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Objectives

The following module was designed to supplement medical students’ learning in the clinic. Please take the time to read through each module by clicking the headings below.

By the end of the tutorial, the following objectives should be addressed:

  1. Describe the anatomy of the spinal cord
  2. Describe the epidemiology of spinal cord compression
  3. Describe the possible causes of spinal cord compression
  4. Appreciate the pathophysiology underlying the development of spinal cord compression
  5. Describe the general sites of spinal cord compression localization
  6. Describe how spinal cord compression is classified
  7. Describe the common signs and symptoms of spinal cord compression
  8. Understand the general approach to diagnosis of spinal cord compression
  9. Understand the imaging techniques used in the investigation of spinal cord compression
  10. Describe the initial management of spinal cord compression
  11. Understand the important factors to consider when selecting definitive treatment for spinal cord compression
  12. Understand the management algorithm for spinal cord compression
  13. List key prognostic factors for the outcome of spinal cord compression
  14. Appreciate the role of the interdisciplinary team in the management of spinal cord compression

Introduction

Spinal Cord Compression (SCC) is an oncology emergency that occurs as a result of metastatic or spinal tumor growth that either directly or indirectly causes impingement of the spinal cord [1,2,3]. Complications include pain and potentially irreversible neurologic dysfunction that may severely impact patients’ functional ability and overall quality of life [1].

Anatomy Review

Surrounded by the thecal sac, the spinal cord lies in the vertebral foramina of the vertebral column, extending from the base of the skull to the boundary between the L1/L2 vertebra. Below that level, lumbar, sacral, and coccygeal spinal nerve roots reside in the lumbar cistern and are referred to collectively as the cauda equina. The spinal cord is divided into four longitudinal regions (cervical, thoracic, lumbar, and sacral cord) each comprised of multiple spinal cord segments. Exiting from the intervertebral foramina, each segment has two pairs of spinal nerve roots which mediate motor and sensory functions.[4]

Figure 1. Anatomy of the spinal cord Source: [7]

Epidemiology

Incidence

Results of a population-based study which reviewed incidence, management, and outcome of spinal cord compression (SCC) demonstrated an overall 2.5% cumulative probability of experiencing at least one episode of SCC in the five years preceding death from cancer. Cumulative probability ranged from 0.2% to 7.9% depending on the cancer site, with highest cumulative incidence seen in myeloma (7.9%), prostate (7.2%), nasopharynx (6.5%), and breast malignancies (5.5%). Median survival following the first episode of MSCC was 2.9 months. [5]

Other studies suggest incidence of SCC up to 6% based on autopsies and other reports. [2]

Causes

Spinal cord compression can arise from primary spinal tumors or any metastatic tumor with a tendency to spread to the vertebral column. [2]

Pathophysiology

Tumor metastases to the bony elements of the vertebral column accounts for 85-90% of SCC. [2]

Possible mechanisms of metastases include: [2]

  • Hematogenous arterial seeding of bone (likely the most common mechanism)
  • Shunting of abdominal venous flow to the epidural venous plexus by the Valsalva maneuver
  • Tumor accesses epidural space via the neural foramen

Expansion of the tumor within the spinal column interferes with epidural venous plexus flow, leading to vasogenic edema of white and gray matter, and if uncorrected, infarction eventually ensues. [2]

Localization within the Spine

80-90% of SCC are metastatic tumors localized in vertebral bodies, causing compression of the anterior/anterolateral aspects of the spinal cord, often yielding localized symptoms. [1,2]

‍Figure 2. Metastases to the vertebral body
Figure 3. Metastases to the vertebral body causing epidural compression 

10% of SCC are paraspinal masses that invade through the neural foramen and into the epidural space. [1,2]

‍Figure 4. Paraspinal mass invading through the neural foramen

Longitudinally, 60% of SCC are localized in the thoracic spine, 30% in the lumbosacral spine, and 10% in the cervical spine. [1,2]

Classification

Spinal cord compression (SCC) can be further classified as intramedullary SCC, leptomeningeal SCC, or extradural SCC depending on the tumor site [1].  Malignant extradural SCC occurs when the tumor invades the epidural space, compressing the thecal sac [1].

Figure 5. Cross-section of the vertebral column Adapted from [1,4]

Signs and Symptoms

Specific signs and symptoms of SCC vary depending on the level and extent of cord obstruction.  In general, the most common clinical features include:

Back Pain

The presenting symptom in 83-95% of patients is progressively severe back pain that usually precedes neurologic symptoms by weeks, often leading to delayed recognition and diagnosis of SCC. [2]Additional features of the back pain may yield clues as to the underlying pathophysiological mechanisms. For example: [2]

  • Pain worsens with recumbency – may be due to distension of the epidural venous plexus and/or diurnal variation of endogenous corticosteroids
  • Pain only present with movement – suggests spinal instability; may require surgical approach
  • Local pain – may be due to involvement of spinal cord, paravertebral soft tissue, or dural nerves
  • Radicular pain – more common in lumbosacral lesions

