Spinal Cord Tumors

Spinal Cord Tumors

Overview:

The spinal cord is an elongated, cylindric continuation of the medulla oblongata that extends from the cranial border of the atlas and terminates at the first lumbar vertebra. Spinal nerves enter and exit from the cord. Lumbar and sacral nerves form the cauda equina and remain in the canal until they exit at the appropriate level through the foramen. The spinal cord is protected by meninges, the same covering found the in brain, and is surrounded by fat tissue and blood vessels. The spinal cord resides within the spinal canal, which is formed by the spinal vertebra. As the canal is a fixed size, abnormal growth, edema, and inflammation from spinal cord tumors may quickly cause symptoms.

Etiology and Pathophysiology:

Spinal cord tumors can be primary or metastatic. These tumors are identified by the location of the origin of the mass:

  • Extradural: Lesions located outside the dura mater in either the epidural space or the bones of the spinal column or paraspinal tissue.
  • Intradural: Lesions located within or under the dura mater of the meninges.
  • Intramedullary: Intradural lesions arising within the substance of the spinal cord, within the tracts and central gray matter.
  • Extramedullary: Lesions arising outside of the spinal cord in the meninges, nerve roots, or vertebral bodies.

Spinal cord tumors are rare in terms of overall central nervous system tumors. Presenting symptoms depend on location of the lesion as well as the cell type. Metastatic extradural tumors causing epidural spinal cord compression are most commonly a result of lung tumors in men and breast tumors in women.

Extradural tumors:

Extradural tumors are usually malignant and produce a rapid onset of symptoms. Pain at the tumor site is common and occurs before the symptoms of spinal cord dysfunction. Early symptoms are a loss of bowel and bladder control. In fast growing tumors, symptoms can progress rapidly to paralysis. Approximately 15% of patients present with paraplegia, with half of them developing motor loss within 24 to 48 hours. Early recognition and prompt treatment (while the patient still has motor function) are the most important factors in preventing permanent and debilitating neurologic dysfunction.

Intradural tumors:

Intradural tumors account for 20% to 25% of spinal tumors, with one third of them being intramedullary (within the cord substance) and two thirds of them being extramedullary. The signs and symptoms of intramedullary tumors usually develop slowly and progressively as the cord is compressed. Pain is a common symptom at the time of diagnosis. However, the first symptom of an intradural tumor is often the loss of temperature and pain sensation, which develops as the ascending spinothalamic tracts of the cord are compressed or invaded by tumor. Local, radicular pain (pain that follows a nerve root) is often an early sign of extramedullary tumors, with neurologic dysfunction a later sign.

The pathophysiology of a spinal cord tumor also depends on the cell type. The histologic types of intradural spinal cord tumors are neurilemomas (schwannomas, neurofibromas), meningiomas, astrocytomas, ependymomas, and sarcomas.

Neurilemomas:

Neurilemomas are the most common intradural primary tumors of the spinal cord and are classified as schwannomas, or neurofibromas. They arise from the nerve root sheaths and are therefore found in the spinal, cranial, and peripheral nervous systems. Most commonly they are extramedullary. The majority of these nerve sheath tumors arise in the dorsal nerve root. They tend to involve the spinal can cranial nerves. The tumors are neurofibromatosis, or von Recklinghausen’s disease, are of the neurilemoma type.

Meningiomas:

Meningiomas are well-circumscribed intradural or extramedullary primary tumors that arise from the arachnoid cells. They occur most often in the thoracic area and are more prevalent in women than in men. They are usually loosely attached to the dura, which permits easy surgical removal. They may also erode into bony structures.

Astrocytomas:

Astrocytomas are most often intradural and intramedullary. They are the common type of intramedullary spinal cord tumor in adults and children. They occur most often through the fifth decades of life an are more common in males than in females. Similar to the classification of brain tumors, astrocytomas occur along a continuum of grades I to IV. The majority of spinal cord astrocytomas are grade I, with 75% being low-grade gliomas. Grade II tumors contain a number of anaplastic cells, and grade III and grade IV tumors are considered malignant. A malignant astrocytoma may quickly lead to rapid neurologic deterioration and death.

