Surgery on the spine may be carried out for benign (non-cancerous) and malignant (cancerous) disease of the spine and its contents. However, most surgery on the spine is for degenerative disease including surgery for ruptured (herniated) disk (see Cervical Discectomy, Lumbar Discectomy, Lumbar Spinal Fusion, Cervical Laminectomy, Decompressive Lumbar Laminectomy), The first successful operation for a spinal tumor was in 1881 by Macewen on a patient who was completely paralyzed from the chest down. Removal of the tumor eventually led to a complete recovery.

Anatomy

• The normal spine is composed of building blocks called vertebrae
• There are seven cervical (neck), twelve thoracic (chest) and five lumbar (low back) vertebrae (Figure 1)

Figure 1 - The spine is composed of 5 cervical, 12 thoracic and 5 lumbar vertebrae.

• At the upper end of the cervical spine sits the head
• Each vertebra is constructed of a body, lamina, and pedicles, which surround an opening, the spinal canal. On each side of a vertebra lie the facets, the portion of the vertebra that forms the joints between two vertebrae (Figure 2)

Figure 2 - Cross-section through a cervical vertebra. All of the vertebrae have a similar basic structure.

• Through the spinal canal passes the spinal cord. Nerve roots exit the spinal cord at each vertebral level and leave the spine through holes (foramina) formed by two adjacent vertebrae. The nerve roots eventually form into nerves that go to the arms, torso and legs. The long nerve roots at the end of the spinal cord that go to form the nerves to the legs are together called the cauda equina (See Decompressive Lumbar Laminectomy)
• The spinal cord and roots float in fluid (cerebrospinal fluid, CSF) and are contained within a fibrous sac called the dura. The subarachnoid space lies between the spinal cord and dura and contains CSF. In the center of the spinal cord is a thin tube called the central canal, which is lined by a single layer of ependymal cells
• The spinal cord is made up of many nerve tracts that run the length of the cord and carry electrical impulses from the brain to the nerve roots at every level and from the nerve roots to the brain. The major tracts that control movement are in the front (anterior) part of the cord. The major tracts that carry sensation to the brain are in the back (posterior) part of the cord
• Separating any two vertebral bodies is a soft elastic material called a disk. Lining the surface of the disk space of the two vertebrae on top and bottom are thin plates of cartilage

Pathology

Tumors of the spine originate from all the tissues that make up the spine and its contents as well as malignant tumors that metastasize (go to) the spine

• The most common tumors that grow from elements of the spinal cord are:
  1. Astrocytomas, which develop from the supporting cells of the spinal cord, are more common in children than in adults and are usually low grade (low malignant) tumors. Malignant astrocytoma, while the most common brain tumor, is rarely seen in the spinal cord (Figure 3)

Figure 3 - MRI showing a malignant tumor of the cervical spinal cord. A syrinx (cyst of the spinal cord) is seen above the tumor. Courtesy M. Muszynski, MD

2. Ependymomas are the most common benign spinal cord tumors in the adult and originate from the cells that line central canal of the spinal cord. These tumors grow very slowly and to considerable size and at times involve the entire length of the spinal cord (Figure 4)

Figure 4 - MRI showing a benign tumor of the spinal cord. Note that there is a syrinx both above and below the tumor.

3. Occasionally the central canal may dilate forming an out pouching of the central canal called a syrinx that may act as a tumor
• Hemangioblastoma is a vascular tumor that is composed of capillaries, well demarcated from surrounding tissue and may be multiple. Frequently the tumor may be associated with a cyst
• Meningiomas are benign tumors that come from the dura (Figures 5 and 6)
1. Meningiomas represent one-fourth of the tumors derived from tissues found in the spine
2. They are most commonly present in the thoracic spine in middle aged females
3. These tumors are rare in children

Figure 5 - MRI showing a benign tumor (meningioma) of the lumbar spine.	Figure 6 - Meningioma of the lumbar spinal canal as seen in surgery. Nerve roots of the cauda equina can be seen against the tumor.

