A spinal tumor is an abnormal mass of tissue found within or surrounding the spinal cord and/or the spinal column. These tumor cells grow, multiplying uncontrollably. They appear to be unchecked by regulating mechanisms for the control of normal cells. Spinal tumors may be non-cancerous or cancerous, referred to as benign and malignant, respectively. Primary tumors originate in the spine or spinal cord, while metastatic or secondary tumors occur as cancer spreads from another site to the spine.
Spinal tumors are referred to in two ways.
- Through their region in the spine (cervical, thoracic, lumbar and sacrum)
- Through their location within the spine.
- Intradural-extramedullary: Inside the thin covering of the spinal cord (known as the dura), but not located within the spinal cord with 40% occurrence frequency. The most commonly occurring intradural-extramedullary tumor develops within the arachnoid membrane, or meningiomas; in the nerve roots extending out from the spinal cord (schwannomas and neurofibromas); or at the base of the spinal cord (filum terminale ependymomas). Although meningiomas are usually benign, they may be difficult to remove and eventually recur. Nerve root tumors are also usually benign (harmless), but neurofibromas may grow malignant. Ependymomas near the spinal cord’s end may be large, and the delicate nature of that region’s fine neural structures may cause removal to be difficult.
- Intramedullary: Located inside the spinal cord, they often originate from glial or ependymal cells. These are found throughout the spinal cord’s interstitium with the frequency of tumor occurrence in this location is about 5%. Astrocytomas and ependymomas are the two most commonly occuring types. Astrocytomas are more commonly occuring in the thoracic region, with the cervical being the next most common. Ependymomas are most commonly occuring in the filum (bottom region of the spinal cord), with the cervical being the next most common. They are usually benign (in comparison to intracranial), but may be difficult to take away. Intramedullary lipomas are rare congenital tumors most commonly occurring located in the cervicothoracic spinal cord.
- Extradural: Outside the dura (the thin covering that surrounds the spinal cord). Frequency of occurrence in this location vs the aforementioned ones is about 55%. These lesions are often attributed to metastatic cancer or less commonly occurring schwannomas derived from the cells covering the nerve roots. At times, 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 commonly occuring site for bone metastasis. Approximately, at least 30% and as high as 70% of patients who have cancer will experience the spread of cancer to their spine. The most commonly occuring 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 prostrate, lung, and breast. In comparison to other cancers, lung cancer often metastasizes to the bone in men, and breast cancer is the most commonly occuring in women. Other cancers that spread to the spine include multiple melanoma, myeloma, lymphoma, and sarcoma, along with cancers of the gastrointestinal tract, kidney, and thyroid. Prompt diagnosis and identification of the primary malignancy is essential to overall treatment. Numerous factors may affect outcome, including the number of lesions, the nature of the primary cancer, the presence of distant non-skeletal metastases and the presence and/or severity of spinal-cord compression.
PEDIATRIC SPINAL TUMORS
- Mesenchymal Chondrosarcoma
- Giant-Cell Tumor Of Bone
- Fibrous Dysplasia
- Osteoid Osteoma
- Ewing Sarcoma
- Eosinophilic Granuloma
- Aneurysmal Bone Cyst
Unlike adults, children have not fully achieved skeletal growth, which doctors must take into account when considering treatment. Other factors to consider are spinal stability, surgical versus nonsurgical interventions, as well as preservation of neurological function.
INCIDENCE AND PREVALENCE
Intracranial (brain) tumors account for 85-90% of primary central nervous system tumors, or CNS tumors. Primary tumors arising from the spinal cord, spinal nerve roots, and dura are rare in comparison to CNS tumors from the brain. Overall prevalence is estimated at one spinal tumor for every four intracranial lesions.
For tumors of the spine, there are different incidences of tumor types, which are related to the neural/dural elements vs the surrounding vertebral bony support. Intramedullary tumors are rare in comparison to metastatic tumors of the spine. Vertebral hemangiomas are the most commonly occuring benign bony primary spinal tumor. Spinal epidural metastases are the most commonly occurring type of spinal tumor. They occur in up to 10% of cancer patients. Metastatic spinal tumors often take hold in the bony spine and then grow to cause compression of the neural elements (spinal cord and nerve roots).
The cause of most primary spinal tumors is unknown. Some may be attributed to exposure to cancer-causing agents. Spinal cord lymphomas (cancers that affect lymphocytes) are more commonly occurring in people with compromised immune systems. There appears to be a higher incidence of spinal tumors in particular families, so a genetic component is most likely present.
