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Spinal Cord Infarction


Practice Essentials

A basic knowledge of the signs and symptoms of acute spinal cord dysfunction are required in order to perform a relevant history and physical examination. A spinal sensory level is classically found, but sensory complaints and findings limited to the distal extremities can also be seen early in the course of spinal infarction. Typically onset is apoplectic, evolving in minutes or a few hours to produce severe dysfuction of sensory and motor systems.

Background

Occlusive vascular lesions affecting the spinal cord (spinal stroke) are diagnostic challenges. As is the case for the more common cerebrovascular accident affecting cerebral circulation, an acute onset is a clue to the diagnosis. The circulation to the spinal cord has unique features related to the rich anastomotic anatomy of the cord that result in relative rarity of spinal cord infarction in comparison to cerebral infarction, as described in the images below.
Transverse section of spinal cord showing locationTransverse section of spinal cord showing location of main pathways. The lamination of fibers in posterior columns and in lateral spinothalamic and lateral corticospinal tracts is indicated (C, cervical; T, thoracic; L, lumbar; S, sacral).
Simplified representation of course of major sensoSimplified representation of course of major sensory pathways in the spinal cord. Decussation of the spinothalamic tracts occurs within one or two segments of their entry.
Pattern of arterial supply to spinal cord and (lefPattern of arterial supply to spinal cord and (left) territories of the anterior and posterior spinal arteries.

Pathophysiology

The anterior spinal artery is a single long anastomotic channel that lies at the mouth of the anterior central sulcus and supplies the circulation to the anterior two thirds of the spinal cord, shown below.
Pattern of arterial supply to spinal cord and (lefPattern of arterial supply to spinal cord and (left) territories of the anterior and posterior spinal arteries.
It gives origin to sulcal arteries that take an arching course to one or the other anterior gray horns. The posterior spinal arteries are smaller paired arteries lying just medial to the dorsal roots. The arterial supply of the spinal cord arises from the aorta and at its cephalad and caudal ends from tributaries of the subclavian and iliac arteries. Eight to ten unpaired anterior medullary arteries are branches of the larger afferent aorta and vertebral and iliac arteries. The largest anterior medullary artery, the great anterior medullary artery of Adamkiewicz, which is susceptible to occlusion with neurologic deficit, is located at the lumbar enlargement, usually at L2 on the left side (but may be at any point from T8 to L2).

Epidemiology

Frequency

United States
Spinal cord infarction is not common, but only fragmentary or indirect data are available on incidence or prevalence. A large study showed that only 9 of 3784 autopsies revealed spinal cord infarction, with a rate of occurrence of 0.23% at death. Conversely, if spinal stroke is approximately 1.2% of strokes, an overall annual incidence of 12 in 100,000 can be estimated.
International
International incidences are also unclear. Recent reports that describe patients developing spinal cord infarction in an increasing number of situations and pathologies would influence this because procedures ranging from major surgery to injections for epidural anesthesia, infections and especially meningitis, and medications vary in different countries.

Mortality/Morbidity

The risk to life and its quality from spinal cord infarction is substantial because of the disability, which can be severe, with paraplegia, risk of pulmonary emboli, and risk of infection (eg, bladder, lungs, decubiti). However, no epidemiologic studies are available because of the relatively small number of patients affected.
Published series of reports of spinal cord infarction are relatively small, ranging up to 36-44 patients. [1They find a mortality rate in the vicinity of 20-25% for patients admitted to hospital with spinal cord infarction. [2 No relationship to age is reported. However, the reported series do have a median age of 52 years.

Prognosis

Although prognosis is guarded, with many or most patients remaining severely weak and with with severe bladder dysfunction, up to one-third to one-half of patients experience slow recovery of at least a moderate nature.

History

Spinal cord infarction is usually marked by an acute onset, often heralded by sudden and severe spinal (back) pain, which may radiate caudad. This is associated with bilateral weakness, paresthesias, and sensory loss. Loss of sphincter control with hesitancy and inability to void or defecate becomes evident within a few hours.
The spinal cord stroke, either ischemic or hemorrhagic, has an acute and often apoplectic onset evolving over minutes. This is emphasized because many of the confounding diagnoses, including acute transverse myelopathy, viral myelitis, Guillain-Barré syndrome, and mass lesions in the spinal canal, develop over 24-72 hours with an acute but discernibly slower evolution than the vascular lesions. Reports emphasize the occasional confusion of this diagnosis with angina pectoris or acute myocardial infarction. [34]
Neurologic deficit may occur without pain, but most (>80%) spinal infarcts are painful. This is an interesting and unexplained difference from cerebral infarction, which is usually not painful. The mimic of coronary ischemia is seen because of the occurrence of chest pain, which may be severe.
Uncomplicated spinal cord infarction is most commonly thoracic (with peak at T8 in the series reported by Cheshire), [1and presents as acute paraparesis or paraplegia, numbness of the legs, and inability to void. [4]
The syndrome depends on the level of the cord lesion and may vary from mild or moderate and even reversible leg weakness to quadriplegia. A guide to determine the spinal cord level is below.
Guide to clinical determination of the segmental sGuide to clinical determination of the segmental spinal cord level.
Fever is a warning ("red flag"); heed this warning by considering infectious origins of a spinal cord syndrome, particularly acute bacterial meningitis, and focal extramedullary spinal lesions (eg, epidural and subdural abscess, granuloma) and viral myelitis due to herpes simplexvaricella-zoster, and other viruses.
Many reports exist, and these are usually of single or a few cases of spinal cord infarction occurring in context of and classed as complications of surgical procedures in which hypotension and prolonged positioning (eg, seated neurosurgical approaches, hyperlordosis) may be prominent factors. Also, aortic surgeries, injections for foraminal nerve block for epidural anesthesia, or even self-injection by the addict seeking an intravenous access [456789have been reported in association with and probably causative of spinal cord infarction.

Physical

Neurologic dysfunction usually (ie, in approximately 95% of reported cases) stems from a lesion located in the anterior two thirds (or in the central "watershed") of the spinal cord and spares vibration and position sense perception, which are carried by the posterior columns and are relatively spared. The images below depict sensory pathways in the spinal cord and vascular anatomy of the spinal cord in the axial plane.
Simplified representation of course of major sensoSimplified representation of course of major sensory pathways in the spinal cord. Decussation of the spinothalamic tracts occurs within one or two segments of their entry.
Pattern of arterial supply to spinal cord and (lefPattern of arterial supply to spinal cord and (left) territories of the anterior and posterior spinal arteries.
In the acute stage (usually for several days),"spinal shock" with flaccid muscle tone and areflexia, including absent Babinski reflexes, is observed commonly.
The classic presentation is a sensory pattern distal to the lesion, superficial pain and temperature discrimination are lost bilaterally with relative preservation of light touch, vibration, and position sense. The image below provides a guide for clinical determination of spinal level.
Guide to clinical determination of the segmental sGuide to clinical determination of the segmental spinal cord level.
Weakness and sensory loss (for all primary sensory modalities) are found at the spinal cord segmental levels of the spinal cord infarct.

