What are the clinical signs of discitis?

Clinical Signs of Discitis

The most important clinical signs of discitis include back pain, fever, restricted spinal movement, and elevated inflammatory markers, which should prompt immediate diagnostic evaluation to prevent serious complications such as spinal cord compression and neurological deficits. 1

Cardinal Clinical Manifestations

• Back or neck pain: Persistent, localized pain at the affected spinal level is the most common presenting symptom, occurring in over 90% of patients 2
• Fever: Low-grade fever (>37.5°C) is present in approximately 68% of cases, though it may not always be evident 2
• Restricted spinal movement: Paravertebral muscle spasm and limited range of motion due to pain 1, 3
• Tenderness: Localized spinous process tenderness on palpation 4

Neurological Signs

• Radiculopathy: Radiating pain in a dermatomal distribution suggesting nerve root irritation 4
• Motor deficits: Weakness in muscle groups corresponding to affected nerve roots 1
• Sensory changes: Altered sensation in specific dermatomes 1
• Myelopathy: In severe cases with spinal cord compression, signs of upper motor neuron dysfunction may develop 1

Laboratory Findings

• Elevated erythrocyte sedimentation rate (ESR): Present in approximately 91% of patients and serves as the most useful laboratory marker for both diagnosis and monitoring disease activity 2, 4
• Elevated C-reactive protein (CRP): Another important inflammatory marker that rises in discitis 1
• Leukocytosis: White blood cell count may be elevated, though not consistently 1

Risk Factors to Identify

• Age: Higher incidence in patients over 65 years (73% of cases) 2
• Recent invasive procedures: Spinal surgery, injections, or other invasive procedures (41% of cases) 2
• Immunocompromise: Conditions such as diabetes mellitus (18% of cases), cancer (25% of cases), HIV, or dialysis 1, 2
• Intravenous drug use: Important risk factor to identify 1
• Pre-existing degenerative spinal disease: Present in 50% of patients 2

Pediatric-Specific Signs

• Irritability: Common in children with discitis 1
• Limping: May be present, especially in children between 2-12 years 1
• Decreased range of motion: Children may refuse to bend or move their spine 1
• Nighttime pain: Persistent pain that wakes the child at night 1

Diagnostic Pitfalls and Caveats

• Delayed diagnosis: The average delay from presentation to diagnosis can be 14 weeks, highlighting the need for high clinical suspicion 4
• Absence of fever: Not all patients present with fever, especially elderly patients 3
• Negative blood cultures: Blood cultures may be negative despite active infection; disc space aspiration may be necessary for microbiological diagnosis 5, 2
• Normal radiographs: Plain radiographs have low sensitivity in early stages of disease 1
• Multifocal involvement: Discitis can affect multiple levels, particularly in IV drug users or with certain pathogens like tuberculosis 1

Red Flag Combinations

• The triad of back pain + restricted spinal movements + elevated inflammatory markers should immediately raise suspicion for discitis 3
• Persistent nighttime pain unresponsive to conservative management, especially in patients with risk factors 1
• Progressive neurological deficits with back pain warrant urgent evaluation to rule out epidural abscess or spinal cord compression 1

Complications to Monitor

• Epidural abscess: Can cause spinal cord compression requiring urgent surgical intervention 1
• Paravertebral abscess: Collection of purulent material in the paravertebral space 1
• Spinal instability: Due to bony destruction of vertebral bodies 1
• Paraplegia: A serious but preventable complication if diagnosed and treated early 3

MRI is the imaging modality of choice for suspected discitis due to its high sensitivity and specificity, especially in early stages of the disease when radiographs may be normal 1, 5.