Basics
Description
- Chronic inflammatory disease, primarily affects the axial skeleton with predilection toward the spine and sacroiliac (SI) joints:
- SI joints 100%
- Cervical spine 75%
- Thoracic spine 70%
- LS spine 50%
- Hip joints 30%
- Shoulder joints 30%
- Spondylitis (inflammation of vertebrae) of ankylosing spondylitis (AS) begins at the insertions of the outer fibers of the annulus fibrosus (enthesitis) of the vertebrae:
- Ossification (syndesmophyte formation) may lead to complete fusion, ankylosis, of the vertebrae.
- Extensive spinal involvement causes the radiographic appearance of the brittle "bamboo spine."�
- Onset 15-35 yr of age
- Male to female ratio is between 2:1 and 3:1.
AS patients are at 4 times the risk for fracture and paralysis compared to the general population. They are 11 times more likely to have spinal cord injuries. �
Risk Factors
Genetics
Strong genetic component. HLA-B27 is present in 80-90% of patients with AS. �
Etiology
Disease is likely triggered by environmental factors such as infection in genetically predisposed individuals. �
Diagnosis
Signs and Symptoms
- Spinal: Low back pain with sacroiliitis is the most common presentation:
- Inflammatory back pain, improving with movement and exercise.
- Higher risk for serious injury from milder traumatic mechanisms.
- Extraspinal inflammatory conditions (which may precede spinal symptoms):
- Ocular (the most common):
- Uveitis (25-40% occurrence). Usually acute and unilateral in onset. Can alternate eyes.
- Cardiac:
- Slight increased risk of CAD
- Increased risk for valvular incompetence with prolonged course of AS.
- Pulmonary:
- Progressive restrictive lung disease due to limited expansion and fibrosis
- GI:
- 5-10% of patients with inflammatory bowel disease.
- GU:
- Risk for IgA nephropathy or amyloidosis. Also increased risk for NSAID nephropathy from anti-inflammatory use.
- Enthesitis (inflammation at tendon or ligament insertion):
- Often Achilles tendonitis or plantar fasciitis
History
- Patients <40 yr of age with insidious onset of low back pain >3 mo, radiating into gluteal areas from SI region, and progressing to involve the entire spinal region:
- Worse with rest and improved with mild activity. Pain in 2nd half of night waking patient from sleep
- Women may have more cervical and extraspinal manifestations than men.
- Possible prior history of uveitis, restrictive pulmonary disease, inflammatory bowel disease, enthesitis, or migrating or polyarthritis.
Physical Exam
- Tenderness over SI joints elicited with direct pressure over both of patients ASIS simultaneously.
- Dactylitis or enthesitis.
- Flattening of the normal lumbar lordosis
- Exaggeration of thoracic kyphosis
- Limitation of spinal movement
- Reduction in chest expansion
- Patients with juvenile ankylosing spondylitis (JAS) may commonly be misdiagnosed as recurrent sprains
- Onset of JAS is late childhood or adolescence (between 8 and 12 yr, before age 20); primarily boys.
- JAS has a much greater predilection for extraspinal joints and entheses of the lower extremities; in addition to SI tenderness, examine for:
- Asymmetrical pauciarthritis of the joints of the lower extremities
- Enthesitis of the ankle, knee, or tarsal bones. Plantar fasciitis and Achilles tendonitis are often common findings.
Essential Workup
- Exclude fracture and neurologic injury in any patient with suspected AS for any new spinal pain (even without trauma).
- Exclude sepsis or septic joint if clinically indicated.
- Evaluate for sacroiliitis with pelvic rock test (compression) or Patrick test (downward pressure on the knee of a flexed and externally rotated leg and the contralateral ASIS causing sacral distraction).
Diagnosis Tests & Interpretation
Lab
- CBC may show mild leukocytosis with slight to moderate anemia and thrombocytosis.
- BUN, creatinine, and electrolytes may be useful to assess renal involvement.
- Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) may be elevated, but are of limited use in the ED.
- HLA-B27 testing can be performed by a specialist. A negative result does not rule out AS.
Imaging
- Pelvic radiograph: Should be done in any adult patient suspected of undiagnosed ankylosing spondylitis:
- Sacroiliitis is essential to the diagnosis of AS; this is seen initially as subchondral bony erosions on the iliac side of the SI joint, which later manifest as bony proliferation and sclerosis.
- If plain films are negative for sacroilitis, MRI should be considered.
- Lumbar, thoracic, and cervical spine radiographs to exclude fracture for complaint of new pain to these areas with or without trauma
- CT should be performed to further evaluate possible fractures on plain radiographs.
- MRI should be performed emergently on any patient with neurologic deficit.
- Chest radiograph may show patchy inflammatory infiltrates or apical fibrosis.
Diagnostic Procedures/Surgery
- Electrocardiogram indications:
- Symptoms of acute coronary syndrome (slightly increased risk compared to general population for CAD)
- Symptomatic arrhythmia:
- Echocardiogram indications:
- New murmur: Increased predilection for aortic insufficiency with AS
- Evidence of new heart failure.
Differential Diagnosis
- JAS:
- Onset before age 20
- More enthesitis and extraspinal joint involvement.
- Reactive arthritis (formerly Reiter syndrome):
- Arthritis, urethritis, and conjunctivitis beginning about 1 mo after an episode of urethritis or enteritis.
- Enteropathic arthritis:
- Crohns disease or ulcerative colitis
- Primarily involves knee, elbow, ankle, or wrist, and usually exacerbated by flares of the bowel disease
- Psoriatic arthritis:
- Psoriasis rash
- Much greater predilection for the hands and feet with higher incidence of dactylitis.
- Septic arthritis:
- Exclude with arthrocentesis if clinically suspected in single joint involvement.