In a small number of cases, primary tumors may result from presence of these two genetic diseases:
- Neurofibromatosis 2: In this hereditary (genetic) disorder, benign tumors may develop in the arachnoid layer of the spinal cord or in the supporting glial cells. Nevertheless, the more commonly occurring tumors associated with this disorder affect the nerves related to hearing and may inevitably lead to loss of hearing in one or both ears.
- Von Hippel-Lindau disease: This rare, multi-system disorder is associated with benign blood vessel tumors (hemangioblastomas) in the brain, retina, and spinal cord, along with other types of tumors in the kidneys or adrenal glands.
Non-mechanical back pain, especially in the middle or lower regions of the back, is the most frequently occurring symptom of benign and malignant spinal tumors. This back pain is not specifically attributed to injury, stress, or physical activity. Nevertheless, the pain may increase with activity and may worsen at night when lying down. Pain may also spread beyond the back to the hips, legs, feet or arms and may worsen over time, even if it is treated by conservative, nonsurgical methods that may usually help alleviate back pain attributed to mechanical causes. Depending on the location and type of tumor, other signs and symptoms may develop, especially as a tumor grows and compresses the spinal cord, the nerve roots, blood vessels, or bones of the spine.
Additional symptoms may include the following:
- Loss of bowel or bladder function
- Paralysis that may occur in varying degrees and in different parts of the body, depending on which nerves are compressed
- Loss of sensation or muscle weakness in the legs, arms or chest
- Stiff neck or back
- Scoliosis or other spinal deformity resulting from a large and/or destructive tumor
- Pain and/or neurologic symptoms (such as tingling) increase with Valsalva maneuver
- Difficulty walking, which may cause falls
- Decreased sensitivity to pain, heat and cold
TESTING & DIAGNOSIS
A thorough medical examination with emphasis on back pain and neurological deficits is the initial step in diagnosing a spinal tumor. Radiological tests are required for an accurate and positive diagnosis.
- Computed tomography scan (CT or CAT scan)
- Magnetic resonance imaging (MRI)
- Bone Scan
Radiology studies noted above provide imaging findings that suggest the most likely tumor type. Nevertheless, a biopsy may be required if diagnosis is unclear or if concern for malignancy vs benign tumor type. If the tumor is malignant, a biopsy also helps to determine the cancer's type, subsequently determining 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, along with a CT scan of the lungs and abdomen for staging purposes. To confirm diagnosis, a doctor compares laboratory test results and findings from the aforementioned scans to the patient's symptoms.
Treatment decision-making is usually multidisciplinary, incorporating the expertise of spinal surgeons, medical oncologists, radiation oncologists, and other medical specialists. The selection of both surgical and non-surgical treatments is therefore made with the various aspects of the patient’s overall health and goals of care in mind.
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 monitored with MRIs. Some tumors respond well to chemotherapy, while others respond to radiation therapy. Nevertheless, 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.
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 mostly palliative, using the goal of restoring or preserving neurological function, stabilizing the spine, and alleviating pain. Usually, 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.
In terms of cases when surgical resection is possible, preoperative embolization may be utilized 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. At the site, 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 may usually 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 utilized for tumors in the posterior aspect of the spinal column or to expose tumors inside the dura. Multiple levels may be decompressed, and multilevel segmental fixation may be performed if needed. The anterior (front) approach is excellent for tumors in the front of the spine. This approach also allows for the reconstruction of defects prompted by removal of the vertebral bodies. This approach also allows placement of short-segment fixation devices. Thoracic and lumbar spinal tumors that affect the anterior and posterior vertebral columns may 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.
Outcome depends on the patient's age and general health, as well as whether the spinal tumor is benign or malignant, or primary or metastatic. With primary tumors, the goal is to remove the tumor completely, leading to the potential cure of the malignancy. In certain primary tumor types (particularly ones arising inside the spinal cord-intramedullary) complete resection is not possible without significant neural damage. In the case of metastatic tumors, the goal is almost always palliative, with treatment aimed at providing a patient with improved quality of life and possibly prolonged life expectancy. Treatment advances related to spine stereotactic body radiotherapy (SBRT), combined with spinal epidural decompression, have the opportunity to provide greater control of metastatic disease of the spine in certain patients.
Surgery in adults for a variety of spinal tumor types has been associated with a risk for major complications (at most 14%). The most commonly occuring complications are surgical site infection, systemic infections, and deep venous thrombosis. Please note that postoperative complications are more commonly occurring in patients who have significant comorbidities (such as steroid use).