Spine Infections

Infections of the spine, although rare, are extremely devastating and, if not properly treated, can lead to spinal instability, neurological damage including paraplegia, and death. Spinal infections involving the vertebrae are called vertebral osteomyelitis. Infection of the disc is called discitis; Infection with pus within the spinal canal is called an epidural abscess. Often, patients present with only one or two of these clinical conditions, but some patients have all three of these entities and are often extremely ill. Spinal infections can be caused by bacterial infection, fungus, or tuberculosis. The incidence of pyogenic (bacterial) vertebral osteomyelitis, which is the most common form, is reported as 1 in 250,000 and is most common in the thoracolumbar spine region.

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Reasons

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The most common cause of spine infections is the spread of another infection from another part of the body through the bloodstream. Urinary tract infections or wound infections are the most common source of spinal infection. Spinal infections are much more common in elderly patients, patients with significant medical problems (diabetes, etc.) and immunocompromised patients (transplant patients). Initially, the infection is characterized by decreased vascular flow.vertebral end platestarts near. Once it begins to spread, the entire vertebral end plate becomes infected; The infection then spreads to the disc and the endplates of the adjacent vertebrae. If the infection is left untreated, it gradually erodes a large portion of the bone, which can destabilize the spine and compromise neurological structures.

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Symptoms

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Back pain is the most common symptom of patients with thoracolumbar spine infections. Patients often have night pain that does not go away with rest or traditional measures, as well as unremitting pain. Patients will usually have back stiffness and range of motion. If the infection is advanced and causes neurological compression or irritation, patients may experience weakness or lethargy. In addition, patients may have structural symptoms such as low-grade fever, chills, night sweats, fatigue, malaise, and/or loss of appetite, among others.

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Physics Findings

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Physical findings are limited in patients with spinal infections. Patients may or may not have a fever. Patients may show tenderness and spasm with reduced lumbar range of motion. Neurological examination will usually be normal unless the spinal infection is advanced and does not cause neurological compression or irritation.

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Imaging studies

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A plain X-ray of the spine will show subtle signs of end plate erosion and destruction, but this is usually not apparent in the first 1-3 weeks of a pyogenic infection. The most sensitive imaging test for a spine infection is a gadolinium-containing magnetic resonance imaging test (MRI). An MRI test can also identify the severity and extent of the infection and whether it involves the spinal canal (epidural abscess). Spinal infections caused by tuberculosis show a different radiographic appearance than bacterial infections; tuberculosis infections primarily affect the vertebral body and usually do not affect the disc, while pyogenic vertebral osteomyelitis preferably destroys the end plate and intervertebral disc. 

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lab tests

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Laboratory tests are often used to diagnose spinal infections. A complete blood count (CBC) with a differential, a C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) is routinely requested when evaluating an infection. In most cases, patients will show a high white blood cell (WBC) count. Patients with spinal infections who do not have high WBC will almost always have abnormally high CRP and ESR tests. Serial laboratory tests may also be used to monitor whether the infection is being treated effectively with antibiotics. A PPD skin test should also be done to test for tuberculosis.

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Diagnosis

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Diagnosis of a spine infection is often delayed primarily because early signs and symptoms are unclear and clinicians do not initially suspect it. Patients with symptoms suggestive of infection or tumor, such as severe pain, night pain, fever, chills, night sweats, weight loss, should be evaluated appropriately with imaging and laboratory tests to confirm the diagnosis.

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Treatment options

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Treatment of thoracolumbar spine infection depends on the severity of the patient's symptoms and the severity of neurological compression and bone destruction. Patients are initially referred for fine needle aspiration (FNA) or closed bone biopsy and culture to identify the specific type of bacteria causing the infection. Patients in whom biopsy or aspiration has failed and the results are uncertain may be considered for open biopsy. Patients are usually treated with strong antibiotics for 4 to 8 weeks until the infection clears. Patients are usually indicated for surgical debridement if they have spinal instability, significant deformity, and/or neurological deficits. A paravertebral abscess or epidural abscess of any size that causes sepsis is usually an indication for immediate surgical intervention.