– Workup

• White blood cell count (WBC) may be increased in these patients, although in many this value will be normal.

• Erythrocyte sedimentation rate (ESR) is more sensitive but is relatively nonspecific for infection.

• C-reactive protein (CRP) is elevated in at least 90% of patients with spinal infections and is a reliable indicator of the disease course because it tends to rise acutely with the onset of an infection but returns to baseline rapidly as it resolves.

• Blood cultures may be useful because they have been shown to reveal the causative pathogen in up to 58% of hematogenous spinal infections.

• Urinalysis and culture with sensitivities should also be obtained to rule out an infection of the urinary tract, which may spread to the spine.

– Neuroimaging

• Plain radiographs are the standard form of initial imaging study for suspected cases of spinal infections and will frequently exhibit abnormalities (89% of cases).

• Computed tomography (CT) may display early pathologic changes within the spinal column as well as any fluid collections in the surrounding soft tissues.

• Magnetic resonance imaging (MRI) is the ideal diagnostic modality for identifying pyogenic discitis.

Edema and fluid may be evident within the discs and adjacent tissues on T2-weighted images.

Addition of gadolinium contrast can enhance the visualization of paraspinal and epidural enhancement suggestive of active infection.

• Technetium-99m/gallium-76 citrate bone scans or indium-111 tagged WBC studies are extremely sensitive for diagnosing spinal infection but are less specific.

– Treatment

• First-line treatment for pyogenic infections is administration of broad-spectrum intravenous (IV) antibiotics for at least 6 to 8 weeks until culture-specific regimens may be initiated.

Identify the pathogen with biopsy, blood, or tissue cultures prior to treatment initiation.

• Immobilization may be beneficial for reducing pain and stabilizing the spine.

• The goals of surgery include debridement of the infected tissue, decompression of the neural structures, and stabilization of the spine.

– Surgical pearls

• Sputum should be acquired for acid-fast bacilli (AFB) and fungal cultures.

– Neuroimaging

• Individuals suspected of having tuberculous infections should be assessed with a chest x-ray, which may demonstrate pulmonary disease as well as any extensive bony lesions or focal kyphosis.

• MRI is the imaging modality of choice and will often show destruction of the vertebral bodies with relative sparing of the intervertebral discs.

– Treatment

• Pathogen-directed antimicrobial therapy

Six to 12 months of a multidrug treatment, including isoniazid, rifampin, pyrazinamide, and streptomycin or ethambutol is the standard regimen for Mycobacterium tuberculosis.

Antifungals such as amphotericin B or ketoconazole are employed for culture-documented fungal disease.

Surgical intervention is not routinely performed for these infections unless there is a failure of pharmacotherapy, progression of deformity, instability, or neurologic decline.

– Surgical pearls

• These types of infections may bring about considerable destruction of the vertebral bodies, which may require reconstruction of the anterior column.

• Supplementary posterior fixation may also be indicated to minimize the risk of developing a postoperative deformity.

• Colonization of metallic implants rarely occurs with granulomatous infections.

Avoid stainless steel implants

Postoperative imaging with CT and MRI is easier with titanium implants (decreased artifact compared with stainless steel implants).

IV. Epidural Infections

– Background

• Abscesses most often arise from adjacent vertebral osteomyelitis/discitis but may also develop from hematogenous extension or direct inoculation from spinal procedures.

• Staphylococcus aureus is the most common pathologic organism.

– Signs, symptoms, and physical examination

• Patients regularly complain of axial pain but symptoms may be more subtle with less virulent organisms.

• Larger lesions may compress the neural elements and give rise to neurologic deficits.

– Workup

• Standard infection laboratories (e.g., WBC, ESR, and CRP) with blood cultures

• Identification of a specific pathogen may require a needle or open biopsy to acquire tissue for culture.

– Neuroimaging

• MRI is the most sensitive and specific imaging study because it clearly demonstrates any fluid collection in the epidural space.

– Treatment

• Patients who are neurologically intact may be candidates for nonsurgical treatment consisting of long-term antibiotic therapy.

• Surgical decompression ± stabilization is generally indicated for individuals who have failed medical management or who present with neurologic deterioration.

– Surgical pearls

• Operative approach is largely influenced by the location of the infection.

• While a laminectomy may be sufficient to address posterior abscesses, an anterior procedure may also need to be performed in the setting of vertebral osteomyelitis or ventral abscess.

• Concomitant arthrodesis may be warranted in cases where spinal instability has been caused by the infection or any subsequent decompression.

• Postoperative SSI ordinarily arises following direct inoculation of the wound with normal skin flora.

– Signs, symptoms, and physical examination

• The typical SSI is clinically evident and associated with obvious erythema, edema, and drainage from the incision, although subfascial lesions may yield few external signs of infection.

• Patients may or may not complain of pain or exhibit constitutional symptoms.

– Workup

• WBC, ESR, and CRP are frequently elevated and may be used as serial markers to confirm the resolution of a SSI.

• Wound cultures are essential for directing antimicrobial therapy.

Sampling of deep wound collections is preferable since superficial drainage is prone to contamination with skin flora.

Intraoperative cultures represent the ideal method for identifying the causative organism.

– Neuroimaging

• CT may reveal pathologic changes such as an abscess or hematoma, but these findings may be difficult to differentiate from nonspecific postoperative changes.

• MRI is ideal for identifying fluid collections, but in many cases there will be an increased signal on T2-weighted images and contrast enhancement in the surgical field regardless of whether a SSI is present.

– Treatment

• Prophylactic antibiotics administered 60 minutes before a spinal procedure have been shown to reduce the incidence of SSI by up to 60%.

• Additional doses of intraoperative antiobiotics should be dispensed for prolonged surgical procedures with significant blood loss or gross contamination.

• Definitive therapy for established SSI is open irrigation and debridement.

• IV antibiotics are typically continued for a minimum of 6 weeks, at which time patients may be switched over to oral medications depending on clinical course and laboratory profile.

– Surgical pearls

• Metallic hardware is frequently left in place to maintain stability, but any loose bone graft should be removed to prevent the formation of a nidus of bacteria.

• Following open irrigation and debridement, the wound may be closed primarily over drains, covered with a vacuum dressing, or left open.