Causes

Identifying the cause of spinal cord infarction according to clues related to the location of the vascular pathology is generally attempted. The pathology may involve the aorta or an intervening arterial feeder (eg, thoracic, intercostal, or cervical branch from subclavian or vertebral artery), or the radicular artery may affect the anterior spinal artery and intrinsic arterial vessels within the spinal cord. Spinal venous pathology may produce spinal infarction, although this is clinically rare.
  • Involvement of intrinsic cord vessels has been reported as a manifestation of degenerative arteriosclerosis (with typical risk factors, most notably age related), but infarction of the spinal cord remains rare in this high risk group relative to infarction of other organs, due to the rich anastamotic network of the spinal cord.  Equally rare, but with demographics tilted towards a younger group on average, is infarction with arteritis, both in systemic lupus erythematosus and granulomatous arteritis.   Varicella zoster virus is known to induce arteritis and can rrsult in the same acute process.
  • Emboli consisting of intervertebral disk fragments have been reported to enter and occlude arteries supplying the spinal cord, not only in humans, but in other large vertabrate animals..
  • Anterior spinal artery occlusion has been reported with arteritis, including that associated with syphilis and diabetes mellitus; after trauma; spontaneously or without recognized cause; and as a complication of spinal angiography, cervical spondylosis, spinal adhesive arachnoiditis, administration of intrathecal phenol, and spinal anesthesia.
  • Aortic disease has produced spinal infarction in a variety of situations including dissecting aneurysm; aortic surgery, especially with aortic cross-clamping above the renal artery (below that level anastomotic flow via the artery of Adamkiewicz usually provides protective circulation); aortography; atherosclerotic embolization; and aortic thrombosis.
  • Uncommon causes include decompression sickness, which has a predilection for spinal ischemic damage; complications of abdominal surgery, particularly sympathectomy; circulatory failure as a result of cardiac arrest or prolonged hypotension; and vascular steal in the presence of an arteriovenous malformation, or vascular compression by tumors in the spinal canal, vertebral fracture, and treatment of migraine headache with zolmitriptan.

Diagnostic Considerations

The top priority is to exclude spinal cord compression by a mass lesion. The pathologies associated with spinal cord infarction are numerous and include neoplasm, spinal epidural or subdural abscess, granuloma, spinal epidural or subdural hematoma, extramedullary spinal tumor (including meningioma, neurofibroma, extradural lymphoma, metastasis), and herniated intervertebral disk. Compressive lesions  are "surgical" causes and require prompt diagnosis because of the urgent clinical need for decompression.
Differentiate spinal cord infarction from acute inflammatory demyelinating polyradiculopathy (AIDP, Guillain-Barré syndrome) by following the diagnostic criteria for AIDP. The ADIP radiculopathy usually does not involve sphincter dysfunction and has a different pattern of sensory deficit (typical of peripheral neuropathy), with distal loss in the extremities and lacking a sensory level on the body.
Intraspinal hemorrhage (hematomyelia): Consider the possibility of an underlying arteriovenous malformation of the spinal cord. This is especially important because surgical extirpation may prevent recurrence of hemorrhage and/or progression to more severe disability such as complete paraplegia.
Acute myelopathy
Acute transverse myelopathy
Viral myelitis
Demyelinating disease
Parasitic diseases (schistosomiasiscysticercosis)

Differential Diagnoses


Laboratory Studies

Routine CBC; fasting serum glucose; erythrocyte sedimentation rate; lipid panel for cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides; serologic test for syphilis, and; electrolytes
Leukocytosis, including a left shift to polymorphonuclear WBCs, suggests an infectious myelitis or other infectious cause of spinal cord compromise.
Diabetes mellitus is present in approximately one half of patients with epidural abscess and is a vascular risk factor. Other risk factors including the metabolic syndrome with obesity and hypertension may also be relevant.
On rare occasions, hypokalemia or hyperkalemia presents with flaccid quadriparesis, which is in the differential diagnosis of myelopathy.
Tests for vascular risk factors, especially diabetes mellitus, hypercholesterolemia, coagulopathies, and systemic lupus erythematosus and other forms of arteritis and vasculitis. The diagnosis of giant cell arteritis may be suspected by an elevated ESR but requires temporal artery biopsy for confirmation.
The search for vascular risk factors extends from diabetes mellitus (ie, fasting serum glucose), hypertension, and hypercholesterolemia (ie, lipid panel for low-density lipoprotein, very low-density lipoprotein, and high-density lipoprotein) to anticardiolipin or antiphospholipid syndromes (ie, activated partial thromboplastin time, antiphospholipid antibody titer) and other coagulation disorders, such as protein C and protein S deficiencies and thrombocytosis or thrombocytopenia (eg, thrombotic thrombocytopenic purpura [platelet count]). [1617]
The less common causes usually are sought only if no obvious vascular risk factor is found in a young patient with a spinal cord infarct.
Infectious causes are those that can be defined by examination of blood or cerebrospinal fluid (CSF). The infectious causes range from syphilis (eg, serum rapid plasma reagin [RPR], Venereal Disease Research Laboratory [VDRL] test, or Wasserman, CSF VDRL or Hinton) to viruses that can be identified specifically by polymerase chain reaction (PCR), such as herpes simplex type 1 and 2varicella-zosterEpstein-Barr, human T-cell leukemia type 1 (HTLV-1), HIV, and hepatitis B.
Autoimmune assessment of blood and CSF extends from screening by erythrocyte sedimentation rate (ESR), antinuclear antibody (ANA), and complement level assay to immunoassay determination of nuclear antibodies.

Imaging Studies

A crucial examination is the imaging that can identify (or exclude) a mass or space-occupying lesion that is compressing or compromising the circulation of the spinal cord (extraaxial) or is within the cord tissue (intraaxial). The easiest and safest procedure for this is spinal MRI. [456789Take care to avoid the pitfall of limiting the spinal region studied by failing to appreciate that high cervical regions have little local symptomatology or signs. Another diagnostic pitfall is failing to appreciate that a sensory level may be caudad to the lesion because of the topographic lamination with superficial location of the ascending sensory pathways (lateral spinothalamic tracts) from the lower spinal segments; this also may limit the spinal region studied.
Delineation of the spinal cord infarct has been the greatest advance in recent years. Numerous reports of central high-intensity lesion delineation appropriate to the cord lesion are available. [1617181910Diffusion weighted imaging (DWI) is particularly sensitive to the ischemic change and may become standard at least in the specialized treatment centers that are best for these patients. Case studies outline important differences in spinal cord infarct versus transverse myelitis seen on MRI. [20]
Myelography, especially with the greater sensitivity of the enhanced CT myelography, is satisfactory for definition of mass lesions and can be used if MRI is unavailable or for any reason unsatisfactory (eg, a very obese patient). Parenthetically, the latest of the open-frame MRI equipment appears to be satisfactory for spinal diagnosis.
A diagnostic pearl is to use cranial MRI. It is valuable in the patient with multiple sclerosis because the abnormalities found provide confirmatory evidence. This principle is also true for other multifocal CNS diseases such as systemic lupus erythematosus, infectious disorders, and sarcoid.
A diagnostic pitfall to remember is the "cerebral" paraparesis that can occur in such parasagittal disorders as parasagittal meningioma or epidural empyema/abscess. Bilateral anterior cerebral artery ischemia also can occur in the anomalous common stem of these arteries.
Spinal CT scan has little application to the diagnosis of spinal ischemia. It lacks the sensitivity, especially in the cervical region, to be adequate for reliable exclusion of several of the mass lesions in the differential diagnosis. Likewise, little value is found in plain radiography of the spine for the diagnoses considered here.
Spinal angiography (arteriography) is indicated occasionally, usually for diagnosis and treatment of a spinal arteriovenous malformation. The procedure is technically difficult and somewhat risky and usually is performed only at tertiary care medical facilities. Spinal MRI has achieved a level of sensitivity and reliability that it may suffice although for the definitive diagnosis of spinal AVM, spinal angiography is often indicated.

