of the spine are obtained to search for other potential causes of pain, i.e. tumors, infections, fractures, etc. X-rays, however, are not very reliable in diagnosing tumors.
- Computed tomography scan (CT or CAT scan) – A diagnostic image created after a computer reads X-rays, a CT/CAT scan can show the shape and size of the spinal canal, its contents, and the structures around it. It also is very good at visualizing bony structures.
- Magnetic resonance imaging (MRI) – A diagnostic test that produces three-dimensional images of body structures using powerful magnets and computer technology. An MRI can show the spinal cord, nerve roots, and surrounding areas, as well as enlargement, degeneration, and tumors.
- Bone Scan – A diagnostic test using Technetium-99. Helpful as an adjunct for identification of bone tumors (such as primary bone tumors of the spine), infection, and diseases involving abnormal bone metabolism.
Radiology studies noted above provide imaging findings that suggest the most likely tumor type. In some cases, however, a biopsy may be needed if the diagnosis is unclear or if concern for malignancy vs benign tumor type. If the tumor is malignant, a biopsy also helps determine cancer’s type, which subsequently determines treatment options.
Staging classifies neoplasms (abnormal tissue) according to the extent of the tumor, assessing bony, soft tissue, and spinal canal involvement. A doctor may order a whole-body scan utilizing nuclear technology, as well as a CT scan of the lungs and abdomen for staging purposes. To confirm the diagnosis, a doctor compares laboratory test results and findings from the aforementioned scans to the patient’s symptoms.
Treatment decision-making is often multidisciplinary, incorporating the expertise of spinal surgeons, medical oncologists, radiation oncologists, and other medical specialists. The selection of treatments including both surgical and non-surgical is therefore made keeping in mind the various aspects of the patient’s overall health and goals of care.
Non-Surgical Treatments
Nonsurgical treatment options include observation, chemotherapy, and radiation therapy. Tumors that are asymptomatic or mildly symptomatic and do not appear to be changing or progressing may be observed and monitored with regular MRIs. Some tumors respond well to chemotherapy and others to radiation therapy. However, there are specific types of metastatic tumors that are inherently radioresistant (i.e. gastrointestinal tract and kidney): in those cases, surgery may be the only viable treatment option.
Surgery
Indications for surgery vary depending on the type of tumor. Primary (non-metastatic) spinal tumors may be removed through complete en bloc resection for a possible cure. In patients with metastatic tumors, treatment is primarily palliative, with the goal of restoring or preserving neurological function, stabilizing the spine, and alleviating pain. Generally, surgery is only considered as an option for patients with metastases when they are expected to live 3 – 4 months or longer, and the tumor is resistant to radiation or chemotherapy. Indications for surgery include intractable pain, spinal cord compression, and the need for stabilization of pathological fractures.
For cases in which surgical resection is possible, preoperative embolization may be used to enable an easier resection. This procedure involves the insertion of a catheter or tube through an artery in the groin. The catheter is guided up through the blood vessels to the site of the tumor, where it delivers a glue-like liquid embolic agent that blocks the vessels that feed the tumor. When the blood vessels that feed the tumor are blocked off, bleeding can often be controlled better during surgery, helping to decrease surgical risks.
If surgery is considered, the approach to the tumor is determined by the tumor’s location within the spinal canal. The posterior (back) approach allows for the identification of the dura and exposure of the nerve roots. This approach is commonly used for tumors in the posterior aspect of the spinal column or to expose tumors inside the dura. Multiple levels can be decompressed, and multilevel segmental fixation can be performed if necessary. The anterior (front) approach is excellent for tumors in the front of the spine. This approach also allows for the reconstruction of defects caused by the removal of the vertebral bodies. This approach also allows the placement of short-segment fixation devices. Thoracic and lumbar spinal tumors that affect both the anterior and posterior vertebral columns can be a challenge to resect completely. Not infrequently, a posterior (back) approach followed by a separately staged anterior (front) approach has been utilized surgically to treat these complex lesions.
References
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