• Neurofibromas and neurolemmomas (schwanommas) are similar benign tumors derived from nerve roots (Figures 7 and 8)
1. Neurofibromas are almost always associated with von Recklinghausen's disease (Neurofibromatosis) a disease in which multiple tumors derived from skin nerves form on the skin. This disease is frequently hereditary
2. These tumors may grow through the foramen between two vertebrae with part of the tumor lying within the spinal canal and part outside the spine. These tumors have a dumbbell shape with the thinnest part lying within the foramen
3. Occasionally neurofibromas may become malignant forming a neurosarcoma
4. Patients with neurofibromatosis may also develop meningiomas within the head and spine

Figure 7 - MRI showing a benign neurofibroma of the cauda equina outlined by arrowheads.	Figure 8 - Neurofibroma of the cauda equina as seen in surgery.

• Syrinx is a cyst that develops within the spinal cord. It may be associated with a tumor or be present by itself and act like a tumor. If the primary cause for the syrinx cannot be found and corrected, the cyst may be shunted with a small catheter into the subarachnoid space or even into the peritoneum of the abdomen (Figure 9)

Figure 9 - MRI showing two adjacent syrinxes of the thoracic spinal cord without apparent cause.

• Tumors can develop from other tissues found in the spinal canal
  1. Lipomas are tumors composed of fat
  2. Angiomas are derived from blood vessels
  3. Dermoid tumors contain skin elements that were trapped within the spinal canal during development
  4. Lymphomas are derived from lymph tissue
  5. Tumors of bone such as osteoma, chordoma, osteoid osteoma and multiple myeloma
• Metastatic tumors from cancer in other parts of the body frequently go to the spine lodging primarily in the vertebrae
  1. The most common metastatic tumors come from the lung, breast, prostate gland, kidney and thyroid gland
  2. In adults, metastatic tumors to the spine occur more frequently than tumors from tissues found primarily in the spine
  3. As these tumors grow, they compress the spinal cord or invade nerve roots to cause symptoms
  4. Some brain tumors may give off cells into the CSF that float down into the subarachnoid space of the spinal canal and develop into spinal tumors. Surgery is rarely necessary for these metastases

History and Examination

The history and examination of the patient varies depending on the type of tumor, the level of the spine involved, the rate of growth of the tumor and the structures being compressed or invaded by the tumor

• With benign tumors that grow slowly such as a meningioma or ependymoma the tumor may grow for years and attain a large size before symptoms cause the patient to go to a doctor. With more rapidly growing malignant tumors symptoms may develop within weeks or months
• Pain varies with the structures involved by the tumor. Tumor within the spinal canal may produce a dull back pain, typically occurring at night. Radiating pain into the arm, leg or chest wall may occur when the tumor irritates a nerve root. Severe back pain may occur when tumor invades the vertebrae
• Weakness or paralysis can occur. With nerve root involvement there may be local muscle weakness in the arm or leg while compression of the spinal cord can cause paralysis in the legs and, if in the neck, paralysis in all four limbs. Occasionally the patient may have ataxia (wobbly gait)
• The may be paralysis of bladder and/or bowel function
• Occasionally a patient may have increased pressure in the head possibly due to a block in the normal flow of CSF. This can cause headaches, dizziness, nausea and vomiting, light-headedness and blurring of vision
• Pressure on the spinal cord may cause an increase in the deep tendon reflexes (increase movement of the limb on tapping with a small hammer) and spastic gait
• There may be a clear loss of pain or touch sensation below a certain level of the body

Tests

• Plain X-rays of the spine are usually not too helpful. Occasionally the tumor may be calcified and show up on a plain X-ray, or the tumor has eroded the bone around a foramen
• Bone scan is particularly useful for identifying metastatic tumor in bone. This test is performed by injecting a radioactive 'dye' intravenously. The dye collects in the tumor and shows up on a scan
• Computerized Axial Tomography (CAT scan) is useful for those tumors that involve the vertebrae. It is particularly helpful when combined with an iodine containing 'dye' given intravenously that may concentrate in the tumor
• Myelogram is a test in which a contrast dye containing iodine is injected into the CSF and positioned about the tumor. CT scan following myelography is particularly useful in localizing a tumor
• Magnetic Resonance Imaging (MRI scan) has become the primary diagnostic test for spinal tumors, particularly if the scan is enhanced with gadolinium. Gadolinium accumulates in tumors as a result of leakage from abnormal tumor blood vessels. MRI does not image bone well and thus the soft tissues within the spine are more readily seen. (Figures 3,4,5,7 and 9)
• A CT scan of the chest and abdomen may be carried out to rule out the possibility of a metastatic tumor Indications and