Other Tests

Electromyography (EMG) and nerve conduction velocity (NCV) determination will reveal deficits in H and F waves early after the onset of ischemia and subsequent loss of motor action potentials and changes of denervation. These occur because of the loss of anterior horn and other cells in the spinal cord.
For differentiating spinal cord infarction from polyneuropathy: EMG and NCV findings are usually (approximately 75%) abnormal in AIDP and can be of value in this differential consideration. Enhancement of the nerve roots after gadolinium administration appears to be specific and useful in making the diagnosis of AIDP.

Procedures

CT-guided biopsy or culture may be diagnostic in some of the diagnostic differential pathologies. It is not indicated for the diagnosis of most spinal ischemia.
Surgical biopsy sometimes is indicated for diagnosis of differential possibilities including neoplasm, meningeal tumor or sarcoidosis, granuloma, and focal indolent infections.
Temporal artery biopsy can confirm the diagnosis of giant cell arteritis that can underlay spinal cord infarction.
CSF examination is useful for determining any abnormality that is not fully specific but suggests inflammatory (including neurosarcoidosis) or neoplastic causation. This is typically increased cell counts and pleocytosis, increased CSF protein, and occasionally decreased CSF glucose.
An increase in CSF immunoglobulin G (IgG index) or an oligoclonal heterogeneity of immunoglobulins suggests multiple sclerosis, although oligoclonal banding can also be found in other inflammatory disorders including sarcoidosis, viral pathologies, and autoimmune diseases.
Specific diagnoses of the viral myelitides are now possible by PCR. This promises to revolutionize the specific diagnosis of the intraaxial myelopathies.
Confirming diagnosis of a focal spinal lesion of bacterial, mycobacterial, fungal, or parasitic origin by culture is rare, but still worth pursuing in the patient whose disorder is worrying.

Histologic Findings

Histologic findings are appropriate to the pathologies outlined in the preceding section. See the image below for a spinal cord transverse section.
Transverse section of spinal cord at T12-L1 showinTransverse section of spinal cord at T12-L1 showing infarction of central cord. The patient became paraplegic following resection of a ruptured abdominal aortic aneurysm. During surgery, prolonged occlusion of the abdominal aorta and great ant

Medical Care

The standard drug therapy is aspirin. This is based upon the consensus recommendation for acute treatment of ischemic stroke at any site. Clopidogrel and a combination of aspirin and controlled-release dipyridamole also may be of benefit in reducing the risk of myocardial infarction, recurrent stroke, and death. No direct studies have examined efficacy of drug therapy in spinal cord infarction. This is because of the uncommon nature of the disorder and frequent delay in diagnosis. However, a multicenter study of these therapies would be possible and may yet be done.
The standard measures for management of the complications of acute paraplegia, directed at prevention of peripheral thrombophlebitis and pulmonary embolism, are recommended. These include pulsatile leg wraps, low-dose heparin administered subcutaneously, and physiotherapy.
Neuroprotective strategies, including antioxidant, antiglutamatergic, and protease inhibition, improve outcome in animal experimentation with models of acute ischemia but have not yet been reported effective in human cord ischemia. One would hope that these approaches are more vigorously pursued as research into modes of preventing cell death progresses.
Anticoagulation is considered at 2 dosage levels with different rationales (see above). It is considered at low dosage with the goals of preventing peripheral venous thrombosis and reducing the risk of pulmonary embolism, and it is considered at higher dosage with the goals of preventing extension of the acute ischemic injury and, over the longer term, of reducing recurrent morbidity and mortality rates. However, as stated previously, no definitive studies define the use of anticoagulation in spinal cord infarction.

Consultations

If compressive lesions are observed, consultation with a neurosurgeon may be warranted. Physiatry or neurorehabilitation specialists may be consulted to implement rehabilitiation measures, including prevention of decubiti and spasticity.

Diet

Diet is not directly relevant. A diet with a high fiber content prevents constipation.

Activity

Early in the course, transfer to chair and ambulation as possible adjuncts to rehabilitation and to prevent thrombophlebitis and pulmonary embolization.


Medication Summary

In general, the prophylaxis of stroke by inhibition of platelet aggregation is prudent and recommended. If an unusual cause for the spinal thrombosis is suggested, such as vasculitis or infection, one must consider drugs effective in that disorder including steroids and antibiotics, respectively.
Inhibition of platelet aggregation should be implemented with the goals of limiting extension of the acute ischemic lesion and reducing the longer-range risks of recurrent stroke, myocardial infarction, and death.
To this point, there have been no reports of the use of thrombolytic agents such as tissue thromboplastin activator in spinal cord infarction.

Antiplatelet agents

Class Summary

These agents inhibit platelet function by blocking cyclooxygenase and subsequent aggregation. Antiplatelet therapy has been shown to reduce mortality rate by reducing the risk of fatal strokes, fatal myocardial infarctions, and vascular death in patients with a history of transient ischemic attacks.

Aspirin (Anacin, Ascriptin, Bayer Aspirin)

Inhibits prostaglandin synthesis, preventing formation of platelet-aggregating thromboxane A2. May be used in low dose to inhibit platelet aggregation and improve complications of venous stases and thrombosis.

Clopidogrel (Plavix)

Selectively inhibits ADP binding to platelet receptor and subsequent ADP-mediated activation of glycoprotein GPIIb/IIIa complex, thereby inhibiting platelet aggregation.

Aspirin with dipyridamole SR (Aggrenox)

Drug combination with antithrombotic action. Aspirin inhibits prostaglandin synthesis, preventing formation of platelet-aggregating thromboxane A2. May be used in low dose to inhibit platelet aggregation and improve complications of venous stases and thrombosis.
Dipyridamole is platelet-adhesion inhibitor that possibly inhibits RBC uptake of adenosine, itself an inhibitor of platelet reactivity. In addition, may inhibit phosphodiesterase activity, leading to increased cyclic-3', 5'-AMP within platelets and formation of potent platelet activator thromboxane A2.

Spinal Tumors Treatment & Management


Background

Primary spinal tumors fall into a distinct category because their timely diagnosis and the immediate institution of treatment have an enormous impact on the patient's overall prognosis and hope for a cure.

Generally, with spinal pathology, problems that arise are either chronic problems related to degenerative disease or deformity or acute manifestations of traumatic sequelae. When considering tumors of the spine, one must consider the different tissue types around the spinal column. The presence of neural tissue, meningeal tissue, bone, and cartilage makes any of these tissue types a possible nidus for neoplastic change. Also, metastatic lesions may spread to the spine from distant primary tumor sites by hematogenous or lymphatic routes.

Primary nonlymphoproliferative tumors of the spine are uncommon and make up fewer than 5% of bone neoplasms; the annual incidence of primary spine tumors is in the range of 2.5-8.5 per 100,000 population. Metastatic disease of the spine is much more common. Approximately 40-80% of patients who die of cancer have bony metastases at the time of death, with the spine being the most common metastatic skeletal location.

Neoplastic disease, however, can present with back pain that is indistinguishable from back pain resulting from more benign causes. Therefore, the physician caring for patients complaining of back pain is faced with the challenges of (1) distinguishing benign causes from those that can be neurologically or systemically devastating and (2) prescribing the appropriate treatment.

