Ankylosing spondylitis

Background

• Ankylosing spondylitis (AS) is a chronic inflammatory disease of the axial skeleton with variable involvement of other joints or even nonarticular structures
• 3x more common in males than females
• Typically diagnosed in young adults between the ages of 20 and 30 yrs
• Often associated with other autoimmune disorders
• 90% of people with AS express the HLA-B27 genotype
• Uveitis is common extra-articular manifestation, seen in 30% of patients

Clinical Features

• Spinal pain, particularly in the lower back, is usually the first and most common symptom of AS
  • Begins in early adulthood (before 45 yrs)
  • Has a gradual onset
  • Lasts longer than three months
  • Is worse after rest (for example, in the morning) but improves with activity
  • Can cause morning stiffness lasting more than 30 minutes
• Fatigue
• Can also be associated with anterior uveitis, arthritis, bowel ulcers and spine fractures (4 times more common in patients with AS )

Differential Diagnosis

Lower Back Pain

• Spine related
  • Acute ligamentous injury
  • Acute muscle strain
  • Disk herniation (Sciatica)
  • Degenerative joint disease
  • Spondylolithesis
  • Epidural compression syndromes
    • Spinal cord compression (non-traumatic)
    • Cauda equina syndrome
    • Conus medullaris syndrome
    • Epidural abscess (spinal)
    • Epidural hematoma (spinal)
  • Thoracic and lumbar fractures and dislocations
  • Cancer metastasis
  • Spinal stenosis
  • Transverse myelitis
  • Vertebral osteomyelitis
  • Ankylosing spondylitis
  • Spondylolisthesis
  • Discitis
  • Spinal Infarct
• Renal disease
  • Kidney stone
  • Pyelonephritis
  • Nephrolithiasis
• Intra-abdominal
  • Abdominal aortic aneurysm
  • Ulcer perforation
  • Retrocecal appendicitis
  • Large bowel obstruction
  • Pancreatitis
• Pelvic disease
  • PID
• Other
  • Retroperitoneal hemorrhage/mass
  • Meningitis

Evaluation

• There is no direct test for AS
• ESR, CRP can be elevated but not sensitive or specific
• Xray lumbar/sacroiliac: The earliest changes in the sacroiliac joints shows erosions and sclerosis
  • Progression of erosions leads to pseudo widening of the joint space and bony ankylosis AKA "Bamboo Spine"

Often X-ray findings lag about 10 years from initial progression of disease

"bamboo spine"

• CBC
• Chem 10
• Urinalysis
• Genetic testing for HLA B27 ( > 90% of people with AS have this gene, though by itself is not specific)

Management

• There is no cure for AS, although treatments (e.g. exercise, posture training) and medications can reduce symptoms and pain
• NSAIDS
• Sulfasalazine can be used in people with peripheral arthritis, but for axial involvement, evidence does not support it .
• Lack of evidence for methotrexate or steroids.
• Tumor necrosis factor-alpha blockers, such as the biologics etanercept, infliximab, golimumab and adalimumab, provide good short-term effectiveness though long term management is currently being studied

Disposition

• Often diagnosis will not be made in ED but if made in ED often can be discharged home with primary care follow up or rheumatology follow up

See Also

• Arthritis