Contraindications for Surgery

• Tumors of the spinal cord, dura and nerve roots usually require surgery. Small meningiomas and neurofibromas that do not cause symptoms, particularly in elderly persons, need not be removed but must be followed carefully. Patients with neurofibromatosis may have many small tumors involving multiple nerve roots. In this situation only symptomatic tumors are removed
• Metastatic tumors to the bone that do not cause spinal cord compression may be treated with radiation and chemotherapy
• Metastatic tumors to the spine in patients with multiple metastases to several organs and whose life expectancy is short are better treated with radiation and/or chemotherapy
• Patients with severe heart and lung disease are better treated with radiation and/or chemotherapy
• Bone tumors may be treated with needle biopsy of the spine followed by radiation and chemotherapy

Surgery

• Prior to surgery, the patient is evaluated by the anesthesiologist (see Anesthesia). Usually a general anesthetic is used. Blood hemoglobin level is obtained and blood for transfusion ordered and cross-matched as needed (Blood Transfusion)
• Steroid medication may be given to help in protecting the spinal cord
• In some instances the surgeon may monitor the ability of the spinal cord to transmit impulses (somatosensory and/or motor evoked potentials)
• Care is taken to be sure that the correct level of the spine is determined so that the incision is made over the correct vertebrae
• After the skin is cleaned and disinfected and sterilely draped, an incision is made in the skin over the tumor
• A laminectomy (removal of the lamina) is performed for most tumors of the spine that do not involve the bone
  1. The patient is placed on the operating table in the prone position (face down)
  2. For tumors in the cervical spine the head and neck are kept in a neutral position since undue flexion or extension of the neck may cause pressure on the spinal cord. Because placing a tube in the airway (endotracheal tube) may result in excessive extension of the neck, the tube is frequently inserted with the patient awake. This precaution is not necessary for tumors in the thoracic or lumbar spine
  3. The muscles are elevated and the spinous processes, lamina and facets are exposed
  4. The lamina and spinous processes are removed from at least one vertebral level above to one level below the length of the tumor (Figure 10A)
  5. Using a small burr and cutting tools called rongeurs, the lamina and spinous processes are removed. The ligament lining the inner surface of the spinal canal (ligamentum flavum) is also removed
  6. Ultrasound may be used over the dura to better localize the tumor before the dura is opened. The ultrasound unit connected to a computer produces a picture of the contents within the dura
  7. The dura is then usually opened in the midline (Figure 10B)

Figure 10a - Common approach for removal of tumors involving the dura and spinal cord. The laminae and spinous processes overlying the tumor are removed. © T. Graves	Figure 10b - The dura is opened in the midline. Note that the spinal cord blood vessels run in the midline. © T. Graves

8. The operating microscope is an important tool that allows the surgeon to more clearly see the tumor, blood vessels and the demarcation between tumor and normal tissue
9. Removal of the tumor depends on its position and attachments
• Tumor attached to the dura, such as a meningioma, is carefully separated from the spinal cord and nerve roots. (Figure 10 C1)The tumor may have to be debulked (removal of the center of the tumor) to reduce its size before separation. Care is taken to preserve all blood vessels going to nervous tissue and not tumor. The dura is cut around the tumor being sure that the entire tumor is removed. If tumor is firmly attached to nerve tissue and cannot be separated without causing paralysis or significant loss of sensation then it may be necessary that a small amount of tumor be left behind. The dura is then repaired with a dural substitute such as fascia lata (a fibrous tissue layer in the upper thigh), bovine pericardium (fibrous covering of the heart from a cow) or several other available materials (Figure 10D)

