- Discitis is an infection of the disc space and vertebral endplate that is caused by hematogenous or postoperative inoculation.
- It affects intervertebral discs of the spine.
- The lower lumbar discs are most commonly involved.
- However, the infection may occur in any disc.
- Spontaneous (hematogenous)
- Iatrogenic (after discectomy or discogram)
- Hematogenous infection is uncommon.
The mean age of occurrence of hematogenous (spontaneous) discitis is 7 years, but it may affect individuals of any age.
The incidence of infection after discectomy is <1%.
- Compromised host (patients with diabetes, alcohol abuse, transplants)
- Intravenous drug abuse
- Procedures involving the disc (discography, discectomy, spinal anesthesia)
- Bacterial infection:
- The causative organism most commonly is Staphylococcus, except in the compromised host or intravenous drug abuser, in whom Gram-negative aerobic bacteria and Candida are more common (for these patients, biopsy is indicated).
- Vascularity issues in children <8 years old:
- The blood supply to the disc comes from the adjacent vertebral body.
- Vessels cross the cartilaginous endplate in children until they are approximately 8 years old, and the resultant vascularity renders younger children susceptible to infection in the area.
Signs and Symptoms
- Back pain, usually insidious in onset but increasing with time
- Abdominal pain
- Loss of appetite
- Back stiffness
- Refusal to walk
- Pain on spinal percussion
- Loss of lordosis
- Fever: Usually low-grade, but may be absent
- Note the presence or absence of normal lumbar lordosis.
- Look for pain or refusal to bend forward.
- Look for pain on paraspinal percussion.
- Look for pain on abdominal palpation in lumbar discitis.
- Neurologic examination remains normal, except in late presentations of fulminant discitis.
- White blood cell count, ESR, and C-reactive protein usually are mildly elevated but may be normal.
- Obtain a blood culture even though it is positive <30% of the time.
- No specific laboratory tests exists for this disorder.
- Plain films are positive only after several weeks; they show irregularity and narrowing of the disc space, with mild osseous involvement.
- For suspected cases of discitis, shows the pathologic features before abnormalities are visible radiographically.
- Gives more detailed anatomic information than a bone scan, but a bone scan is an acceptable alternative
- Pathological Findings
- Chronic inflammation
- Destruction of disc structure and endplates
- Differential Diagnosis
- Tuberculosis (usually shows more destruction of adjacent bone)
- Vertebral osteomyelitis (more destruction of bone than disc, but these 2 entities may merge)
- General Measures
- For childhood spontaneous discitis, no biopsy or debridement is needed because treatment of staphylococcal infection is virtually always successful.
- This treatment should be given intravenously if the patient is severely ill, orally if the patient is only mildly symptomatic.
- Bed rest and bracing may be used if pain is pronounced.
- For discitis in the compromised host, biopsy and drainage should be performed.
- Special Therapy
- Physical Therapy
- Therapy is useful for adults with severe back stiffness after treatment has begun.
- Medication (Drugs)
- For routine spontaneous discitis, oxacillin, dicloxacillin, and cephalosporin are indicated.
- For complicated cases or in compromised hosts, broad-spectrum antibiotics effective against Gram-negative and anaerobic organisms should be added.
- NSAIDs or mild narcotics may help patients with severe pain initially until the infection is controlled.
- Biopsy may be required in the immunocompromised patient, or one for whom medical therapy has failed.
- Anterolateral or posterolateral approach with fluoroscopic guidance
- Drainage may be required for patients who fail to respond to medical management alone.
- Usually obtained via an anterior approach to allow adequate visualization, debridement, and safety
- Surgical reconstruction of the spine segment may be indicated for adults with substantial disc space destruction or endplate compromise.
- Prognosis is good once the infection has cleared.
- After childhood discitis, the vertebrae adjacent to the infected disc usually develop a spontaneous painless fusion.
- In adults, spontaneous fusion does not always occur, and back pain may persist.
- Persistence of infection (lack of symptom improvement in 1-2 weeks) requires accurate identification of the organism and adequate debridement.
- Patient Monitoring
- Physical examination is the most useful means for monitoring infection healing.
- The examiner should check for tenderness to percussion and range of forward flexion.
- Radiographs and ESR lag far behind the clinical course.