Ankylosing spondylitis

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128 Ankylosing spondylitis

Instruction

Examine this patient’s back.

Examine this patient.

Salient features

History

• Back stiffness and back pain: worse in the morning, improves on exercise and worsens on rest

• Symptoms in the peripheral joints (in ~40%), particularly shoulders and knees

• Onset of symptoms is typically insidious and in the 3rd–4th decade

• Extra-articular manifestations: red eye (uveitis), diarrhoea (GI involvement), history of aortic regurgitation, pulmonary apical fibrosis (worse in smokers).

Examination

• ‘Question mark’ posture (as a result of loss of lumbar lordosis, fixed kyphoscoliosis of the thoracic spine with compensatory extension of the cervical spine)

• Protuberant abdomen.

Proceed as follows:

• Ask the patient to look to either side: the whole body turns when the patient does this.

• Examine the cervical, thoracic and lumbar spines (remember that cervical spine involvement occurs later in the disease and results in pain and a grating sensation on movement of the neck).

• Measure the occiput-to-wall distance (inability to make contact when heel and back are against the wall indicates upper thoracic and cervical limitation).

• Perform Schober’s test. This involves marking points 10 cm above and 5 cm below a line joining the ‘dimple of Venus’ on the sacral promontory. An increase in the separation of <5 cm during full forward flexion indicates limited spinal mobility.

Note: Finger–floor distance is a simple indicator but is less reliable because good hip movement may compensate for back limitation.

• Examine for distal arthritis (occurs in up to 30% of patients and may precede the onset of the back symptoms). Small joints of the hand and feet are rarely affected.

• Measure chest expansion with a tape (<5 cm suggests costovertebral involvement).

• Tell the examiner that you would like to examine the following:

• Eyes for iritis, anterior uveitis (seen in 20% of patients)

• Heart for aortic regurgitation (seen in 4% of patients who have had the disease for over 15 years), cardiac conduction defects

• Lungs for mild restrictive disease, apical fibrosis, apical cavities and secondary fungal infection; look for cyanosis (patients with rigid spine syndrome often have underlying hypoventilation)

• CNS, such as tetraplegia, etc.

• Foot for Achilles tendinitis and plantar fasciitis.

• The four ‘A’s of ankylosing spondylitis: apical fibrosis, anterior uveitis, aortic regurgitation, Achilles tendinitis

• That psoriasis and Reiter syndrome can also cause sacroiliitis.

Diagnosis

This patient has fixed kyphoscoliosis of the thoracic spine with loss of lumbar lordosis (lesion) caused by ankylosing spondylitis (aetiology) on Schober’s test; spinal movements are severely diminished (functional status).

Questions

What are the diagnostic criteria for ankylosing spondylitis?

Modified New York criteria 1984 for ankylosing spondylitis definite ankylosing spondylitis is present if the radiological criterion is associated with at least one clinical criterion:

Clinical criteria:

• Low-back pain and stiff ness for longer than 3 months, which improve with exercise but are not relieved by rest

• Restriction of motion of the lumbar spine in both the sagittal and frontal planes

• Restriction of chest expansion relative to normal values correlated for age and sex.

Radiological criterion:

• Sacroiliitis grade ≥2 bilaterally, or grade 3–4 unilaterally

What investigations would you like to do in this patient?

Anteroposterior view of sacroiliac joints and lateral radiographs of lumbar spine (Fig. 128.1A): the earliest changes are erosions and sclerosis of the sacroiliac joints. Later in the disease syndesmophytes may be found in the lumbosacral spine. In severe disease, involvement progresses up the spine, leading to a ‘bamboo spine’ (Fig. 128.1B). Although the New York criteria require a combination of clinical and radiographic features, the diagnosis should be suspected on the basis of inactivity, spinal stiffness and pain, with or without additional features.

Fig. 128.1 Ankylosing spondylitis. (A) Bone erosion of dorsal aspect of thoracic spine. (B) Bamboo spine.

(With permission from Kelley WN Harris ED, Ruddy S, et al. (eds) Textbook of rheumatology, 5th edn, vol. 1. Philadelphia, PA: Saunders, 1997.)

In which other seronegative arthritic disorders is low-back pain a feature?

Sacroiliitis is often seen in Reiter syndrome, psoriatic arthritis, juvenile chronic arthritis and intestinal arthropathy.

How would you manage a patient with ankylosing spondylitis?

• Encourage exercise, particularly physical therapy, to preserve back extension

• NSAIDs, in particular indomethacin. Phenylbutazone is reserved for resistant cases

• Methotrexate and sulfasalazine

• Tumour necrosis factor blockers: etanercept, adalimumab, and golimumab. Etanercept decreases stiffness and pain and improvesoverall function, plus showing objective findings such as an increase in chest expansion and a decrease in the ESR (N Engl J Med 2002;346:1349)

• Surgical therapy, consisting of vertebral wedge osteotomy, is occasionally indicated

• Referral to ophthalmologist when anterior uveitis occurs.

Advanced-level questions

What genetic counselling would you give this patient?

In HLA-B27-positive patients, the siblings have a 30% chance of developing this disease. Hence children of such patients who develop symptoms such as joint pains or sore eyes should be referred to a rheumatologist.

What is the natural history of the disease?

About 40% go on to develop severe spinal restriction; about 20% have significant disability. Early peripheral joint disease, particularly of the hip, indicates a poor prognosis.

What is the risk in those with a ‘bamboo’ cervical spine when driving?

Increased susceptiblity to whiplash injury and restricted lateral vision.

What therapy may the patient have received in the past if the blood film shows a leukaemic picture?

In the past, patients were treated with irradiation of the spine. However, those treated tend to develop leukaemia several years after therapy.

What criteria predict that lower-back pain is a precursor of ankylosing spondylitis?

New criteria for inflammatory back pain in young to middle-aged adults (<50 years) with chronic back pain are:

• Morning stiffness >30 min

• Improvement in back pain with exercise but not with rest

• Awakening because of back pain during the second half of the night only

• Alternating buttock pain

• Diagnosis is confirmed if at least two of the four the parameters are present (sensitivity 70.3%, specificity 81.2%).

Further reading

Keat A. Spondyloparthropathies. BMJ. 1995;310:1321-1324. classic review

The term ankylosing spondylitis derives from the Greek words, ankylos (bent or crooked) and spondylos (vertebra). Past names have included Marie–Strümpell disease and von Bechterew’s disease.

The first clinical report of ankylosing spondylitis (1831) concerned a man from the Isle of Man. Vladimir von Bechterew of St Petersburg, Russia, described a series of cases between 1857 and 1927. Adolf Strümpell (1853–1926) of Erlangen and Pierre Marie (1853–1940) of Paris independently described this condition in 1897 and 1898, respectively.

HC Reiter (1881–1969), a German physician.

Achilles is a figure from Greek mythology who was a hero of the Trojan war. His mother dipped him into the river Styx, holding him by his heel, to make him invulnerable to the attack. He slew Hector in this war, but was himself slain, wounded in his vulnerable heel by Paris.

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