Spinal infections

Spinal infections can be classified according to the anatomical location:

vertebral column, intervertebral space, spinal canal and adjacent soft tissues. The infection can be caused by a bacterium or fungal organism and can occur after surgery. Most postoperative infections occur between three days and three months after surgery. Vertebral osteomyelitis is the most common form of vertebral infection. It can develop from open spinal trauma, infections in surrounding areas and bacteria that spread to a vertebra. The intervertebral space infections involve the space between the adjacent vertebrae. Disc infections can be divided into three subcategories: hematogenous adults (spontaneous), children (discites) and postoperative. Spinal canal infections include epidural abscess, an infection that develops in the space around the dura mater. Subdural abscess is much rarer and affects the potential space between the dura mater and the arachnoid (the thin membrane between dura and pia mater). Parenchymal infections of the spinal cord (primary tissue) are called intramedullary abscesses. Adjoining soft tissue infections include cervical and thoracic paraspinal lesions and lumbar psoas abscesses. Soft tissue infections usually affect younger patients and are not often seen in the elderly.

Incidence and prevalence

Vertebral osteomyelitis affects about 26 170 to 65 400 people a year. Epidural abscesses are relatively rare and affect only 0.2 to 2 cases out of 10 000 hospitalizations. However, 5 to 18% of patients with vertebral osteomyelitis or disc space infection caused by contiguous spread will develop an epidural abscess. Some studies suggest that the incidence of infections of the spine is increasing. This peak could be related to the increased use of vascular devices and other forms of instruments and to an increase in intravenous drug abuse. About 30 to 70% of patients with vertebral osteomyelitis have no obvious previous infection. Epidural abscesses can occur at any age, but are more common in people 50 years of age and older. Although the treatment has improved considerably in recent years, the mortality rate by spinal infection is still estimated at 20%.

Risk factors

Medical: advanced age, intravenous drug use, infection with human immunodeficiency virus (HIV), long-term systemic use of steroids, diabetes mellitus, organ transplantation, malnutrition, cancer.


Surgical: long operations, significant blood loss, the use of instruments and multiple surgeries or surgical revisions on the same site. Infections occur in 1 to 4% of cases, despite the many preventive measures.

Symptoms

Persistent back pain and sensitivity to touch. This pain is aggravated by the movement and is not alleviate by rest, by the application of heat, or by taking painkillers (analgesics). Fever, the most obvious sign of infection, is often absent.

Diagnostic

A blood test and, for the radiological examination, a magnetic resonance imaging (MRI) with injection of contrast medium. The standard radiography does not generally bring any interesting diagnostic element because of the radiological delay (on average six weeks) but it keeps all its value for the follow-up. As for CT-scan and scintigraphy (Tc 99-MDP, gallium citrate or polynuclear labeled with iridium), their sensitivity and / or specificity is lower and the analysis of the epidural space is insufficient. or even absent according to the techniques. However, it is important to remember that there are no pathognomonic MRI signs of infectious spondylodiscitis and that a number of radiological differential diagnoses are discussed. The clinician has to isolate the germ before starting an antibiotic treatment, not only to confirm the diagnosis but also to adapt the antibiotic therapy. The search for a concomitant infectious focus is therefore essential and samples from all potential sites must be made. At least three blood cultures must be performed in order to optimize the sensitivity of the method. Note that these are more sensitive when they are performed during a febrile peak but their performance during pyogenic infection is still close to 50% even in the absence of fever. Finally, the search for the bacterium at the site of infection is sometimes the only way to isolate the causative germ. Biopsy puncture under radiological control is the simplest method but its sensitivity is not perfect and, in case of failure, it is important to resort to a surgical biopsy.

Treatments

Few data are available on the duration of antibiotherapy adapted to the germ. A recent retrospective study, however, indicates a significant increase in the recurrence rate when it is less than four weeks. A survey carried out in France also indicates a great variability of behaviors according to the centers, with recommendations of durations ranging between six and twelve weeks. In practice, it therefore seems difficult to define a general attitude and the duration of treatment should be adapted not only to the type of germ but also to the patient's field.


The goal of the corset is twofold. Firstly it has an analgesic effect and allows a faster mobilization of the patient, thus reducing the complications related to prolonged bed rest. Moreover, it is expected that it reduces the deformation in kyphosis which sometimes complicates the infectious episode. If the first objective is easily verifiable in clinical practice, no data is available to confirm the second.


The surgical procedure, which is reviewed is mainly discussed during infections with pyogenic germs complicated by recent neurological involvement and in the presence of epidural abscess.