Motor Symptoms

60-85% of patients present with weakness that typically worsens, progressing to gait dysfunction and paralysis by the time of diagnosis [2].  The presentation of motor symptoms varies depending on the location of cord compression:

  • Upper motor neuron lesion findings caudal to level of spinal cord compression (ex. hyperreflexia, extensor plantar reflex) [1,2]
  • Lower motor neuron lesion findings at level of cauda equina compression (ex. hyporeflexia) [1,2]

Sensory Changes

While more seldomly observed than motor findings, sensory changes are nonetheless present in the most SCC patients. Common sensory symptoms include ascending numbness and paresthesias, with the sensory disturbance typically 1-5 levels caudal to the site of compression. [2]Involvement of cord regions rostral to the cauda equina typically exhibit sacral sparing, with cauda equina lesions exhibiting saddle sensory loss. [2]

Bladder & Bowel Dysfunction

Disruption of bladder and bowel function is a late manifestation of SCC observed in up to 50% of patients, with urinary retention being the most common, but rarely the only autonomic symptom. [2]

Diagnostic Approach

Back pain in the presence of neurologic findings has a wide array of etiologies and requires thorough investigation beginning with a history and physical examination.  The following sections will outline the most pertinent differential diagnosis, and appropriate clinical approach to investigating a cancer patient with suspected SCC.

Differential Diagnosis of Back Pain in Cancer Patients [2]

  • Musculoskeletal disease – benign causes of back pain (ex. muscle spasm, disk disease, and spinal stenosis)
  • Spinal epidural abscess – rare, but maintain higher suspicion in patients with history of IVDU, vertebral osteomyelitis, or hematogenous infection
  • Metastatic disease – metastatic disease may also manifest without compression of the spinal cord, leading to back pain
  • Radiation myelopathy – a rare complication of spinal cord irradiation usually occurring 9-15 months post-radiotherapy

History

Pain – characterize quality of pain, location, distribution (ex. radicular), exacerbating circumstances (ex. recumbency, movement, etc)

Associated neurological symptoms

  • Motor findings – degree of weakness, gait dysfunction
  • Sensory changes – numbness, paresthesias, distribution of symptoms
  • Autonomic dysfunction – bladder and bowel symptoms

Duration of symptoms

General health/ROS

Past medical history (back problems, surgical/medical history)

Physical Exam

Perform full physical examination, paying particular attention to the following areas:

Neurologic/MSK exam

  • Cranial nerves, strength, tone, reflexes, sensation, sphincter tone
  • Back examination, percussion, and tenderness

Examine area of past malignancy (ex. breast, lung, abdomen, etc)

Imaging

Diagnosis of SCC requires radiologic evidence that demonstrates extrinsic neoplastic compression of the thecal sac at level of clinical features [1,2]. Thorough imaging of the entire spinal cord, thecal sac, and epidural space is critical for expedient diagnosis, as well as detection of additional sites of disease which significantly impacts management planning, and prognostic determination [1,2].

Modalities used for radiologic confirmation include: [2]

  • MRI – preferred modality for initial evaluation of patient with suspected SCC; provides excellent visualization of thecal sac and surrounding soft tissue as well as bone.
  • CT Scan – highly time efficient modality indicated if MRI is unavailable or contraindicated
  • CT Myelography – this modality is infrequently used although it is comparable to MRI in terms of sensitivity and specificity; indications include laterally located lesions that are poorly visualized with MRI, and radiosurgery treatment planning
  • Other imaging modalities are available though none are preferred over MRI or myelography for initial evaluation of SCC

Management

Rapid diagnosis and treatment of SCC is critical in preventing progression of neurological sequelae [1,6]. The goals of treatment should be to improve or maintain highest quality of life possible (ex. pain relief, prevention of complications, and restoration of function) [1]. Decisions regarding treatment should consider: medical status, ambulatory status, structural factors, anticipated outcome, treatment goals, and patient preference [1].

Management of SCC begins with immediate glucocorticoid administration in almost all patients and concurrent symptomatic treatment, followed by definitive treatment (either surgery, radiation therapy, or systemic therapy). [1,6]

Initial Therapy

Glucocorticoids

Glucocorticoids should be an integral component of initial therapy in patients with neurological symptoms and/or thecal sac compression.  Select patients with normal neurologic function, and/or small epidural lesions may not require steroid therapy.  Despite the risk of significant side effects and the lack of evidence supporting the beneficial effects of glucocorticoids, especially at high doses, glucocorticoids continue to be a part of standard management. [6]

Definitive Treatment

Selecting the modality of definitive treatment requires the consideration of factors such as: [6]

  • The presence or absence of spinal instability,
  • The degree of spinal cord compression,
  • The radiosensitivity/chemosensitivity of the tumor

Depending on the patient’s clinical situation, definitive treatment can include: surgery, radiation therapy, or systemic therapy. Table 1 outlines several factors to consider when deciding between surgery and radiation therapy.