This distinction sometimes can be difficult to make because of the complicated architecture of the spine (see Anatomy). The physician must consider differential diagnoses of degenerative processes, infections, muscular strains, neurologic impingements, and, finally, neoplastic processes. With thorough history taking, physical examination, and diagnostic imaging, the physician can acquire enough information to make the correct diagnosis in an efficient manner. [1]

Anatomy

The spine consists of 33 vertebrae that form the bony spinal column. The spinal column can be divided into the cervical, thoracic, lumbar, and sacrococcygeal regions. Although morphologically distinct, each vertebra in the subaxial cervical, thoracic, and lumbar spine has a complex architecture, consisting of a vertebral body, pedicles, laminae, and spinous and transverse processes.

The bony canal provides protection and support to the fragile spinal cord and nerve roots within the dural sac. The soft tissues surrounding the bony spine vary by location from the thick dorsal paraspinous musculature to the vital organs and vessels within the mediastinal, thoracic, peritoneal, and retroperitoneal spaces.

Prognosis

Chang et al conducted a study to evaluate local control rate and to identify prognostic factors after stereotactic radiosurgery for treatment of primary malignant spinal tumors. [2 Median age of the 29 patients was 46 years (range, 11-68). Histologic diagnoses included chordoma (n = 1), chondrosarcoma (n = 5), osteosarcoma (n = 3), synovial sarcoma (n = 3), plasmacytoma (n = 2), Ewing sarcoma (n = 2), malignant peripheral nerve sheath tumor (n = 2), and malignant fibrous histiocytoma (n = 1). Mean follow-up was 50 months (range, 8-126).

Surgical resection was the initial treatment in 25 cases, percutaneous biopsy in four. [2 Stereotactic radiosurgery was used as primary treatment in 14 cases and as salvage treatment for progressive lesions in 15. Eleven patients had undergone previous conventional external-beam radiation therapy before stereotactic radiosurgery. Median tumor volume was 14 cm3 (range, 2.0-235). Delivered radiation doses were 12-50 Gy in two to six sessions. The mean radiation dose converted into a biologic effective dose (BED) was 60 Gy (range, 43-105).

Mean overall survival was 84 months for chordoma patients and 104 months for sarcoma patients. [2 The investigators found no factors that affected overall survival. The mean local progression-free survival was 56 months for chordoma patients and 73 months for sarcoma patients. The recurrent mode of presentation was predictive of local progression of spinal sarcomas. For patients with chordoma, no factors were found to correlate with local recurrence.

Kose et al conducted a study of the effect of early rehabilitation on neurofunctional outcome after surgery in children with spinal tumors. [3 The investigators reviewed medical charts and radiographic records of 70 pediatric patients (aged 1-17 years) who underwent surgery for the removal of spinal tumor. The patients received rehabilitation treatment beginning 4 days (range, 2-7 days) after surgery for 10 days (range, 7-23 days).

Results were assessed on the basis of scoring on the Modified McCormick Scale, the Functional Independence Measure for Children, the American Spinal Injury Association Impairment Scale, and the Karnofsky Performance Status Scale. [3 Sensory function, motor function, and activity of daily living were significantly improved for the patients who received early rehabilitation. Tumor setting, the level of localization, and the patients' clinical symptoms had no bearing on neurofunctional outcomes.


History and Physical Examination

The most common clinical presentation associated with all spine tumors is back pain that causes the patient to seek medical attention. Back pain is the most frequent symptom for patients with either benign or malignant neoplasms of the spine. Neurologic deficits secondary to compression of the spinal cord or nerve roots also can be part of the presentation.

The degree of neurologic compromise can range from slight weakness or an abnormal reflex to complete paraplegia, depending on the degree of encroachment. The loss of bowel or bladder continence can occur from neurologic compression or can be secondary to a local mass effect from a tumor in the sacrococcygeal region of the spine, as occurs in chordomas. Systemic or constitutional symptoms tend to be more common with malignant or metastatic disease than with benign lesions.



Laboratory Studies

For these patients, workup should include a complete blood count (CBC) and differential, a basic serum chemistry profile, erythrocyte sedimentation rate (ESR), or C-reactive protein (CRP) to help distinguish between neoplastic and infectious processes. Elevations in serum calcium or alkaline phosphatase (ALP) also can provide evidence for neoplastic bone processes. Specific studies, such as serum electrophoresis or urine electrophoresis, also can be performed to evaluate the likelihood of multiple myeloma or plasmacytoma.

Imaging Studies

Imaging studies for the workup of spine tumors include plain radiography, computed tomography (CT), magnetic resonance imaging (MRI), and technetium bone scanning. [456]

The first-line imaging study should be plain radiography to evaluate the trabecular architecture of the spine. Anteroposterior (AP), lateral, and oblique views may be required. These studies should be evaluated with respect to both what the tumor is doing to the bone and, conversely, what the bone is doing to the tumor. The blastic or lytic nature of the lesion should be noted. The general location of the lesion within the bone, the integrity of the cortex, and the presence of fractures or soft-tissue masses are important findings (see the images below).

Spinal tumors. Coned-down view of hemangioma in thSpinal tumors. Coned-down view of hemangioma in thoracic spine.
Spinal tumors. Axial CT scan of hemangioma in lumbSpinal tumors. Axial CT scan of hemangioma in lumbar vertebra.

Biopsy

The ultimate way of making the diagnosis and ascertaining the specific tumor type is to perform a biopsy of the spine lesion after all radiographic studies have been completed. Biopsies can be performed with open technique or percutaneous image-guided [789 technique. Percutaneous needle biopsies may not supply adequate tissue for the diagnosis of a primary tumor of the spine.

The basic principles of biopsy technique also apply to tumors of the spine. The surgeon performing the biopsy should take the most direct route to the tumor, with the least potential to contaminate adjacent compartments. The biopsy tract should be placed in line with the future incision site for surgical resection of the tumor, so that the biopsy tract can be excised with the specimen en bloc. (See the image below.)

Spinal tumors. Photograph of patient's back at timSpinal tumors. Photograph of patient's back at time of surgery, exhibiting course of definitive incision to excise chondrosarcoma en bloc with previous biopsy tract included with resection.

Meticulous hemostasis must be obtained, and a drain must be placed to prevent hematoma formation, which can dissect the soft-tissue planes and contaminate adjacent compartments. The drain should exit the skin in line with the incision so that it, too, can be excised with the final specimen.

Histologic Findings

The histologic findings vary according to the tumor type, as described above. The following list revisits the primary tissue types associated with some of the tumors of the spine:

  • Bone-producing tumors
  • Cartilage-producing tumors
  • Lymphoproliferative tumors
  • Tumors of notochordal origin
  • Round cell tumors

Bone-producing tumors of the spine include the following (see the images below):

  • Osteoid osteoma - Benign and locally self-limited
  • Osteoblastoma - Benign but locally expansile and aggressive
  • Osteosarcoma - Malignant spindle cell lesion that produces osteoid
Spinal tumors. Aneurysmal bone cyst histology. Spinal tumors. Aneurysmal bone cyst histology.
Spinal tumors. Histology of osteoblastoma at low mSpinal tumors. Histology of osteoblastoma at low magnification.
Spinal tumors. Higher magnification of osteoblastoSpinal tumors. Higher magnification of osteoblastoma.

Cartilage-producing tumors of the spine include the following:

  • Osteochondroma - Benign lesion with cartilaginous cap as described above
  • Chondrosarcoma - Malignant cartilage producing tumors that histologically demonstrate round cellular stroma in a chondroid matrix (see the image below)
Spinal tumors. Histology of chondrosarcoma at 40 tSpinal tumors. Histology of chondrosarcoma at 40 times magnification.