- Mechanical low back pain:
- Improved with rest and exacerbated by exercise without signs of systemic inflammatory process.
- Spinal epidural abscess:
- More constant, unremitting, and typically associated with fever and history of IVDA or immunosuppression.
- Neoplastic low back pain:
- Typically in patients older than 40, more constant and unremitting, and more characteristically at night.
Treatment
Pre-Hospital
- High risk of spinal injury from minor trauma.
- Spinal immobilization must avoid creating further injury:
- Cushion stabilization and scoop board in position of comfort may be a better approach than cervical collar and/or backboard.
- Intubation difficulty
- Cervical and TMJ restriction may limit success in all but fiberoptic techniques.
- Consider alternative airway approaches such as LMA or bag valve mask with oral airway until definitive airway can be achieved safely (usually fiberoptic).
- Ventilation difficulty
- Chest wall restriction from deformity and pulmonary fibrosis
- CPR may carry a higher likelihood of rib fractures
Ed Treatment/Procedures
- Exclude cord compression if clinically suspected (MRI is the study of choice).
- Exclude spinal fracture for any new spinal pain (CT may be necessary).
- Exclude infection if clinically suspected with laboratory analysis and arthrocentesis.
- Control pain and inflammation with NSAIDs
Medication
- Nonselective NSAIDs:
- Ibuprofen: 35 mg/kg/d divided QID, max. 50 mg/kg/d (adult: 300-800 mg PO TID or QID)
- Indomethacin: 1-2 mg/kg/d divided BID or QID, max. 4 mg/kg/d (adult: 25 mg PO BID or TID)
- Not well tolerated, especially at higher doses because of GI and CNS effects
- Naproxen: 10 mg/kg/d divided BID, max. 1,000 mg/d (adult: 250-500 mg PO BID)
- COX 2 inhibitors:
- Celecoxib (adult: 100 mg-200 mg PO BID)
- TNF-α inhibitors:
- Adalimumab (adult: 40mg SubQ q2wk)
- Etanercept (adult: 50mg SubQ qwk)
- NSAIDs should be avoided in pregnancy.
- Acetaminophen is 1st line
- Opioids are 2nd line
NSAID use may increase risk in the elderly for cardiovascular disease, GI bleeding, renal function, and hypertension. Although effective in select patients, close follow-up is prudent. �
- NSAIDs:
- GI bleeding risks
- Elderly, history of PUD, concurrent use of glucocorticoids, anticoagulants, aspirin, smoking, alcohol.
- Consider celecoxib or adding an H2 blocker or PPI if patient is at higher risk for GI bleeding.
Second Line
Consider if NSAIDs or acetaminophen are ineffective at appropriate doses: �
- Opioid analgesics, muscle relaxants, or low-dose steroids.
Follow-Up
Disposition
Admission Criteria
- Acute neurologic impairment
- Intractable pain
- Sepsis or septic joint cannot be excluded.
Discharge Criteria
- No serious injuries or neurologic deficit
- Pain is manageable to the patient
Issues for Referral
- The patient should be encouraged to obtain a medical alert bracelet.
- Rheumatology:
- Patients with evidence of a new diagnosis of AS should be considered for early referral to a specialist in rheumatology for immunomodulative therapy.
- Physical medicine and rehabilitation:
- Resting splints for inflamed joints
- Orthoses for enthesitis (such as heel cushion inserts to rest Achilles tendon attachment)
Follow-Up Recommendations
- Routine primary care re-evaluation within 1-2 wk to assess response to treatment.
- Referral to a rheumatologist for immunomodulating medications.
- Earlier follow-up in any patient with higher risk for adverse response to NSAIDs:
- Elderly, hypertensive patients, and patients with higher GI bleeding risks.
Pearls and Pitfalls
- Intubation is likely to be difficult and should avoid neck repositioning due to risk of C1 subluxation.
- Consider airway adjuncts (such as LMA) until a definitive airway (usually fiberoptic) can be safely assured.
- Immobilization must avoid creating additional injury
- Consider cushion/tape stabilization in position of comfort rather than standard cervical collar and backboard
- Minor traumatic injuries in AS can result in spinal fracture and possible cord injury. Maintain a high clinical suspicion.
Additional Reading
- Baraliakos �X, van den Berg �R, Braun �J, et al. Update of the literature review on treatment with biologics as a basis for the first update of the ASAS/EULAR management recommendations of ankylosing spondylitis. Rheumatology. 2012;51(8):1378-1387.
- Chakravarty �SD, Paget �SA. Ankylosing spondylitis: Pathogenesis, diagnosis, and therapy. Rheumatology. 2012;40:39-43.
- Sieper �J, Braun �J. Ankylosing Spondylitis: In Clinical Practice. Britain: Springer, 2010.
See Also (Topic, Algorithm, Electronic Media Element)
http://www.spondylitis.org �
Codes
ICD9
720.0 Ankylosing spondylitis �
ICD10
- M45.2 Ankylosing spondylitis of cervical region
- M45.8 Ankylosing spondylitis sacral and sacrococcygeal region
- M45.9 Ankylosing spondylitis of unspecified sites in spine
- M45.4 Ankylosing spondylitis of thoracic region
- M45.0 Ankylosing spondylitis of multiple sites in spine
- M45.1 Ankylosing spondylitis of occipito-atlanto-axial region
- M45.3 Ankylosing spondylitis of cervicothoracic region
- M45.5 Ankylosing spondylitis of thoracolumbar region
- M45.6 Ankylosing spondylitis lumbar region
- M45.7 Ankylosing spondylitis of lumbosacral region
- M45 Ankylosing spondylitis
SNOMED
- 9631008 Ankylosing spondylitis (disorder)