Acute spinal cord compression is sometimes subtle, but is always a devastating disorder. The good news is that it is a potentially treatable condition. Patients rarely know that spinal cord compression is the cause of their symptoms, but they often find themselves in the ED because they certainly know something is wrong, usually trauma, tumor, epidural abscess, or epidural hematoma, which are the most common causes of spinal cord compression.
Spinal cord compression used to be a relatively uncommon presentation in the ED, but it is now seen on a regular basis. It is a common medical-legal dilemma for clinicians. The increased incidence is due to longer-term survival from initial cancer treatment, the use of intravenous drugs and associated spinal infection, and spontaneous epidural hematoma associated with a variety of anticoagulants and antiplatelet therapies. One always considers potential spinal cord injury in patients with trauma, particularly those with cervical spine injuries, but symptoms associated with cancer, anticoagulants, and infection make this diagnosis less apparent. A plethora of other conditions can also produce similar initial symptoms.
Acute Spinal Cord Compression
Ropper AE, Ropper AH
N Engl J Med
This review article by two neurosurgeons is well worth reading. They pointed out that the cardinal features of acute spinal cord compression are relatively symmetric paralysis of the limbs, urinary retention or incontinence, and a loss of sensation below a circumferential boundary, referred to as a sensory level. Localized back and neck pain are additional characteristics of most types of acute cord compression, but variations and partial presentations are common. Extremities that are without reflexes or movement, accompanied by systemic hypotension, are common findings of spinal shock, and are characteristic of trauma-induced cord compression. This pathology would rarely be missed, even on an initial evaluation.
The spinal cord ends near the L1-L2 level where it transitions to spinal roots that make up the cauda equina. Compression of the cauda equina in the lumbar spine likewise causes paralysis, sensory loss, and early incontinence. A careful neurological examination usually pinpoints the area of spinal cord compression, but in the era of CT/MRI omnipresence, the physical exam is often shortchanged.
Compete loss of neurological function below a specific level often results in permanent paralysis. Even slight preservation of sensation in the perineum, however, is associated with a better neurological outcome. In the case of trauma, surgical efforts are focused on establishing spinal stability so that the cord will not be subjected to subluxation or cord compression when the patient is mobile. These authors believe that spinal instability is unlikely in the absence of cervical pain or tenderness in trauma patients with full range of motion of the neck. Spinal cord compression is often confusing or questionable if the patient is intoxicated, drugged, has additional injuries, or is unable to adequately or accurately report symptoms.
CT exam is preferred for initial imaging in patients with neurological abnormalities, and suggests traumatic cord compression because of its sensitivity in detecting fractures and vertebral subluxation. Ligamentous injury, disc herniations, or edema and hemorrhage in the spinal cord can be more readily identified with MRI. These authors believe that an MRI is the study of choice in trauma patients who are unable to provide evidence that the discs and ligaments are undamaged. Major fractures that cause misalignment of the spine can be seen with standard radiographs, but these days CT scan is usually the first selected investigative tool.
Most institutions have abandoned the use of high-dose of glucocorticoids for cord injuries in spinal trauma, though these were previously a mainstay of treatment. Clinical guidelines include the rapid reversal of hypotension with intravenous vasopressors if the blood pressure is below 85 to 90 systolic. This apparently lessens spinal cord injury from persistent hypotension.
Spinal cord compression also occurs when cancer metastases extend from bones of the spine into the epidural space. Aching back pain and tenderness over a percussed area may precede abnormal neurological features by several weeks. The most frequent cancers causing spinal metastasis and spinal cord compression are lung, breast, prostate, thyroid, kidney, and non-Hodgkin's lymphoma. The most common area for the cord to be compressed with cancer is in the thoracic spine. Lesions may be multiple, so MRI evaluation of the entire spine should be obtained even though symptoms appear to be located in one section. Gadolinium is added as a contrast agent to the MRI, but most tumors can be detected without the contrast agent, so do not withhold the plain MRI in a patient with risk factors for dye sensitivity.
Glucocorticoids are indicated to reduce neurological impairment and spinal pain in the case of cancer-induced spinal cord compression. The best dose of dexamethasone has not been established, and recommendations range from repeated 10 mg aliquots to an initial dose of 100 mg. Definitive treatment, such as surgery vs radiation or chemotherapy is guided by the extent of the cord compression and the type of cancer, and is in the hands of consultants.
Bacterial infections of the spinal epidural space (abscess) have a high rate of delayed diagnosis. The spinal cord is injured by mechanical compression and vasculitic infarctions from the infection. Fever and severe back pain are the main features of a spinal epidural abscess. Often no primary infection is discovered. The most common bacteria isolated from spinal cord abscesses is Staphylococcus aureus, evenly distributed between methicillin-resistant and methicillin-sensitive organisms. Probably the most beneficial therapy is surgical evacuation of the infection by decompression laminectomy. Paralysis for more than 48 hours is a poor prognostic sign, and generally is not associated with recovery of spinal cord function.
Spinal epidural hematomas can cause cord compression, and are usually associated with back pain followed by weakness. MRI findings dictate therapy.