Figure 10c1 - A benign tumor (meningioma) attached to the dura is removed with the involved dura. © T. Graves	Figure 10c2 - A benign tumor (ependymoma) within the spinal cord. It is removed by opening the cord in the midline and dissecting the tumor away from the cord. © T. Graves

• Tumor within the spinal cord such as an astrocytoma or ependymoma is removed by carefully opening the spinal cord in the midline along the length of the tumor. (Figure 10 C2) If there is a clear plane between tumor and normal tissue, the tumor is carefully separated from the normal tissue. An ultrasonic aspirator (a tool that breaks up tissue into fine particles and sucks the material away) or laser may be used to remove tumor less traumatically
• Tumor attached to a nerve root such as a neurofibroma or schwanomma is carefully separated from the surrounding tissues such as spinal cord or other nerve roots. If the involved nerve root is no longer functional, it can be cut to remove the tumor (Figure 8)
• A syrinx that causes neurologic deficit for which no specific cause is found may require shunting the syrinx into the subarachnoid space or peritoneal cavity (Figure 11)

Figure 11 - Operative photo showing a silicone rubber catheter with one end in the syrinx and the other placed in the subarachnoid space.

10. After the tumor is removed, the dura is closed in a watertight manner. All bleeding is controlled and the wound closed in layers (fascia, subcutaneous tissue and skin) (Figure 10E)
• The surgical procedure for tumor involving bone, which is usually a metastatic tumor, varies with the location of the tumor in the vertebra. The aim of the surgery is twofold: take pressure off of the spinal cord or cauda equina and stabilize the bony spine

Figure 10d - . Following removal of a dural tumor, the part of the dura that is removed with the tumor is patched with artificial dura. © T. Graves	Figure 10e - After the tumor is removed the dura is closed in a water-tight manner with suture.

11. Tumor of the laminae and spinous processes and compressing the spinal cord from behind is removed through a midline incision similar to that described above. The muscles are separated off of the bone unless involved with tumor at which time the involved muscle may be removed. The involved bone and tumor is removed. The spine is stable and does not require any reconstruction
12. When the tumor involves the body and facets of the vertebrae, removal is more complicated. The tumor is removed from in front or from the side of the spine and replaced by bone or plastic
• In the neck the approach is from the front and is similar to that described for cervical discectomy, corpectomy and fusion. (Figure 12) The body of the cervical vertebra is removed. Whenever possible donor bone taken from the patient is used to replace the tumor ridden bone. If this is not practical then homologous (patient's own) or autologous (banked cadaver) bone or prosthesis may be used. The prosthesis is usually composed of polymethylmethacrylate, a plastic that is molded at the time of surgery to fit the cavity of the removed bone. Another method involves replacing the removed bone with a titanium cage filled bone chips. The bone or plastic may be supported with pins or plate
• In the thoracic spine the approach to the involved bone may be through the chest. In other cases the approach is through the back and the bone is exposed on the side where most of the tumor invades the body of the vertebra. The bone is then removed through the pedicle and the side of the body of the vertebra. Tumor removal is followed by replacement of the body with homologous or autologous bone or plastic supported with a plate. Various techniques may be used to accomplish the fusion
• In the lumbar spine the approach may be through the abdomen or, as in the thoracic spine, through the side of the vertebra as noted above

Figure 12a - Metastatic tumor involving the body of a cervical vertebra and compressing the spinal cord. © T. Graves	Figure 12b - The involved vertebra is removed along with the disk above and below. © T. Graves

Figure 12c - The body is replaced with bone from the patient, bone from a bone bank or, as seen here, a titanium cage filled with bone chips taken from the patient. © T. Graves	Figure 12d - A titanium plate may be used to give added support to the graft. © T. Graves

• When the tumor involves all or part of both the back and front of the vertebra, the tumor can be removed by approaching from both directions or may be approached from the back on the side of the tumor (Figure 13). Reconstruction of the removed vertebra involves stabilizing both the front and the back. The body is reconstructed as noted above. The back is supported with plates or with screws and hooks placed in the pedicles and laminae and locked together with rods (also see Lumbar Spinal Fusion)