Lymphoproliferative tumors include the following:

  • Multiple myeloma and plasmacytoma - Derived from plasma cell dyscrasias, which histologically appear as sheets of plasma cells
  • Lymphoma - Associated with a large infiltrate of lymphoid cells

Chordoma is a tumor of notochordal origin that may be identified by the characteristic physaliferous cells (see the images below)

Spinal tumors. Chordoma histology. Spinal tumors. Chordoma histology.
Spinal tumors. Higher magnification of chordoma hiSpinal tumors. Higher magnification of chordoma histology demonstrates characteristic physaliferous cells.

Ewing sarcoma is a malignant round cell tumor of childhood that is associated with large sheets of homogenous small, round, blue cells.


Approach Considerations

The relevant anatomy discussed previously (see Anatomy) is frequently the limiting factor in determining contraindications for surgical excision of spine tumors. The morbidity of the tumor, the tumor's malignant potential, and the patient's overall prognosis must be compared to the morbidity and potential mortality of radical resection of a tumor near the spinal cord, the aorta, or the heart.

The degree of associated blood loss and the overall health of the patient also must be taken into consideration in considering a resection. If the patient is known to have metastatic or systemic tumor involvement, this may be a contraindication for radical resection of a paraspinous tumor, which may render the patient paralyzed.

Weinstein and McLain [10 and Boriani et al [11 developed a descriptive staging system for spine tumors based on the principles of the Enneking staging system for primary bone tumors of the extremities. In this staging system, the transverse extension of the vertebral tumor is described with reference to 12 radiating zones (numbered 1-12 in clockwise order) and five concentric layers (A to E) from the paravertebral extraosseous compartments to the dural involvement. The longitudinal extent of the tumor is recorded according to the levels involved.

Based on an understanding of the biologic behavior of the tumor, the oncologic staging aids the surgeon in deciding what surgical margin provides the best chance for complete tumor resection and possible cure. This system is complex and sometimes difficult to apply clinically.

Primary Benign Spinal Tumors

The Enneking classification of benign lesions applies to benign spine tumors, as follows:

  • Stage 1 - Latent
  • Stage 2 - Active
  • Stage 3 - Aggressive

Stage 1 lesions are usually asymptomatic and are discovered incidentally. Stage 2 lesions usually present with symptoms; most commonly, pain is in the area of the lesion. Stage 3 lesions are locally aggressive and can actually metastasize. [12]

Enostosis

Also termed a bone island, enostosis is a mass of calcified medullary defects of lamellar compact bone with haversian systems found within the cancellous portion of the bone. It occurs most frequently in the thoracic and lumbar spine, usually between T1 and T7 and between L1 and L2. Enostosis is one of the most common lesions to involve the spine.

Enostoses are usually stage 1 lesions and are discovered incidentally. Most remain stable, but some may slowly increase in size. Resnik et al determined the incidence of enostosis to be approximately 14% in cadavers. [13]

Radiographically, enostoses are circular or oblong osteoblastic lesions with a spiculated margin, which gives it the appearance of thorny periphery. An abrupt transition from normal to the sclerotic bone is exhibited on the radiograph. Bone scan findings are usually normal, and magnetic resonance imaging (MRI) demonstrates low signal intensity with normal surrounding intensity.

Enostosis sometimes can be confused with osteoblastic metastatic disease. Enostosis can be differentiated by lack of activity on bone scan, by the normal appearance of adjacent bone, by its thorny margins, and by lack of a primary tumor for metastasis. If the enostosis exhibits an increase in diameter of greater than 25% in 6 months, a biopsy should be performed.

Osteoid osteoma

Osteoid osteomas usually present in children aged 10-20 years, with a male predominance. They involve the axial skeleton only 10% of the time. In the spine, 59% of osteoid osteomas are found in the lumbar region, 27% in the cervical region, 12% in the thoracic region, and 2% in the sacral region. [1415]

Osteoid osteomas are usually stage 2 lesions and are actively symptomatic. They can result in painful scoliosis, radicular pain, gait disturbances secondary to pain and splinting, and muscular atrophy. Symptoms usually are relieved or ameliorated by administration of nonsteroidal anti-inflammatory drugs (NSAIDs) or salicylates. In the spine, osteoid osteomas occur 75% of the time in the posterior elements (pedicles, facets, or laminae). Osteoid osteomas occur 7% of the time in the vertebral body and 18% of the time in the transverse and spinous processes.

On plain radiography, osteoid osteomas appear as a round or oval radiolucent nidus, with a surrounding rim of sclerotic bone. An area of central calcification may be present, but this classic appearance may be obscured by complex spinal architecture. Bone scan shows marked increased uptake by the nidus, and a double intensity pattern may exist. Computed tomography (CT) is the criterion standard for radiologic diagnosis. The nidus is a well-defined area of low attenuation with or without central calcification surrounded by an area of sclerosis. (See the image below.)

Spinal tumors. Axial CT scan of thoracic vertebra,Spinal tumors. Axial CT scan of thoracic vertebra, which demonstrates nidus of osteoid osteoma in posterior elements.

The nidus is usually smaller than 1.5-2.0 cm, composed of microscopic well-organized trabecular bone with vascular fibrous connective tissue stroma surrounded by reactive cortical bone.

Treatment is accomplished by resection of the nidus via an open surgical approach or by percutaneous CT-guided resection. Percutaneous radiofrequency ablation (RFA) of the nidus has been performed with acceptable results. [16]

Osteoblastoma

Histologically similar in appearance to osteoid osteoma, osteoblastoma is behaviorally very different. [17 Demographically, it occurs in young patients in the second or third decade of life. A 2:1 male-to-female predominance exists. The lesion is distributed equally in the cervical, thoracic, and lumbar segments of the spine. The posterior elements are involved in 55% of cases, but the tumor can extend to the vertebral body in 42% of cases.

Patients typically complain of dull localized pain and paresthesias, as well as paraparesis and, if the tumor is large enough and encroaching on the spinal cord, paralysis.

Osteoblastomas are expansile lesions with multiple small calcifications and a peripheral scalloped and sclerotic rim. In more aggressive lesions, osseous expansion, bone destruction, infiltration of the surrounding tissue, and intermixed matrix calcification are present. Some 50% of osteoblastomas are radiolucent, and 20% are osteoblastic.

Marked radionucleotide uptake is exhibited on bone scan. CT demonstrates areas of mineralization, expansile bone remodeling, and sclerosis or a thin osseous shell at its margins. MRI is nonspecific but is the criterion standard for assessing the effect of the tumor on the cord and surrounding tissues.

Spinal tumors. Lateral cervical spine x-ray demonsSpinal tumors. Lateral cervical spine x-ray demonstrating osteoblastoma in posterior elements of C3 and C4.
Spinal tumors. MRI of osteoblastoma in posterior eSpinal tumors. MRI of osteoblastoma in posterior elements of C3 and C4 seen on previous x-ray image.

Osteoblastomas are typically larger than 2.0 cm in diameter with histologic features of interconnecting trabecular bone and fibrovascular stroma similar to, but not as well organized as, osteoid osteoma. They can have an aneurysmal bone cyst component in 10-15% of cases.

Wide local resection is the treatment of choice whenever possible. This sometimes is limited by the proximity of vital vessels or neural tissue in the spine. A 10-20% recurrence rate exists for conventional osteoblastomas. Aggressive osteoblastomas have a recurrence rate of approximately 50% if wide margins are not attained. These tumors are not radiosensitive.

