Discitis
Introduction
Discitis, also known as diskitis, is an inflammatory disorder affecting the intervertebral disc space. This condition is relatively rare but can cause significant morbidity. Discitis can occur at any age but is more frequently observed in children and older adults. The inflammation can be caused by infection, autoimmune responses, or post-surgical complications. Understanding the etiology, clinical presentation, diagnostic methods, and treatment options is crucial for effective management.
Etiology
Discitis can be classified based on its etiology into infectious and non-infectious types.
Infectious Discitis
Infectious discitis is often caused by bacterial pathogens, with Staphylococcus aureus being the most common. Other bacteria such as Escherichia coli, Pseudomonas aeruginosa, and Mycobacterium tuberculosis can also be responsible. The infection can reach the disc space through hematogenous spread, direct inoculation during surgery, or contiguous spread from adjacent infected structures.
Non-Infectious Discitis
Non-infectious discitis may result from autoimmune conditions such as ankylosing spondylitis or rheumatoid arthritis. It can also occur as a reaction to spinal surgery or other mechanical insults to the spine.
Pathophysiology
The intervertebral disc is an avascular structure, which makes it susceptible to infection and inflammation. In infectious discitis, bacteria can lodge in the disc space, leading to an inflammatory response. This response involves the recruitment of immune cells, release of cytokines, and subsequent degradation of the disc material. In non-infectious discitis, the inflammation is driven by autoimmune mechanisms or physical trauma, leading to similar degradation and inflammation.
Clinical Presentation
Patients with discitis typically present with severe back pain, which is often localized to the affected disc level. The pain may radiate to the extremities and is usually exacerbated by movement. Other symptoms can include fever, malaise, and neurological deficits if there is spinal cord or nerve root involvement. In children, the presentation may be more subtle, with symptoms such as irritability, refusal to walk, or abdominal pain.
Diagnosis
The diagnosis of discitis involves a combination of clinical evaluation, laboratory tests, and imaging studies.
Clinical Evaluation
A thorough history and physical examination are essential. The clinician should inquire about recent infections, surgeries, or other risk factors. Physical examination may reveal localized tenderness, reduced range of motion, and signs of neurological impairment.
Laboratory Tests
Laboratory tests can provide supportive evidence for the diagnosis. Elevated C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are common findings. Blood cultures may be positive in cases of infectious discitis.
Imaging Studies
Magnetic resonance imaging (MRI) is the gold standard for diagnosing discitis. MRI can reveal disc space narrowing, endplate irregularities, and inflammatory changes in the adjacent vertebrae. Computed tomography (CT) and X-ray can also be used but are less sensitive. In some cases, a biopsy of the disc space may be required to identify the causative organism.
Treatment
The treatment of discitis depends on the underlying cause and severity of the condition.
Medical Management
Infectious discitis is primarily treated with antibiotics. The choice of antibiotic should be guided by the results of blood cultures and sensitivity testing. Empirical therapy often includes broad-spectrum antibiotics such as vancomycin and ceftriaxone. The duration of antibiotic therapy can range from 6 weeks to several months.
Non-infectious discitis may be managed with anti-inflammatory medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids. Physical therapy and pain management strategies are also important components of treatment.
Surgical Management
Surgery may be indicated in cases of severe discitis with neurological deficits, spinal instability, or failure of medical management. Surgical options include debridement of the infected disc, spinal fusion, and stabilization procedures.
Prognosis
The prognosis of discitis varies depending on the cause and promptness of treatment. Infectious discitis generally has a good prognosis if treated early with appropriate antibiotics. Delayed treatment can lead to complications such as osteomyelitis, spinal abscess, and chronic pain. Non-infectious discitis also has a favorable prognosis with appropriate medical management, although some patients may experience persistent pain and functional limitations.
Complications
Complications of discitis can be severe and include:
- **Spinal Abscess**: Formation of an abscess can compress the spinal cord or nerve roots, leading to neurological deficits.
- **Osteomyelitis**: Spread of infection to the adjacent vertebrae can cause osteomyelitis, further complicating treatment.
- **Chronic Pain**: Persistent inflammation and structural damage can result in chronic back pain.
- **Spinal Instability**: Destruction of the disc and adjacent vertebrae can lead to spinal instability, necessitating surgical intervention.
Prevention
Preventive measures for discitis include:
- **Aseptic Techniques**: Ensuring aseptic techniques during spinal surgeries and procedures to prevent direct inoculation of pathogens.
- **Prompt Treatment of Infections**: Early and appropriate treatment of systemic infections to prevent hematogenous spread to the spine.
- **Immunization**: Vaccination against common pathogens such as Streptococcus pneumoniae and Haemophilus influenzae in at-risk populations.