Figure 13a - Tumor involving the right side of the spine and adjacent tissues (see C), that requires removal of the vertebra and reconstruction. The procedure approaches the tumor from the back and to the side of the spine. The laminae are removed. © T. Graves	Figure 13c - The tissues invaded by tumor (blue area) are removed. The body of the vertebra is split usually with an air driven bur. © T. Graves

Figure 13b - The posterior fixation device is applied to stabilize the vertebrae (usually only on the side opposite the tumor at first, which allows unobstructed approach to the tumor).© T. Graves	Figure 13d - The body of the vertebra is replaced by placing a plastic tube between the vertebral body above and below. The tube is filled through a side hole with methacrylate plastic that hardens in place. Additional methacrylate is placed around the tube. A titanium plate adds support. Bone (not shown) is placed along the spine posteriorly to fuse the bones together. © T. Graves

Complications

There is considerable variation in the types and severity of complications that can occur depending on the site and extent of the fusion.

• Bleeding or hemorrhage with the possible need for blood transfusions
• Untoward effects of the anesthetic (See Anesthesia)
• Further injury to the spinal cord with both paralysis, loss of sensation and bowel and bladder function
• Nerve root injury that could result in paralysis, loss of feeling, or loss of bowel and bladder control
• Infection in the surgical site, pneumonia, septicemia (infection in the blood) or meningitis
• Hemorrhage into the bowel (See Surgery of the Duodenum)
• Blood clots in the veins of the legs or pelvis which may also cause a pulmonary embolus
• Tear in the covering of the spinal cord or nerves with leaking of cerebrospinal fluid · Injury to major blood vessels
• Injury to the trachea, esophagus or nerves in the neck (See Cervical Discectomy)
• Injury to bowel or ureters
• Pneumothorax - air in the space between the lung and chest wall
• Kidney failure
• Confusion lasting several days
• Pseudoarthrosis- failure of the fusion to take place. Successful fusion may not be able to be determined for over one year
• Prolonged ileus, a condition in which the bowel stops functioning
• Pain from the bone graft donor site
• Dislodgment or backing out of the implant
• The possibility of unforeseen complications

Care After Surgery Care

Following removal of a tumor from the spine depends on the level of the surgery (cervical, thoracic or lumbar), the type of tumor, the stability of the spine and the preoperative condition of the patient

• The patient is frequently placed in the Intensive Care Unit for at least the first day
• Fluids are given by vein after surgery until fluids can be given by mouth. This progresses towards a regular diet
• If the bowel is not functioning properly, a tube may be placed into the stomach through the nose to keep the bowel from distending
• The patient may require bedside physical therapy
• A catheter may be placed to drain the bladder
• The patient's vital signs (blood pressure, pulse and respiration) are checked hourly until stable
• A brace may be necessary depending on the stability of the spine
• A check of neurologic function is carried out hourly for the first day
• To reduce the chance of clots in leg or pelvic veins the patient may wear elastic stockings, sequential compression boots that keeps blood in leg veins flowing and/or blood thinner to reduce the chance of clots and the chance of pulmonary embolus in which a clot goes to the lung
• Deep breathing and coughing is encouraged to keep lungs clear and reduce the chance of pneumonia
• The wound is examined for any redness or other evidence of possible infection
• Temperature of the patient is taken since this may be a sign of infection
• Steroids (cortisone) may be given especially if there evidence of neurological dysfunction such as weakness or loss of sensation
• Hospital stay is shorter when there is no neurological dysfunction while those with dysfunction may require prolonged rehabilitation

Care Following Discharge

• The surgeon usually sees the patient within two weeks of discharge
• The patient should watch carefully for any evidence of neurological dysfunction or infection
• A brace may be worn from three to nine months depending on the surgery
• Return to normal is variable depending on the presence of neurological dysfunction. A continued rehabilitation program may be necessary
• If cancer is present, radiation and/or chemotherapy may be necessary