Aneurysmal bone cysts

Aneurysmal bone cysts (ABCs) typically affect young patients, with 80% occurring in people younger than 20 years. The spine is involved 12-30% of the time. The thoracic spine is affected most commonly, followed by the lumbar and cervical spines. Sacral involvement is rare. [18]

ABCs of the spine usually present as expansile areas of bone remodeling in the posterior elements. Extension into the vertebral body can occur 75% of the time. The lesion may have a thin outer periosteal rim of bone, and septations within the mass may be apparent. The mass may extend into adjacent vertebrae, discs, ribs, and paravertebral soft tissues.

The bone scan exhibits peripheral increased uptake with a central "cold area" creating a donut sign. If angiography is performed, the mass is found to be hypervascular 75% of the time. CT and MRI are used to confirm the cystic nature of the lesion as well as the tumor extension into surrounding tissues and the tumor's relationship to the spinal canal. Single or multiple fluid/fluid levels sometimes can be visualized on MRI. MRI with gadolinium demonstrates enhancement of the periosteal rim and septations and not the cystic spaces.

ABCs are characteristically multiloculated blood-filled spaces that are not lined by endothelium. They are not vascular channels. Primary ABCs are believed to result from microtrauma to the bone with local circulatory disturbance. Other underlying neoplasms, such as giant cell tumors (GCTs), osteoblastomas, chondroblastomas, or osteosarcomas, produce secondary ABCs. These other neoplasms produce venous obstruction and possible arteriovenous malformations and set the stage for ABC formation. Most ABCs are considered primary (65-95%).

Because of the locally aggressive behavior of spinal ABCs, their treatment can be problematic. The severe morbidity that can be associated with complete resection is caused generally by danger to surrounding vascular or neural elements. ABCs can have a recurrence rate of 20-30% or higher, depending on the degree of resection. Preoperative embolization therapy and radiation may help shrink the tumor's size and decrease the amount of intraoperative blood loss associated with resection.

Osteochondroma

Osteochondromas make up 4% of all solitary spine tumors. [19 They also are commonly referred to as exostosis. Spinal lesions are encountered in 7-9% of patients with multiple hereditary exostoses (MHE). Osteochondromas occur in patients aged 20-30 years. Patients with MHE tend to develop the osteochondroma at a younger age; they also tend to experience neurologic deficits and myelopathy more frequently (77% of the time) than the patient with solitary osteochondroma (34%). A male predominance exists.

Osteochondromas are more common in the cervical spine, especially at C2. The posterior elements usually are involved. The lesions are believed to arise secondary to trapping of the physeal cartilage outside the growth plate during skeletal development.

Making the diagnosis of osteochondroma in the spine on plain radiography can be difficult unless the lesion is large and protruding posteriorly from a spinous process. In fact, 15% of patients with osteochondromas of the spine have normal appearing x-rays. CT is the study of choice for detecting the exostosis and determining its relation to the surrounding soft tissue and spinal canal.

T1-weighted MRI reveals a central area of high signal intensity, which represents yellow marrow. This area has intermediate intensity on T2-weighted images. The cortex of the exostosis has low signal intensity. The hyaline cartilage cap of the exostosis is best evaluated with MRI and appears with low signal intensity on T1 and high intensity on T2. The cartilage cap should be less than 2 cm in adults. Lesions with cartilage caps greater than 2 cm should be suspected of malignant transformation to chondrosarcoma.

Qualitatively, the bone composing an osteochondroma is normal. Abnormal bone growth occurs at and as a result of the cartilage cap. A continuity of the lesion with the marrow and cortex of the underlying bone is present. The exostosis may be sessile or pedunculated.

Complete surgical resection is usually curative. Clinical symptoms improve in 89% of patients following removal of the exostosis. Incomplete resection can lead to recurrence of the lesion.

Giant cell tumor

Giant cell tumors of the spine account for only 7% of all GCTs in the body. The spine is the fourth most common site for the occurrence of GCTs. Most spinal GCTs occur in the sacrum, followed by the thoracic, cervical, and lumbar regions. GCTs are more common in women and occur in the third to fifth decades of life. They can increase dramatically in size during pregnancy secondary to hormonal influences. Symptoms include pain with radicular pattern. With neurologic impingement, weakness and sensory deficits also can be manifest.

Spinal GCTs are usually radiolucent and expansile lesions. They do not exhibit active matrix production. When present in the sacrum, these lesions are large with destruction of the sacral foraminal lines on plain x-rays. GCTs usually can involve both sides of the midline and can extend past the sacroiliac joints bilaterally. When present in sites proximal to the sacrum, they usually are found in the vertebral body.

The classic findings of GCT on technetium bone scanning include diffuse radionucleotide uptake with areas of central photopenia and increased peripheral uptake. Angiography illustrates that most GCTs are hypervascular lesions. CT demonstrates soft-tissue attenuation with well-defined margins and a thin rim of sclerotic bone. MRI exhibits characteristic heterogeneous signal intensity with low-to-intermediate intensity on both T1- and T2-weighted images.

The great majority of GCTs are benign; malignant GCTs occur in only 5% of cases. Malignant GCTs usually are related to previous irradiation in the vicinity of the tumor. Even though most GCTs are benign, the lesions are locally aggressive, and their size and location may not allow complete resection. Those that cannot be excised en bloc should be curetted. Radiation is reserved for surgically inaccessible tumors. Selective arterial embolization also can be used in the management of these tumors. Recurrence rates can be as high as 40-60%.

Primary Malignant Spinal Tumors

Treatment of primary malignant tumors of the spine has been summarized by Levine and Crandall. [20 For treatment of astrocytomas, a less common spinal tumor, see Minnehan et al. [21 For treatment of nonambulatory patients, see Kondo et al. [22 For a discussion of palliative surgery for metastatic thoracic and lumbar tumors, see Cho and Sung. [23]

Kaloostian et al conducted a review of the literature regarding treatment and outcomes of patients with metastatic disease or primary tumors of the spinal column. [24 They reported that en-bloc resection is the mainstay of treatment for malignant primary tumors of the spinal column, whereas intralesional resection is generally appropriate for benign primary tumors. Low-quality evidence supports the use of chemotherapy in select primary tumors. Radiation therapy is often used for incompletely resected or unresectable lesions.

According to this review, surgical considerations for the treatment of metastatic disease (see Metastatic Tumors in the Spine) are more nuanced and require consideration of patient performance status and the pathology of the primary tumor. [24 Treatment of metastatic and primary tumors of the spinal column requires a multidisciplinary approach.

Glennie et al carried out a systematic review with consensus expert opinion regarding optimal reconstructive approaches after en-bloc resection of primary osseous spinal tumors. [25 The reached the following conclusions:

  • Posterior reconstruction with at least two vertebral levels above and below is recommended
  • Cages should be employed for single-level defects
  • Structural bone graft, either alone or in combination with a cage, should be employed for spanning a defect greater than two vertebral bodies

The authors also noted that postoperative radiation therapy, if planned, may affect fusion strategy. [25]

Chondrosarcoma

Chondrosarcoma is the second most common nonlymphoproliferative tumor of the spine. Chondrosarcomas make up 7-12% of all spine tumors, and the spine is the primary site in 3-12% of all chondrosarcomas. Men are affected two to four times more frequently than women. The mean age of presentation is 45 years. The thoracic spine is the most common site, but chondrosarcomas can occur at all levels of the spine. The most common symptoms are pain, a palpable mass, and neurologic complaints in 45% of patients.