Ependymomas:

Ependymomas can be found throughout the spinal cord and tend to be intradural and intramedullary. More than half occur in the fourth and fifth decades of life, and approximately one third of them involve an increased number of anaplastic cells. Unlike astrocytomas, ependymomas tend not to invade normal tissue. They can therefore be debulked with minimal morbidity. The 10-year survival rate is greater than 90% without further treatment. Radiation is indicated only in those with anaplastic cells.

Sarcomas:

Sarcomas are malignant tumors that arise from mesenchymal tissue and have very little connective tissue. Examples are fibrosarcomas and liposarcomas. Sarcomas account for approximately 10% of all intradural extramedullary spinal cord tumors.

Other types of tumors include epidermoids, dermoids, teratomas, and hemangioblastomas. These make up about 15% of the total number of intradural spinal cord tumors, with each type accounting for less than 2% of such tumors.

Assessment:

Many factors must be included in the assessment and history of the patient with a spinal cord tumor. Often, a complete neurologic exam can locate the level of the lesion, allowing accurate diagnostic imaging and work up to begin. These factors include:

  • Pain: Many spinal cord tumors present with pain as the initial symptom. The pain is thought to be caused by compression, invasion of the spinal tracts, tension on the nerve roots, or attachment to the dura. Extramedullary and extradural spinal cord tumors can cause severe local pain and tenderness. Intramedullary tumors can cause pain, but this is usually less severe. Radicular pain runs through the distribution of the nerve root that is affected. Pain caused by a spinal cord tumor is aggravated by bedrest and is therefore worse at night (remember that pain from a herniated disk is usually improved by rest).
  • Sensory impairment: Sensory disturbances depend on the degree to which ascending fibers of the spinal cord are affected. Affected dorsal columns produce impairments of light touch, joint and position sense, vibration, two-point discrimination, and stereognosis. When the fibers of the anterolateral columns are affected, impairment of pain and temperature discrimination results.
  • Motor impairment: In general, motor weakness is a late symptom of a spinal cord tumor. Weakness is due to the involvement of the pyramidal or corticospinal tract. The degree of motor impairment may range from clumsiness to complete quadriplegia. Myelopathy may be evident with central spinal cord tumors, resulting in spasticity, paresis, hyperactive reflexes, Babinski’s sign. Some patients may develop a syrinx, which is a fluid filled area in the center of the spinal cord caused by pressure on the cord from a tumor, trauma, or after surgery. Diffuse motor deficits may be noted in those with a syrinx. These symptoms can be unilateral or bilateral, and are usually slow to develop.
  • Sphincter control: Disturbances of sphincter control, with a loss of bladder and bowel control, can occur as late symptoms of a spinal tumor. When the tumor causes pressure on the second or third sacral nerve roots, micturition is affected and there is paralysis of bladder contractions, bladder distention, and retention of urine with overflow incontinence. Urinary incontinence is often associated with a syrinx when the lesion causes disruption of the sacral pathways. Sexual dysfunction may also occur in association with loss of sphincter control.
  • Lesion levels: Along with a baseline assessment of pain, sensory impairment, motor impairment, and sphincter control, the clinician must ascertain whether the lesion is at the cervical, thoracic, or lumbar level of the spinal cord.
    • Cervical lesions
      • Lesions at the level of the foramen magnum (the upper cervical segments) can be complicated. Patients may hold their head stiffly and have difficulty with shoulder elevation. Lesions at the C4 level can be particularly dangerous because of the phrenic nerve (which controls the diaphragm). With lesions involving the unilateral cord, the patient may experience respiratory difficulty and bilateral respiratory failure. High cervical lesions also produce quadriplegia, occipital headaches, stiff neck, and downbeat nystagmus.
      • Lesions below the C4 level are less life threatening because the phrenic nerve is spared. Pain and muscle weakness follow patterns according to root distribution.
      • Horner’s syndrome may occur with lesions at the cervicothoracic junction (C8) as a result of automatic nervous system dysfunction. Horner’s syndrome includes ptosis of the eyelid with pupillary constriction (miosis) and anhydrosis on the affected side. This can occur unilaterally or bilaterally.
    • Thoracic lesions
      • Metastatic lesions from the lung tend to spread to the thoracic area. Whether metastatic or primary, lesions of the thoracic region are more difficult to localize than are cervical or lumbar lesions. Pain and sensory changes usually precede muscle weakness. Sensory changes are relatively easy to identify because of the regular bandlike distribution of the dermatomes at this level.
      • Beevor’s sign maybe present with a lesion at the T10 level. When a patient sits up or raises the head from a recumbent position, the umbilicus is displaced toward the head. This is a late sign and occurs secondary to paralysis of the interior portion of the rectus abdominal muscle.
    • Lumbar lesions
      • Patients with cancer of the lung, breast, prostate, and kidney may have metastases to the lumbar or cauda equina region. Whether metastatic or primary, lesions of the lumbar and cauda equina region are characterized by pain, paresis, and a loss of strength in the lower extremity muscles. The pain can be very severe, and early loss of sphincter control is not uncommon.
        • Cauda equina syndrome is the compression (or injury) of any of the lumbosacral nerve roots within the neural canal below the level of L1. The patient may experience an areflexic bladder and bowel with varying degrees of motor/sensory impairment depending on the level and severity of compression. As peripheral nerves are able to regenerate, recovery is often possible in this situation.
        • Conus medullaris syndrome occurs with damage to the gray matter in the lower lumbar and sacral portion of the spinal cord and may also include nerve roots within the spinal canal. Again, the patient may experience areflexic bladder and bowel with varying degrees of motor/sensory impairment. Unfortunately, conus injuries have much less chance of return of function compared to cauda equina injuries.

