Mr. Shuaibu Dambatta | Consultant Neurosurgeon | Complex Spine Surgeon | +44 7940973565 | info@spine-neurosurgeon.co.uk

SPINAL INFECTION

Spinal infections can be classified by the anatomical location involved: the vertebral column, intervertebral disc space, the spinal canal and adjacent soft tissues. Infection may be caused by bacteria or fungal organisms 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 direct open spinal trauma, infections in surrounding areas and from bacteria that spreads to a vertebra from the blood.

Intervertebral disc space infections involve the space between adjacent vertebrae. Disc space infections can be divided into three subcategories: adult hematogenous (spontaneous), childhood (discitis) and postoperative.

Spinal canal infections include spinal epidural abscess, which is an infection that develops in the space around the dura (the tissue that surrounds the spinal cord and nerve root). Subdural abscess is far rarer and affects the potential space between the dura and arachnoid (the thin membrane of the spinal cord, between the dura mater and pia mater). Infections within the spinal cord parenchyma (primary tissue) are called intramedullary abscesses.

Adjacent soft-tissue infections include cervical and thoracic paraspinal lesions and lumbar psoas muscle abscesses. Soft-tissue infections generally affect younger patients and are not seen often in older people.

  • Vertebral osteomyelitis affects an estimated 26,170 to 65,400 people annually.
  • Epidural abscess is relatively rare, with 0.2 to 2 cases per every 10,000 hospital admissions. However, 5-18% 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 spinal infections is now increasing. This spike may be related to increased use of vascular devices and other forms of instrumentation and to a rise in intravenous drug abuse.
  • About 30-70% of patients with vertebral osteomyelitis have no obvious prior infection.
  • Epidural abscess can occur at any age, but is most prevalent in people age 50 and older.
  • Although treatment has improved greatly in recent years, the death rate from spinal infection is still an estimated 20%.

Risk factors for developing spinal infection include conditions that compromise the immune system, such as:

  • Advanced age
  • Intravenous drug use
  • Human immunodeficiency virus (HIV) infection
  • Long-term systemic usage of steroids
  • Diabetes mellitus
  • Organ transplantation
  • Malnutrition
  • Cancer

Surgical risk factors include surgeries of long duration, high blood loss, implantation of instrumentation and multiple, or revision, surgeries at the same site. Infections occur in 1-4% of surgical cases, despite numerous preventative measures that are followed.

Spinal infections can be caused by either a bacterial or a fungal infection in another part of the body that has been carried into the spine through the bloodstream. The most common source of spinal infections is a bacterium called staphylococcus aureus, followed by Escherichia coli.

Spinal infections may occur after a urological procedure, because the veins in the lower spine come up through the pelvis. The most common area of the spine affected is the lumbar region. Intravenous drug abusers are more prone to infections affecting the cervical region. Recent dental procedures increase the risk of spinal infections, as bacteria that may be introduced into the bloodstream during the procedure can travel to the spine.

Intervertebral disc space infections probably begin in one of the contiguous end plates, and the disc is infected secondarily. In children, there is some controversy as to the origin. Most cultures and biopsies in children are negative, leading experts to believe that childhood discitis may not be an infectious condition, but caused by partial dislocation of the epiphysis (the growth area near the end of a bone), as a result of a flexion injury.

Symptoms vary depending on the type of spinal infection but, generally, pain is localized initially at the site of the infection. In postoperative patients, these additional symptoms may be present:

  • Wound drainage
  • Redness, swelling or tenderness near the incision
  • Severe back pain
  • Fever
  • Chills
  • Weight loss
  • Muscle spasms
  • Painful or difficult urination
  • Neurological deficits: weakness and/or numbness of arms or legs, incontinence of bowels and/or bladder

Patients may initially have few symptoms, but eventually develop severe back pain. Generally, younger, preverbal children do not have a fever nor seem to be in pain, but they will refuse to flex their spines. Children age three to nine typically present with back pain as the predominant symptom

Postoperative disc space infection may be present after surgery, occurring, on average, one month after surgery. The pain is usually alleviated by bed rest and immobilization, but increases with movement. If left untreated, the pain gets progressively worse and intractable, unresponsive even to prescription painkillers.

Adult patients often progress through the following clinical stages:

  1. Severe back pain with fever and local tenderness in the spinal column
  2. Nerve root pain radiating from the infected area
  3. Weakness of voluntary muscles and bowel/bladder dysfunction
  4. Paralysis

In children, the most overt symptoms are prolonged crying, obvious pain when the area is palpated and hip tenderness.

In general, symptoms are usually nonspecific. If a paraspinal abscess is present, the patient may experience flank pain, abdominal pain or a limp. If a psoas muscle abscess is present, the patient may feel pain radiating to the hip or thigh area.