Plain radiographs of chondrosarcomas typically demonstrate bone destruction. The lesions may be apparent in the vertebral body 15% of the time, in the posterior elements 40% of the time, or in both 45% of the time. In 70% of patients, the characteristic chondroid matrix in the form of rings and arcs is apparent on x-ray. Cortical destruction with soft-tissue extension is best observed on CT or MRI. (See the images below.)

Spinal tumors. Coned-down view of lateral thoracicSpinal tumors. Coned-down view of lateral thoracic spine in patient with chondrosarcoma.
Spinal tumors. Axial CT scan at level of chondrosaSpinal tumors. Axial CT scan at level of chondrosarcoma seen on previous x-ray image.
Spinal tumors. T2-weighted MRI scan of chondrosarcSpinal tumors. T2-weighted MRI scan of chondrosarcoma in same patient.

Chondrosarcomas that arise from malignant transformation of osteochondromas are observed as a thickening of the cartilaginous cap. Involvement of the adjacent vertebral levels by extension through the disc is observed in 35% of all lesions. On CT or MRI, mineralization is usually apparent in the soft-tissue component of the lesion. The radionucleotide uptake by the lesion is intense and has a heterogeneous appearance on bone scan.

Chondrosarcomas are relatively low-grade lesions (grade I or II). Most lesions are primary chondrosarcomas rather than secondary chondrosarcomas arising from the malignant degeneration of osteochondromas, as previously noted. Chondrosarcomas have relatively sparse cartilaginous stroma with a surrounding pseudocapsule. Examination under higher magnification reveals atypical nuclei with several mitotic figures per high-powered field.

Surgical resection by vertebral corpectomy and strut bone grafting sometimes may be necessary for complete excision. Cure is possible when complete resection can be achieved; this is possible 25% of the time. If wide marginal resection cannot be achieved, the tumor recurrence results in death in 74% of cases. The mean survival for all patients with chondrosarcomas is 5.9 years according to Shives et al. [26]

Adjunctive treatment with radiation is controversial for these tumors. Chemotherapy is used sometimes to help decrease the size of the mass with high-grade chondrosarcomas and dedifferentiated chondrosarcomas. Metastases of chondrosarcoma depend on the grade of the primary chondrosarcoma. The lungs are the most frequent sites of metastasis.

Ewing sarcoma

Ewing sarcoma is the most common nonlymphoproliferative primary malignant tumor of the spine in children. Lesions of the spine make up 3-10% of all primary sites of Ewing sarcoma. Metastatic foci of Ewing sarcoma involving the spine are more common than primary lesions of the spine. Patients with Ewing sarcoma usually present between the ages of 10 and 20 years.

The most common site of occurrence in the spine is the sacrococcygeal region, followed by the lumbar and thoracic segments. Ewing sarcoma rarely occurs in the cervical spine. Lesions are centered primarily in the vertebral body but they can extend into the posterior elements. [27]

Plain radiographs reveal permeative bone lysis, osseous expansion, or sclerosis. Diffuse sclerosis is observed in 69% of spinal lesions and is associated with osteonecrosis. CT and MRI demonstrate osseous involvement as well as surrounding soft tissue involvement. However, MRI is nonspecific.

Tissue from a Ewing sarcoma is composed of sheets of small, round, blue cells divided by septa, scant cytoplasm, and abundant collagen. Areas of osteonecrosis are found in spinal lesions. These correspond to the sclerotic areas observed on plain x-rays, as discussed above. Genetically, patients with Ewing sarcoma are found to have an 11;12 chromosomal translocation.

Before the advent of chemotherapy, the survival rate for patients with Ewing sarcoma was dismal because of the inability to completely resect these lesions, especially in the axial skeleton.

Radiation and chemotherapy are the current mainstays of treatment of Ewing sarcoma in the spine, achieving almost 100% local control with an 86% long-term survival rate in patients with spinal Ewing nonsacral sarcomas. Sacral tumors have a 62% local control rate and only a 25% long-term survival rate because of the tendency for delayed clinical presentation and larger tumor size. The most important prognostic indicator for survival of Ewing sarcoma is the tumor's response to chemotherapy.

Osteosarcoma

Osteosarcomas of the spine are rare, making up only 0.6-3.2% of all osteosarcomas and only 5% of all primary malignant tumors of the spine. They typically present in patients in the fourth decade of life and have a male predominance. Osteosarcomas are found at all levels of the spine but are most common in the lumbosacral segments. Eccentric involvement of the vertebral body with extension into the posterior elements is common.

Patients often present with pain and a palpable mass. Neurologic symptoms, ranging from sensory deficits to paresis, are found in 70-80% of patients. Serum alkaline phosphatase may be elevated.

Plain radiographs of spinal osteosarcomas reveal a densely mineralized matrix, giving rise to the term ivory vertebrae. A loss of vertebral height often occurs, with sparing of the adjacent disc. Purely lytic lesions also have been described. CT and MRI are useful for evaluating the extent of bony and soft-tissue involvement. If a large amount of mineralized matrix is present, the lesion may appear with low signal intensity on all MRI sequences.

Most osteosarcomas are blastic lesions (osteoblastic, chondroblastic, or fibroblastic). Osteosarcomas can arise primarily or secondarily from an exposure to radiation. Secondary osteosarcomas can have a latency of up to 20 years. Spinal osteosarcomas also have been found in patients with Paget disease.

Surgical resection is the rule; however, resection of spine lesions is often incomplete due to the size and location of the tumor at the time of presentation. Adjuvant chemotherapy and radiation therapy often are employed with varying degrees of utility. Spinal osteosarcomas have a dismal prognosis, with deaths usually occurring within the first year of diagnosis. Only a few patients have been reported to survive longer than 2 years.

Chordoma

Luschka first described chordoma morphologically in 1856 in Virchow's laboratory. The discovery of the notochordal nature of the tumor and the coining of the term chordoma is credited to Ribbert in 1894.

Chordomas are uncommon, accounting for 2-4% of all primary malignant bone tumors with a prevalence of 0.51 per million. However, they are excluding lymphoproliferative tumors and metastases, the most common primary malignant tumor of the spine in the adult.

As Ribbert described, chordomas arise for the notochord remnant. The notochord normally evolves into the nucleus pulposus of the intervertebral discs. Nonneoplastic notochord vestiges also are found at the midline of the sphenooccipital synchondrosis and in the sacrococcygeal regions. The locations in which chordomas occur parallel these vestigial distributions.

Regarding chordoma prevalence, 30-35% occur in the sphenooccipital region, 50% in the sacrococcygeal region (especially S4-S5), and 15% occur in the other spinal segments.

Interestingly, chordomas have not been reported to arise from the intervertebral disks. Chordomas occur most commonly in patients aged 30-70 years, with a peak incidence in the fifth to sixth decades of life. Sphenooccipital lesions have equal sex distributions but sacrococcygeal lesions have a 3:1 male-to-female ratio.

Presentation of chordomas is often subtle, with a gradual onset of pain, numbness, motor weakness, and constipation or incontinence. Constipation is a uniform finding in most patients with sacrococcygeal lesions. Chordomas are typically slow-growing lesions and are often very large at the time of presentation.

On plain radiography, chordomas appear as a destructive lesion of a vertebral body in the midline, with a large associated soft-tissue mass. In sacrococcygeal lesions, osseous expansion is frequent and may extend across the sacroiliac joints. Mineralization within the tumor may be observed on the plain radiographs of 50-70% of sacrococcygeal lesions. The mineralization is amorphous and predominates in the periphery of the lesion.

