Tumors of The Spine

Structure of the Spine
The structure of the spine is complex and includes bone, muscle, intervertebral discs, ligaments, joints and nerves. Of these, the vertebrae and spinal cord are the most important for a better understanding of tumors that develop in these areas.

Vertebrae: The spinal column consists of 32-34 small bones, which are aligned one above the other, including the sacrum and coccyx. Most adults have 7 cervical vertebrae, 12 thoracic and 5 lumbar. The sacrum and coccyx are a total of 8-10 fused vertebrae. Each vertebra has a hole in its center. The aligned holes form a channel (spinal canal), which encloses and protects the spinal cord and the spinal nerve roots which branch off it.

Structure of the Spinal Cord

The spinal cord is a long column of nerve fibers that carries messages to and from the brain. It extends from the base of the skull down to the first lumbar vertebra, where it tapes to form the medullary cone. It continues until the sacral area and coccyx as thin connective tissue, the final filament. The length of the spinal cord is about 65 cm and its diameter varies with the height of the vertebral column and is about the thickness of the thumb. At its center is the central canal which is soaked in cerebrospinal fluid. The peripheral or spinal nerves exit from there. As the spinal cord reaches the height of the first lumbar vertebra, the lower nerves extend for a distance in the spinal canal, to exit, forming a structure resembling a horse's tail, the cauda equine.The spinal cord & cauda equine are surrounded by three layers of meninges (dura, arachnoid and pia), which form the meningeal sac. Cerebrospinal fluid circulates in the space between the arachnoid and dura mater (subdural space). Toothed link lateral denticulate ligaments extend throughout the length of this area. The space between the dura and the vertebrae is called the epidural space and contains fat and vessels. Structurally, the spinal cord consists of 2 parts: The inner layer has a butterfly shape is grey in color (gray matter) and contains the nerve cells and glia as well as blood vessels. The outer layer (white matter) there are nerve fibers (axons) that carry the sensory information, such as pain and sense of judgment, touch, pressure and temperature from the body to the brain and kinetic commands from the brain to the muscles, internal organs and glands.

Tumors of the Spine

Tumors of the spine are relatively rare. They can be either primary (from bone cells) or secondary (metastases from other primary cancer sites). They grow at different rates. In general, malignant tumors grow rapidly, while benign tumors can grow slowly, and often grow for years before causing any symptoms.

Symptoms

The most common initial symptom in patients with such tumors is pain. Back pain is common and not a specific symptom of any disease or physical condition. The pain may be worse at night or on awakening. It can also spread beyond the spine to the hips, legs, or arms and usually worsens over time, despite receiving analgesic treatment. Depending on the location and type of tumor, other symptoms develop, resulting in displacement or in breach of neural structures, vertebrae, blood vessels and intervertebral disc, comprising:

• palsy (muscular weakness) or paralysis (complete inability -disability) that may occur in varying degrees and in different parts of the body, depending on the anatomical location of the tumor
• Difficulty in walking, which may lead to falls
• Difficult to perform subtle movements
• Reduced sensitivity to pain, heat and cold
• Loss of bladder control and / or bowel
• Distortion of the spine

Diagnosis of Spinal tumors

Spinal tumors can sometimes not be detected immediately as they are rare and because their symptoms resemble those of more common diseases. It is extremely important for your doctor be aware of your full medical history and if there is suspicion to schedule diagnostic tests to be done, which are able to confirm the diagnosis and determine the location of the tumor. MRI is the examination of choice, as it is the only test that produces highest resolution images of all anatomical structures of the spine and spinal cord. Computed tomography is sometimes necessary to determine the degree of infiltration of bony structures (vertebrae), and to plan surgery. Often specialized lumbar puncture and CSF examination is required, particularly if demyelinating disease, or myelitis is suspected. Bone scintigraphy is able to determine dispersion, usually metastatic tumors. Simple radiographic examination is the most widely used and easily performed initial diagnostic test. Based on the direct and indirect evidence that are highlighted further neuroimaging tests are scheduled. In some cases CT guided biopsy is proposed performed under isolated-local anesthesia, as this is the only diagnostic test that provides histological identification of tumors, especially tumors of the vertebrae. This is not applicable to intramedullary tumors.