Neurodiagnostics and Laboratory Studies

Many neurodiagnostic studies are used in the initial evaluation of spinal cord tumors. Understanding the probable pathology based on comprehensive examination is important in ordering the appropriate imaging study or lab test. In current cost-driven health care markets, the choice of studies is based on availability, perceived accuracy of the test, patient tolerance, and physician familiarity and comfort with the study.

  • Myelography: Useful in obtaining information about the characteristics, location, and spatial relationships among spinal structures. Can demonstrate the level of a lesion, widening of the cord, and blockage of CSF.
  • CT: Beneficial in diagnosing lesions affecting the vertebral column. Useful in assessing bony defects and invading tumors.
  • MRI: Provides the most detail of the pathologic condition of the spinal cord and surrounding soft tissue. The best test for syrinx evaluation. Gadolinium should be used for tumor evaluation. It is useful for differentiating infections from intramedullary lesions.
  • SPECT: Useful for localizing metastatic lesions. Can define the site of the lesion within a given vertebra (pedicle vs. facet).
  • Plain x-rays: While helpful in imaging spinal tumors, they do not image the spinal cord. Should be used in conjunction with an MRI.

Treatment

After diagnostic workup, spinal cord edema (swelling) should be managed preoperatively with oral or IV steroids. Edema is most commonly managed with a corticosteroid such as Decadron (dexamethasone). Presenting symptoms may improve as the edema is reduced.

The primary treatment for spinal cord tumors is surgical resection. If possible, the entire lesion is removed. However, additional consideration should be given to structure deterioration of the spinal column. If the tumor is lytic (invades bone), stability of the spinal column may be affected, resulting the need for instrumentation and fusion. If the tumor is not able to be completely resected, the spinal canal and affected neuro structures should be decompressed as fully as possible.

Subsequent treatment depends on the pathology of the tumor. Radiation therapy and stereotactic radiosurgery are common postoperative treatment for most spinal cord tumors. Few tumors, such as a meningioma, require only surgical decompression. No further treatment is necessary. But for most tumors, radiation is required. For many metastatic tumors, prognosis is poor, so radiation is considered palliative treatment.

Chemotherapy is tumor specific and considered appropriate for ependymomas, astrocytomas, and metastatic disease from lung, breast, colorectal, melanoma, lymphoma.

For more information call 920-882-8200 or 1-888-231-5236

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