TABLE 1: SURGERY VS. RADIATION THERAPY FOR TREATMENT OF SCC

Surgery

Surgical treatment of SCC is considered in patients with spinal instability and radioresistant tumors that compress on the cord [6].  Treatment entails aggressive tumor resection, and if necessary, followed by spinal reconstruction/stabilization [6].  While surgery intuitively has the advantage of providing immediate functional and physiologic stability, uncontrolled studies have previously reported differing results in regards to surgery versus radiotherapy (RT) [1].  Recently, a 2005 randomized trial has demonstrated the benefit of aggressive tumor debulking followed by RT when compared to RT alone  in regaining and maintaining ambulation [6].  As higher rates of postoperative complications were observed in patients over the age of 65, patients who had prior treatment, and patients with paraparesis, care must be exercised when selecting surgical candidates [6].  Only patients with acceptable medical status and reasonable life expectancy should be offered the option of surgical resection as postoperative healing and rehabilitation may not be suitable for all patients [1,6].

Radiation Therapy (RT)

Radiation therapy is a well-established modality for the treatment of SCC particularly effective in pain reduction, recovery of functional status, and improvement of sphincter function [1].   Two radiation therapy techniques are utilized in the treatment of SCC: External Beam Radiation THerapy (EBRT), and Stereotactic Body Radiation Therapy (SBRT).

EXTERNAL BEAM RT (EBRT)

EBRT is indicated for patients who are considered unsuitable for surgery with relatively radiosensitive tumors (ex. breast, prostate, ovarian, SCLC, myeloma, lymphoma), and as subsequent treatment following surgical decompression.  Response to EBRT treatment is generally excellent for local tumor control and palliation of pain.  While typically well tolerated, irradiation to extensive spinal segments may lead to complications such as bone marrow suppression and gastrointestinal toxicity. [6]

STEREOTACTIC BODY RT (SBRT)

SBRT, also referred to as Stereotactic Radiosurgery, is a technique that delivers precise radiation to the tumor while reducing irradiation of the surrounding tissue. The targeted nature of SBRT allows the utilization of high dose radiation that would otherwise be intolerable to the spinal cord, which is a major limitation of EBRT. A further advantage of SBRT is its efficacy in pain reduction and local tumor control of relatively radioresistant neoplasms, which makes the technique an excellent choice in patients with radioresistant cancer. [6]

Systemic Therapy

Although most malignancies that cause SCC are chemoresistant, chemotherapy is a potential treatment option in patients with chemosensitive neoplasms.

Prognosis

The single most critical prognostic factor for the recovery of ambulation after treatment of SCC is the patient’s neurologic status prior to initiating management. [6]  Additional prognostic factors for the outcome of spinal cord compression are outlined in table 2.

TABLE 2: PROGNOSTIC FACTORS FOR SCC [1]

Summary

Malignant spinal cord compression is an oncology emergency and a common sequelae of cancer. Complications include pain and potentially irreversible neurologic dysfunction.

The most common presenting symptom is back pain followed by neurological symptoms, such as motor weakness, and sensory changes.

The most important steps in management of SCC relies on expedient diagnosis and treatment of SCC, which depends on the interdisciplinary cooperation of multiple specialties, including:

  • Radiology
  • Neurosurgery/orthopedic surgery
  • Radiation oncology
  • Medical oncology

Initial therapy for SCC should include the immediate administration of glucocorticoids

Definitive treatment options for SCC include surgical debulking, radiation therapy (EBRT or SBRT), and chemotherapy

Decisions regarding treatment should consider: medical status, ambulatory status, structural factors, anticipated outcome, treatment goals, and patient preference.

Virtual Patient Case

This case study was designed to supplement your knowledge on the workup of Spinal Cord Compression and test what you have learned after going through module. Use your mouse to click through the slides and answer each question in the text box provided.

Note: This case can be completed on an iPad. To do this download the (free) Articulate Mobile Player for the iPad by clicking here.

References

  1. Ingledew, P. Oncology emergencies for medical students, PowerPoint presentation, FVCC, Surrey.
  2. Schiff, D. Clinical features and diagnosis of neoplastic epidural spinal cord compression, including cauda equina syndrome. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on July 11, 2014).
  3. Canadian Cancer Society: Spinal cord compression. Available at http://www.cancer.ca/en/cancer-information/diagnosis-and-treatment/managing-side-effects/spinal-cord-compression/?region=on. Accessed July 11th, 2014.
  4. Eisen, A. Anatomy and localization of spinal cord disorders. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on July 11, 2014).
  5. Loblaw, DA, Laperriere NJ, Mackillop WJ. A population-based study of malignant spinal cord compression in Ontario. J. Clin. Oncol. 2003 Jun;15(4):211-17.
  6. Schiff D, Brown P, Shaffrey ME. Treatment and prognosis of neoplastic epidural spinal cord compression, including cauda equina syndrome. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on July 11, 2014).
  7. Drake RL, Vogl W, Michell AW. Gray’s Anatomy for Students 2nd Edition. Elsevier Inc.; 2009.

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