Treatment of Spine tumors

Depending on neuroimaging characteristics of the tumor and histological diagnosis of the biopsy taken from the tumor, further treatment is decided either surgical or radiation and radiosurgery treatment or chemotherapy (usually in metastases¬)
In ideal cases, the treatment goal of a spinal and spinal cord tumor is the total resection of the tumor and restoration of spine stability while protecting the functionality of sensitive nerve structures. Any intervention however carries the risk of permanent neurological damage. To select the most appropriate treatment method the neurological state, age, general health status of the patient, the type and location of the tumor and whether it is primary or secondary (metastatic) tumor are taken into consideration.
Primary spinal cord tumors in adults are mostly benign and develop slowly. They account for 15% of the neoplasms of the CNS. 2/3 of them are extramedullary and usually benign. The more common histological types of tumors are tumors of nerve sheath, ependymomas meningioma, astrocytoma, Filum terminale ependymomas and hemangioblastomas. Treatment options for most tumors include:

Monitoring:

The common signs and symptoms of a tumor of the spinal cord show a typically slowly growing mass and include pain in the back, neck, arm, atrophy or paresis or plegia and corticospinal tract lesions. If the lesion involves the myeloid tergum, the parasympathetic innervation of the bowel and bladder and genital organs are affected. If the lesion is in the cauda equine it can cause selective deduction in the function of a nerve root and a subtle dermatomal correlation of pain with the root.

Often the tumors are diagnosed before they cause symptoms, in random tests done for other reasons. In certain cases, small apparently benign tumors that do not significantly displace sensitive nerve structures, or intramedullary with a high intraoperative risk. Accessible lesions that cause only mild symptoms treated only with monitoring especially in the case of the elderly and in cases where surgery or radiation may cause irreversible damage to neural structures. Monitoring is normally done with MRI at regular intervals, 6-12 month or if symptoms get worse.


Surgical Treatment: This is often the first step in treating tumors that can be removed with an acceptable risk of possible postoperative neurological deterioration. The newer techniques, especially intraoperative neuromonitoring , the use of tumor resection devices which function with ultrasound, microscopes, endoscopes, and micro surgical instruments now allow neurosurgeons to access and completely remove tumors that were previously inoperable. However, even with the implementation of all new technologies, it is not always possible to remove all tumors.

Surgical removal is the best option for many intramedullary and intradural -extramedullary tumors, but tumors like widespread ependymomas, may be impossible to remove completely from the spinal cord or the nerves of the cauda equine. Today we are able to perform surgery with more precision using neuromonitoring and neuronavigation. Neuromonitoring allows us to control intraoperative stimulation and recording from the nerves of the spinal column to minimize the possibility of intraoperative injury to a nerve or the spinal cord itself depending on the level of surgical access.

Neuronavigation allows accurate preoperative localization of the tumor and intraoperative determination of surgical margins in order not to influence the healthy surrounding neural structures. Most benign tumors are usually removed completely, which is not always achieved in metastatic or invasive intramedullary tumors.

Especially for metastatic tumors, the treatment of choice is radiotherapy and only in case of progressive neurological deterioration or instability of the spine surgery is recommended. Rehabilitation after surgery can take weeks or months, during which, often, symptoms are more pronounced, compared with the preoperative state.

Radiotherapy: Can be used after surgery to control the residual disease or to prevent recurrence, or to deal with inoperable tumors. It is treatment of choice for metastatic tumors and is often used as emergency treatment. Radiation can also be used to relieve pain when there is no possibility of cure. Side effects of radiation, such as dizziness and nausea adequately treated with medication. In radiotherapy of the spine targeting techniques are applied and segmentation of the dose over several sessions in order to prevent damage to surrounding tissue and improve the effectiveness of treatment.

Chemotherapy: Chemotherapy has not proved beneficial for most spinal and spinal cord tumors. However, there are exceptions. In some cases chemotherapy is advisable, but always in combination with surgery and / or radiotherapy. It is usually used in metastatic tumors.