Comment: Specific treatment of acute spinal cord compression is usually delegated to the neurosurgeon or cancer specialist, but the diagnosis must first be suspected or made before the appropriate subspecialists can be consulted. A rather vexing problem in emergency medicine is the omnipresence of patients with back pain, those with cancer, and those with intravenous drug abuse. Back pain was often used as a way to obtain opioids from unsuspecting clinicians, but every IV drug abuser who complains of back pain should be looked at with a suspicious eye. Yes, they are drug-seekers, but they also get real medical problems.
Only one to two percent of patients with back pain have something other than musculoskeletal or disc pain. The vast majority of these patients will not have spinal compression or even serious pathology. The 34-year-old who has low (lumbar) back pain after lifting a heavy object at work is not of great concern. The IV drug abuser with thoracic back pain and a temperature of 100°F demands an all-out mobilization of resources in the ED.
The clinician should always be aware of potential badness with the spontaneous onset of thoracic back pain. Most patients will conjure up a reason for their back pain that can delay diagnosis. Lifting a refrigerator a week earlier and current back pain are not related, so beware of the patient's reasons for the symptoms.
The so-called red flags of back pain that mandate further attention include fever, incontinence, unexplained weight loss, cancer (often remote by years), long-term steroid use, IV drug use, intense localized pain, and inability to get into a comfortable position. Thoracic and abdominal aortic dissection and aneurysms are another cause that must be considered in patients with back pain unrelieved by rest. Suspecting potential spinal cord compression is easy if the patient has sensory loss, weakness, or incontinence.
Up to 80 percent of adults will have back pain at some time in their life. It is often recurrent and quite bothersome, but it is rarely a harbinger of serious medical illness. The difficult mandate of the emergency clinician is to separate those with chronic mechanical back pain from those with cancer, epidural abscess and hematoma, or osteomyelitis. Because one rarely works a shift without seeing someone with back pain, it's easy to get into a routine of a quick examination and an analgesic prescription.
The physical examination of a patient with back pain is neither complicated nor prolonged, and is directed toward ruling out the red flags and other worrisome scenarios or identifying specific neurological deficits. One should always do a rectal temperature in less-than-straightforward cases. Patients who have pain when they are immobile less often have a benign etiology. The abdomen should also be examined for a murmur or mass. The back should be carefully palpated and percussed over individual vertebral bodies. Isolating an area of point tenderness is uncommon with benign back pain. The extremities should be tested for sensation and motor strength. A rectal exam is not required for most cases of lower back pain, but it should be routine in those with any red flags, looking for rectal tone in particular. A CT is superior for evaluating bony details of the spine, but the preferred imaging modality for patients with straightforward, run-of-the-mill low back pain is an MRI.
Certain characteristics of back pain should alert the clinician. The first is constant pain or pain that does not vary with the use of medication or position. The spontaneous onset of a thoracic pain is unusual. The spinal canal is narrow in this region and an anatomical set-up for cord compression. The thoracic region is the most common area for cord-compressing metastatic disease, so the presence of thoracic pain is more worrisome than lumbar pain. Also night pain, particularly associated with lying down and non-weight-bearing, is suspicious.
A patient seeking opioids is a common scenario in the ED, and addicts are often good at relaying symptoms of a real or serious medical illness, coming up with slick reasons why their previous pain prescription was lost or didn't work, or saying their regular prescriber is on vacation. It's difficult for the emergency physician to remain objective when the third person with low back pain seeking opiates comes near the end of a shift. Most drug-seekers now know that back pain rarely gets them 120 oxycodone anymore.
Back pain is usually the first sign of cord compression, but motor and sensory findings are generally present in most patients at the time of diagnosis because these findings initiate a search for disease. Bowel and bladder dysfunctions are generally late findings. Localized vertebral tenderness is a sensitive but not specific finding for spinal infection, vertebral metastases, osteomyelitis, and compression fractures.
It is not common to examine the breast, lymph nodes, and prostate for patients with back pain, but is appropriate in those whose history strongly suggests potential malignancy. Most patients with back pain do not require laboratory testing, and specific blood tests are rarely helpful. An elevated WBC count can suggest infection, and an elevated erythrocyte sedimentation rate may suggest more than musculoskeletal back pain.
The value of standard radiographs in patients with nonspecific back pain is minimal. I do not suggest they be used routinely. A CT scan or MRI is more appropriate if one is really concerned about more than a musculoskeletal problem. Even sagacious clinicians will encounter a lot of negative CTs and MRIs. They are only tests, but tests that can be of immense importance if positive.
Red Flags for Acute Low Back Pain∗
- History of cancer (especially lung, breast, prostate, thyroid, or kidney), often distant by years and despite a seeming cure
- Unexplained weight loss
- Known immunosuppression
- Prolonged use of steroids
- Intravenous drug use
- Unexplained nontraumatic thoracic back pain
- Pain that is increased or unrelieved by rest
- Pain for more than six weeks
- Age under 18 or over 50
- Bowel incontinence
- Urinary retention (with overflow incontinence)
- Saddle anesthesia
- Poor anal sphincter tone
- Major motor weakness or sensory loss in lower extremities
- Specific vertebral localized tenderness, especially thoracic spine
∗These items are evaluated in patients with back pain, and if present, indicate further consideration or urgent workup in the ED.
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