Lesions in spinal segments above the sacrum are less expansile and demonstrate evidence of calcification in only 30% of cases. They may have areas of sclerosis in 43-62% of cases. The intervertebral disks above or below a chordoma may be involved and narrowed in a manner that simulates infection. The lesion can make its way through the intervertebral disk to infiltrate an adjacent level. This occurs in approximately 11-14% of cases.

CT demonstrates both osseous and soft-tissue components of the tumor. Coronal and sagittal reconstructions of the CT scan are helpful in assessing neural foraminal and sacroiliac joint involvement. MRI is an important adjunct in the workup of chordomas. The lesions appear with low-to-intermediate signal intensity on T1 images and with very high signal intensity on T2 images, reflecting the high water content of chordomas. Enhancement occurs following intravenous (IV) contrast on both CT and MRI.

Chordomas are lobulated neoplasms, which usually are contained within a pseudocapsule. Histology of these lesions reveals long cords of physaliphorous cells. Physaliphorous cells are clear cells containing intracytoplasmic vacuoles with abundant intracellular and extracellular mucin. Sarcomatous chondroid, osteoid, or fibroid elements may be found within the chordoma.

Surgical resection is the rule. Adjuvant postoperative radiation therapy, proton beam therapy, and brachytherapy all have been used with varying results. The prognosis depends on whether the tumor can be resected completely. The location of the lesion and the size at presentation often necessitate incomplete resection. The treatment of sacral chordoma is an arduous clinical undertaking that requires a multidisciplinary approach and attention to detail from the outset.

Despite aggressive, well-planned surgical management and adherence to strict surveillance protocols, frequent recurrence and the late onset of metastatic disease are to be expected in a substantial proportion of patients, especially those with a large chordoma or one at a more cephalad level. Adequate surgical treatment results in substantial functional impairment and numerous complications; however, it does offer the possibility of long-term disease-free survival. [28]

Persons with sacrococcygeal tumors often have improved survival because the surrounding structures are relatively more expendable and allow a more complete resection. Persons with sacrococcygeal lesions typically have 8-10 years survival, as opposed to 4-5 years survival for persons with chordomas in other spinal sites. Death usually is related to local recurrence and invasion rather than metastatic disease. Chordomas can metastasize. The most common sites of metastases are the liver, lungs, regional lymph nodes, peritoneum, skin, and heart.

Multiple myeloma

Multiple myeloma is a systemic disease that affects middle-aged people and is characterized by areas of local bone destruction. Multiple myeloma is the most common primary malignancy of bone and the spine. The underlying cell line is the malignant plasma cell, which produces abnormal quantities of immunoglobulins.

The presentation of patients with myeloma is similar to that of other spine tumor patients. Patients complain of pain that may be worse at night. The laboratory workup for these patients should include a complete blood count (CBC) with differential looking for anemia and thrombocytopenia, an elevation of the erythrocyte sedimentation rate (ESR), and a decrease in the serum albumin with increased total serum protein. The abnormal production of immunoglobulins can be detected on serum or urine electrophoresis and can be used to confirm the diagnosis.

Radiographically, skeletal survey is used to screen for lesions that can occur throughout the skeleton. Bone scans have a high false-negative rate and are not optimal studies for the evaluation of myeloma. Once a lesion is detected in the spine, CT, MRI, or both should be performed to assess the destruction of the vertebrae and the effect of this destruction on the surrounding neurologic and paraspinous tissues.

Multiple myelomas are generally sensitive to radiation therapy and chemotherapy. Surgery for stabilization is indicated in myelomas of the spine when destruction of the vertebral body exists to such an extent that collapse and possible kyphosis with canal compromise could result.

Prophylactic posterior stabilization can be carried out with segmental instrumentation in cases prior to fracture. Anterior strut grafting or cage reconstruction may be necessary once fracture and collapse have occurred. Adjuvant radiation therapy may be used postoperatively once healing of the surgical site has been obtained.

Solitary plasmacytoma

Akin to multiple myeloma as a descendent of plasma cell malignancies, plasmacytoma is a solitary lesion that usually affects the vertebral body. Plasmacytomas generally affect younger patients than multiple myeloma and are associated with a better prognosis. Plasmacytomas eventually can evolve into multiple myeloma; thus, patients should be monitored for more than 20 years following the original diagnosis of plasmacytoma.

The diagnosis is made by biopsy of the lesion, and treatment includes radiation and bracing except in persons with pathologic or impending pathologic fractures. In these individuals, surgical resection and stabilization should be carried out with postoperative adjuvant radiation therapy once 6-8 weeks of postoperative healing has occurred. Patients have greater than 60% 5-year survival rates.

Metastatic Tumors in the Spine

The tumors that most commonly metastasize to the spine are as follows:

Tatsui et al found that patients with prostate cancer had the highest rate of metastases to the spine. [29 They also found that lung cancer was the most common primary lesion in patients whose spinal metastases were detected before the diagnosis of primary lesions.

The time from diagnosis of the primary lesion to detection of the spinal metastasis was shown to be shortest in patients with lung cancer and longest in those with breast cancer. Patients with metastases from breast cancer or prostate cancer had the highest 1-year survival rate, whereas patients with metastases from lung or gastric cancer had the lowest 1-year survival rates.

Various prognostic scoring systems have been developed to assess candidacy for surgery in patients with vertebral metastases, including the  Tokuhashi, Tomita, Bauer, Oswestry, Van der Linden, Rades, and Katagiri systems. The Spinal Instability Neoplastic Score (SINS) differs from others in that it looks for impending spinal instability. A review by Cassidy et al found that the Bauer and Oswestry systems predicted the prognosis most accurately and noted that the SINS showed good reliability for predicting instability among surgeons and oncologists. [30]

Stereotactic body radiotherapy (SBRT) is a newer approach to treating spinal metastases that has been described as having potential advantages over external beam radiotherapy. [31323334 

Advances in the molecular understanding of metastatic spinal tumors are likely to bring about substantial changes in management paradigms. [3536 Through molecular characterization, critical information can be obtained that can be used for making the initial diagnosis, determining the optimal treatment approach, evaluating the efficacy of treatment, and monitoring for recurrence, as well as for predicting complications, clinical outcome, and overall survival.

Complications

Complications associated with spinal tumors can be divided into the following two groups:

  • Complications associated with the tumor, its recurrences, or its metastases - Neurologic complications include radicular pain or focal weakness from impingement on a nerve root [37 and complete or incomplete paraplegia from direct pressure on the spinal cord
  • Complications associated with surgical, radiation, or chemotherapeutic treatment of the tumors - Complications that result from the treatment modality employed may be related to structures sacrificed during the surgical resection to obtain clear margins, structures in the path of radiation therapy, or the systemic effects of chemotherapy [38]

Fan et al conducted a study to analyze complications following posterior vertebral column resection in patients with spinal tumors. [39 A total of 36 complications were reported, and the following associations were noted:

  • Transient late tracheal extubation was associated with higher intraoperative bleeding volume and lower preoperative forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV 1)
  • Subsidence in the replaced spinal segment was associated with increased duration of surgery, higher intraoperative bleeding volume, and higher total blood transfusion volume
  • Thrombocytopenia was associated with increased duration of surgery and higher total blood transfusion volume

The majority of the complications were minor and did not affect patient recovery. [39 The investigators concluded that active preventive measures are necessary to reduce the incidence of major complications.